WO2014009578A1 - Method for obtaining an individual's genetic profile by means of x chromosome loci analysis - Google Patents

Method for obtaining an individual's genetic profile by means of x chromosome loci analysis Download PDF

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WO2014009578A1
WO2014009578A1 PCT/ES2013/000170 ES2013000170W WO2014009578A1 WO 2014009578 A1 WO2014009578 A1 WO 2014009578A1 ES 2013000170 W ES2013000170 W ES 2013000170W WO 2014009578 A1 WO2014009578 A1 WO 2014009578A1
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seq
locus
dxs
loci
dna
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PCT/ES2013/000170
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Spanish (es)
French (fr)
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Maria CASTAÑEDA FERNÁNDEZ
Adrián ODROZIOLA MARTÍNEZ
Maria Teresa ZARRABEITIA CIMIANO
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Universidad De Cantabria
Fundación Marqués De Valdecilla
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Publication of WO2014009578A1 publication Critical patent/WO2014009578A1/en

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    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12QMEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/68Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
    • C12Q1/6844Nucleic acid amplification reactions
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12QMEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/68Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
    • C12Q1/6844Nucleic acid amplification reactions
    • C12Q1/686Polymerase chain reaction [PCR]
    • CCHEMISTRY; METALLURGY
    • C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12QMEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
    • C12Q1/00Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
    • C12Q1/68Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
    • C12Q1/6876Nucleic acid products used in the analysis of nucleic acids, e.g. primers or probes

Definitions

  • the invention relates to a method for obtaining the genetic profile of an individual comprising the analysis of 4 or more STRs loci, up to a total of 8 loci, all located on the X chromosome, in a DNA extract of said individual by a multiplex amplification reaction.
  • the present invention is also directed to a kit comprising the pairs of primers for the implementation of the method of the invention. Both the method and the kit described here are applicable in the identification of individuals in the area of forensic genetics, as well as in population genetics, anthropology and biomedicine.
  • the X chromosome comprises 155 Mb and represents 5% of the total genetic material of the cells. It contains approximately 1 100 genes. Only 1.7% of this chromosome encodes functional proteins, presenting a high content of repetitive non-coding DNA (Ross et al., 2005 Nature 434: 325-337). Part of this fraction are short regions repeated in tandem or "short tandem repeats" (STR). To date, more than fifty STRs have been described on the X chromosome whose analysis is fundamentally of interest among others, in Forensic Genetics and in the aforementioned disciplines (Gusmao et al., 2012 Methods Mol. Biol. 830: 57-71 ). The analysis of microsatellite markers called STRs (Short Tandem Repeats) is nowadays the reference technique for obtaining genetic profiles aimed at identifying individuals, determining kinship or crime.
  • STRs Short Tandem Repeats
  • X-chromosome STR analysis is a complementary tool of high interest (Zarrabeitia et al., 2002 Forensic Sci. Int. 129 (2): 85-89; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74; Liu et al, 2008 Int. J. Legal Med. 122: 261-265). Likewise, it has demonstrated great utility in the identification of individuals.
  • the haplotype of the paternal X and Y chromosome can be detected respectively in the female and male offspring.
  • This X chromosome that the mother transmits may be an exact copy of any of its chromosomes or it may have undergone recombination between the two X chromosomes and be different from the initial copy that the woman possesses (Wakefield et al., 2006 Encyclopedia of life sciences ).
  • the haplotype of the father's X chromosome will be identical to one of the paternal grandmother's chromosomes, so if at least one allele of each marker analyzed by the grandmother does not match that of the granddaughter, biological paternity can be ruled out. These analyzes have a high probability of exclusion. In turn, in those cases in which the grandmother is also unavailable, her genotype can be reconstructed through the study of the siblings of the alleged father (Szibor et al, 2007 Forensic Sci.
  • the microsatellites of the X chromosome complement the autosomal STR analysis, since if the daughter becomes pregnant, in her female offspring there will be no allele other than those present in said parent. Its usefulness would stand out in terms of excluding a supposed incest. While due to the limitations of inclusion of the X chromosome STRs, it is necessary to consider that the X chromosome haplotype can be shared by other members of the same family (Szibor et al., 2007 Forensic Sci. Int: Genet. 1: 93-97; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74).
  • X-chromosome microsatellite studies are especially useful in identifying a female profile in evidence that contains a mixture of male and female DNA.
  • the alleles of the female sample can be completely masked by the alleles of the male sample, only if the woman is homozygous and coincides in all loci with the man, very unlikely event. Therefore, these analyzes are useful in solving criminal cases in which we give as an example, it is necessary to demonstrate the presence of female epithelial or vaginal cells, in the body of the alleged aggressor or in objects with which there are been in touch
  • the degradation of DNA is characterized by a general fragmentation of the genetic material, where DNA fragments can be around 240 bp, and these reactions require larger fragments (table 2), for the analysis of all STRs loci that include commercial kits.
  • Highly degraded DNA is a characteristic of most of the samples that are analyzed in criminal genetic laboratories, in kinship diagnoses and also of those obtained from biological samples contained in paraffin in health centers. In these cases the absence of results or - -
  • the first of these reactions has been specifically designed to analyze the DXS7423, GATA31E08, DXS6789 and DXS 101 loci, from fragments that exceed 169 bp base pairs. While the second reaction allows the analysis of loci DXS7133, DXS7424, GATA165B12 and DXS8378, even from fragments that exceed 1 1 1 bp.
  • Table 4 also shows a comparative study of the base pair sizes of the amplicons corresponding to miniSTR loci of the X chromosome in the main multiplex reactions of the prior art.
  • the miniSTRs are the products resulting from the redesign of primers, which join regions as close as possible to the structure of the STR, with the purpose of obtaining amplicons of reduced size.
  • Table 4 List of the main miniSTR loci of the prior art. The base pair size of each amplicon is detailed when analyzed by the main multiplex reactions.
  • a main aspect of the invention relates to a method for obtaining the genetic profile of an individual comprising the analysis, in a DNA extract from said individual, by means of a multiplex amplification reaction of at least 4 STRs loci of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 where
  • At least one of the 4 STR loci is selected from the group formed by the loci
  • At least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
  • the invention provides a kit comprising pairs of specific primers to amplify at least 4 STR loci selected from the group formed by loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS10079, wherein a) at least 1 of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS 10074, DXS6789 and DXS6809 loci; Y
  • the invention relates to a set of primer pairs comprising at least 4 primer pairs aimed at amplifying 4 STR loci of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 wherein a) at least one of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS 10074, DXS6789 and DXS6809 loci; Y
  • At least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
  • the use of the set of primer pairs of the invention is contemplated to obtain the genetic profile of an individual, to determine kinship relationships between individuals or to identify human remains,
  • the invention relates to a pair of primers selected from the group consisting of the following oligonucleotide pairs - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
  • Figure 1 corresponds to a graph called electropherogram showing the genetic profile of an individual for the STRs analyzed by the set of primers of the invention using an automatic AB310 Genetic Analyzer (Applied Biosystems ® ) sequence analyzer.
  • panels can be observed, each corresponding to those pairs of primers marked with the same fluorescent locus.
  • Each panel shows the intensity of the signal detected in the Relative Fluorescence Units (RFU, relative fluorescence unit) on the Y axis;
  • the X axis corresponds to the size in base pairs. So, - -
  • the first panel corresponds to the results obtained for the products of STRs amplified with primers marked with 6-FAM TM (directed to the loci DXS6799 and DXS 10074, the second panel to those marked with VIC TM (DXS7132 and DXS6801), the third to NED TM (loci DXS6789 and DXS6809) and fourth panel results for loci STRs labeled with the fluorochrome PET ® (DXS 10075 and DXS 10079) are shown.
  • Figure 2 is a graphic representation showing the design of the set of primer pairs called miniX.
  • the boxes represent the amplified sizes for each locus Loci marked with different color are presented in different gray scales
  • the respective tides are indicated in the right part of the figure
  • Figure 3 is a comparison of the The method obtained by miniX and Decaplex, in the analysis of the loci shared by both reactions, from 24 paraffin samples.
  • Figure 4 is a comparison of the yield obtained by miniX and Sextaplex, in the analysis of the loci shared by both reactions, from 24 paraffin samples.
  • Said feature allows the application of this invention in the resolution of complex paternity cases from highly degraded DNA samples more effectively than commercial kits developed to date for the analysis of the aforementioned X chromosome loci.
  • the terms “genetic profile” and “genetic fingerprint” have the same meaning and can therefore be used interchangeably throughout the description.
  • the “genetic profile” is a set of sequences of characteristic bases of the genetic material that allow differentiating an individual from another. STR loci
  • STRs sequences or "STRs loci” means those DNA sequences, also called microsatellites, that contain 4 bp repeats (Butler JM, Biotechniques. 2007).
  • the analysis of the STRs loci in the genome presents multiple applications that include, but are not limited to, obtaining genetic profiles, kinship diagnoses, determining the origin of a sample or tissue, identification of cadavers, population genetics studies, tests of zygosity in twins, monitoring of bone marrow transplants, evaluation of the traceability of biological samples of human origin, identification of mixtures present in a sample and determination of the number of contributors of human origin to a mixture and their contribution relative to the mixture.
  • PCR corresponds to the polymerase chain reaction acronym whereby millions of copies of the desired DNA regions can be obtained. It is characterized by the use of pairs of primers that delimit the region from which millions of copies will be made, which is also known as "amplifying DNA" during PCR.
  • the PCR is composed of a certain number of cycles, in turn composed of three phases in which the DNA strands are separated, the primers are joined and the new DNA strands are elongated. In each cycle, if the reaction efficiency is 100%, exponential growth of the DNA fragments subject to amplification occurs.
  • multiplex amplification reaction is understood as the PCR reaction in which more than one DNA sequence is amplified in the same reaction, by using two or more pairs of primers in a single tube together with the rest. of the reaction reagents in order to simultaneously amplify multiple DNA sequences.
  • oligonucleotide refers to the sequence of nucleotide bases linked by phospho-diester bonds, usually not greater than 50 nucleotides.
  • primer or “first” or “oligonucleotide” (“oligo”) is understood as the nucleotide sequence from which DNA polymerase initiates the synthesis of a new DNA molecule.
  • the primers are short nucleotide sequences, approximately 15-24 nucleotides in length that can be aligned with a strand of target DNA thanks to the complementarity of bases to form a hybrid between the primer and the target strand of DNA. Then, the DNA polymerase enzyme can extend the primer along the DNA strand. Methods for preparing and using primers are described, for example in Sambrook et al., 2001 and Ausubel et al., 1999.
  • primer pair or “first pair” is understood as the set of two primers which, when used in the same amplification or PCR reaction, allow multiple copies of a DNA target sequence to be obtained.
  • Each of the primers hybridizes with the target sequence, so that the bounded nucleotide sequence is amplified by each pair of primers.
  • the extent of the primers during the PCR cycles determines the 2 N exponential multiplication of the nucleotide sequence bounded by the primers, N being the number of cycles of the PCR reaction.
  • biological sample means any matter that contains a nucleic acid, for example, DNA.
  • DNA or “genomic DNA” is understood as the genetic material of living organisms that controls inheritance and is located in the nucleus of cells.
  • DNA extract is understood when, after subjecting the biological sample to a method of extraction, separation, purification or cloning of DNA, among others, it is obtained as a result either dry, in solution, bound or not to other molecules, adhered or not to various substances or beds, matter in which the DNA is in a greater relative proportion with respect to the rest of the molecules present, compared to the biological starting sample.
  • DNA extract refers to DNA extracted from any biological sample that contains human DNA, whether from a living or dead individual, fetus, organs, tissues or cells.
  • the term "individual” refers to a human being of any age or race, who in the context of the present invention may be alive or dead.
  • the inventors have designed a pair of primers, henceforth, "pairs of primers of the invention” or “miniX”, which allows obtaining the genetic profile of the STRs loci (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 and DXS 10079) of an individual, even from highly degraded DNA samples, and is applicable even to complex kinship analysis.
  • MiniX is characterized by allowing a high number of STR loci to be analyzed by small amplified amplifiers. So, it has been specifically designed to enable the amplification of 8 STRs loci, from DNA fragments that exceed 220 bp. It stands out for being the only system currently available that allows analyzing all the STRX DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci, in a single multiplex reaction. In addition, it includes amplifiers smaller than those available in the state of the art in 6 of the 8 STR loci included.
  • the primer pairs have been designed so that their application allows obtaining the genetic profile of an individual that comprises the combination of at least 4 to 8 STR loci.
  • the designed primer pairs have the additional technical characteristic that, if desired, they can be used simultaneously in combinations of 4 or up to 8 primer pairs in a multiplex amplification reaction to obtain a genetic profile composed of 4 or more STRs loci up to a total of 8 STR loci whose analysis of high interest in Forensic Genetics and Population Genetics, without limiting this interest to these areas.
  • STRs loci analyzed in the present invention as well as the pairs of primers designed for identification are shown in Table 5. This same table details the minor to major allele of the STR that will be considered by this analysis (column: alleles) as well. as the maximum and minimum possible size for each STR.
  • Example 1 details the procedure followed in the design of the set of primer pairs of the invention. - -
  • Example 1 the design of the primer pairs of the present invention was carried out by searching the flanking sequences at each STR locus. Subsequently, the Perlprimer program was used. Once the primer pairs were obtained, a polymerase amplification reaction was carried out on a DNA extract using said primer pairs after which, the genetic profile of the individual to whom the DNA extract belonged reliably was obtained, precision and with a discriminating power superior to the genetic profiles obtained by other methods from highly degraded DNA samples, as illustrated in example 2.
  • Table 5 Summary of the sequence of primers in the 'to 3 direction 'designed for the amplification of each STR in the combination called as miniX (column: sequence 5 ' - 3 ' ). The variation (rs945048 A / T) of the degenerate primers sequence is underlined and the G base added to the sequence appears in bold for the DXS 10075 locus.
  • a main aspect of the invention relates to a set of primer pairs, hereafter "set of primer pairs of the invention", comprising at least 4 primer pairs aimed at amplifying 4 loci STRs of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079, where - -
  • At least one of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS10074, DXS6789 and DXS6809 loci; Y
  • the set of primer pairs of the invention comprises at least 5, 6, 7 or 8 specific primer pairs for the STR loci of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079.
  • primer pairs are selected from the group consisting of the following oligonucleotide pairs:
  • the invention relates to a pair of primers selected from the group consisting of the following oligonucleotide pairs:
  • uses of the set of primer pairs of the invention include, but are not limited to, obtaining genetic profiles, kinship diagnoses, determining the origin of a sample or tissue, identification of cadavers, population genetics studies, evidence of Zygosity in twins, monitoring of bone marrow transplants, evaluation of the traceability of biological samples of human origin, identification of mixtures present in a sample, determination of the number of contributors of human origin to a mixture and their contribution relative to the mixture.
  • the use of the set of primer pairs of the invention is contemplated to obtain the genetic profile of an individual, to determine kinship relationships between individuals or to identify human remains.
  • the present invention is based on the design of a pair of primers that allow obtaining the genetic profile of an individual based on a combination of at least 4 STRs.
  • Another main aspect of the invention relates to a method, hereinafter "method of the invention", to obtain the genetic profile of an individual comprising the analysis, in a DNA extract from said individual, by means of a multiplex amplification reaction, of at least 4 STRs loci from the group consisting of the DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci, where a) at least one of the 4 STRs loci is selected from group formed by loci DXS6799, DXS 10074, DXS6789 and DXS6809; Y
  • At least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
  • the primer pairs have been designed in such a way that it is possible to use them in the analysis of 4 or more, up to a total of 8 STRs loci, (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079).
  • STRs loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079.
  • the set of primer pairs aimed at obtaining the genetic profile of an individual is directed to the analysis of at least 5, 6, 7 or 8 STR loci of the group formed by the loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079.
  • the primer pair employed in the multiplex amplification reaction specific to each of the STR loci analyzed is the oligonucleotide pair shown in the sequences.
  • the implementation of the method of the invention requires obtaining a DNA extract that will ultimately come from a biological sample that will be adequately treated to obtain said DNA extract.
  • the DNA extract will come from the individual whose genetic profile is to be obtained, or from the individuals whose kinship relationship wants to be determined.
  • the present invention is especially indicated to resolve those kinship relationships in which the biological samples of some of the people involved are not available.
  • the method of the invention is directed to the identification of human remains, the DNA extract will come from the human remains that are to be identified.
  • the term "human remains” includes any biological sample from a human being, said human residue being able to be preserved in formol, frozen, dried, fixed in paraffin, in a state of decomposition, degradation and / or rot, between others.
  • samples from which DNA can be obtained are, without limitation, biological fluids (blood, saliva, urine, sperm, etc); epidermis, dandruff, hair, feces, a vaginal sample, a tissue sample, burned tissues, etc.
  • biological fluids blood, saliva, urine, sperm, etc
  • epidermis dandruff, hair, feces, a vaginal sample, a tissue sample, burned tissues, etc.
  • the most suitable samples for obtaining DNA extracts useful in the identification of human remains include, among others, root hairs, compact bone, tooth, soft tissues and blood.
  • the DNA extract comes from a sample of blood, hair, saliva, epidermis, sperm, dandruff, ashes, a vaginal sample and a tissue sample,
  • the fraction of DNA suitable for the implementation of the invention is nuclear DNA. DNA extraction may be performed using any method known to those skilled in the art (Sambrook et ai, 2001 "Molecular Cloning: A Laboratory Manual", 3rd ed, Cold Spring Harbor Laboratory Press, NY, Vol . 1.
  • kits - -3) including without limitation, density gradient centrifugations, two-phase extraction using aqueous phenol or chloroform with ethanol, column chromatography, methods based on the ability of DNA to bind on glass surfaces and / or silicates, as preparations of diatomaceous earth or glass beds, using kits - -
  • the DNA extract is quantified and normalized to obtain equal amounts of DNA in each sample in case the amount of DNA is sufficient for it.
  • the DNA extract from the biological sample After obtaining the DNA extract from the biological sample, it is subjected, at least, to a multiplex amplification reaction using the set of primer pairs of the invention.
  • the amplification of the different STRs loci requires specific reaction conditions and procedures for each of the pairs of primers used, which can be achieved by systematic variation of each parameter.
  • the number of cycles and the alignment temperature used in the PCR reaction must be suitable for obtaining results by each of the first set of primers. Parameters such as the concentration of primers are specific to each primer and have been adjusted in the validation of the primer set.
  • the primers offer results in a wide range of concentrations, although the optimal concentrations for each pair of primers are shown in Table 6.
  • a multiplex amplification reaction requires a series of reagents, including, but not limited to, the template DNA, the enzyme DNA polymerase, at least two pairs of primers (each primer being each pair complementary to one of the two strands of the DNA), deoxynucleotide triphosphates (dNTPs), magnesium chloride (MgC12), reaction buffer and optional additives, which can be added separately by mixing in the laboratory or purchased previously mixed, as is the case of Multiplex PCR master Mix (Qiagen, Hilden, Germany), or Kapa2GTMFast Multiplex PCR kit (apa Biosystems, Inc., USA), to which the primer pairs are added in the appropriate concentrations and the template DNA.
  • dNTPs deoxynucleotide triphosphates
  • MgC12 magnesium chloride
  • the PCR is carried out in a thermal cycler that performs the cycles in the exact times and temperatures programmed, such as the hybridization temperature or the melting temperature.
  • the melting temperature of the multiplex amplification reaction comprising oligonucleotides SEQ ID NO: 1 to SEQ ID NO. 17 is from 57 to 63 ° C as calculated using the Perlprimer software (http://perlprimer.sourceforge.net/).
  • the priming of the primers participating in said multiplex amplification reaction can be carried out in order to be able to subsequently detect the amplified fragments.
  • the marking of amplification products can be carried out by conventional methods. Said marking can be direct, for which fluorophores can be used, for example, Cy3, Cy5, fluorescein, alexa, etc., enzymes, for example, alkaline phosphatase, peroxidase, etc., radioactive isotopes, for example, 33P, 1251, etc., or any other marker known to the person skilled in the art.
  • said marking can be indirect through the use of chemical, enzymatic methods, etc .
  • the amplification product may incorporate a member of a specific binding pair, for example, avidin or streptavidin conjugated with a fluorochrome (locus), and the probe binds to the other member of the specific binding pair, for example, biotin (indicator), the reading being carried out by fluorimetry, etc.
  • the amplification product may incorporate a member of a specific binding pair, for example, an anti-digoxigenin antibody conjugated to an enzyme (locus), and the The probe binds to the other member of the specific binding pair, for example, digoxigenin (indicator), etc., the enzyme substrate is transformed into a luminescent or fluorescent product and the reading is carried out by chemo-luminescence, fluorimetry, etc.
  • the marking of the amplification product is carried out by marking, at one of its ends, one of the oligonucleotides of each primer pair.
  • the oligonucleotide mapping is selected from the group consisting of a radioisotope, a fluorescent material, digoxigenin and biotin.
  • 5-FAM 5-carboxyfluorescein
  • 6-FAM t-FAM tetrachlorinated analog
  • HEX 6-FAM hexachlorinated analog
  • TAMRA 6- carboxytetra
  • the amplification products or amplicons can be separated.
  • Virtually any conventional method can be used within the framework of the invention to separate products from -
  • Techniques for separating amplification products are widely described in the state of the art, such as in Sambrook et al., 2001 (cited ad supra). Techniques for separating amplification products are, for example, submerged electrophoresis with Methafor gels, polyacrylamide gels electrophoresis, capillary electrophoresis, etc.
  • the size of the separated fragments is identified, for which any of the methods of identification of amplification fragments known in the state of the art can be used, such as hybridization with labeled probes (for example with a fiuorophore) that will be detected by a detector and processed by a computer system, staining, for example, with ethidium bromide, silver staining, etc.
  • labeled probes for example with a fiuorophore
  • staining for example, with ethidium bromide, silver staining, etc.
  • the invention relates to a kit useful for the implementation of the method of the invention, comprising the set of primer pairs of the invention comprising 4 or more primer pairs aimed at amplifying the STRs loci (DXS6799 , DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I, DXS 10075 and DXS 10079).
  • kit hereinafter kit of the invention, comprising pairs of specific primers to amplify at least 4 STR loci selected from the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I, DXS 10075 and DXS 10079, where at least 1 of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS 10074, DXS6789 and DXS6809 loci; and at least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
  • kit hereinafter kit of the invention, comprising pairs of specific primers to amplify at least 4 STR loci selected from the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I,
  • the kit of the invention comprises at least 5, 6, 7 or 8, pairs of primers specific for the STR loci of the group formed by loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 and DXS10079 .
  • the primer pair used in the multiplex amplification reaction specific to each of the STR loci analyzed is the oligonucleotide pair shown in the sequences.
  • the kit of the invention in addition to comprising the set of primer pairs of the invention, may optionally include the reagents necessary to carry out the multiplex amplification reaction, including, without limiting to, deoxynucleotides triphosphate (dNTPs), divalent and / or monovalent ions, a buffer solution (buffer) that maintains the proper pH for the functioning of DNA polymerase, DNA polymerase or mixture of different polymerases, etc.
  • dNTPs deoxynucleotides triphosphate
  • buffer solution buffer
  • the kit of the invention does not comprise the reagents necessary to practice the method of the invention, these are commercially available and can be found as part of a kit.
  • any commercially available kit containing the reagents necessary to carry out an amplification reaction can be used successfully in the practice of the method of the invention. As shown in the examples, in the case of the present invention these reagents are previously mixed in the Multiplex PCR master Mix reagent (Qiagen, Hilden, Germany). - -
  • the priming of the primers can be carried out in order to be able to subsequently detect the amplified fragments.
  • the kit of the invention may comprise the first set of primer pairs of the invention wherein one of the oligonucleotides of each pair of primers is labeled at one of its ends or, alternatively , may comprise the reagents necessary to carry out the priming of the primers.
  • the kit of the invention further comprises the reagents necessary to label the nucleotide pairs.
  • one of the oligonucleotides of each pair of primers is labeled at one of its ends.
  • the markers used in the oligonucleotide mapping select from the group consisting of a radioisotope, a fluorescent material, digoxigenin and biotin.
  • the fluorescent material is selected from the group consisting of 5-carboxyfluorescein (5-FAM), 6-FAM, t-FAM tetrachlorinated analog (TET), 6-FAM hexachlorinated analog (HEX), 6- carboxytetramethylrodamine (TAMRA), 6-carboxy-X-rhodamine (ROX), 6-carboxy-4 ', 5'-dichloro-2', 7'-dimethoxyfluorescein (JOE), NED (ABI), Cy-3, Cy-5, Cy-5.5, fluorescein-6- isothiocinate (FITC) and tetramethylrodamine-5-isothiocinate (TRITC).
  • the kit of the invention is useful in the implementation of the kit of the invention is useful in the implementation of the kit of the invention.
  • Example 1 the validation of miniX is performed, for use in human identification.
  • Example 1 the optimization of the primer sets and the parameters of the PCR reactions is detailed, as well as the studies of the ratio between the height of heterozygotes (PHR), stutter bands (stutter bands) ) and sensitivity.
  • PHR heterozygotes
  • stutter bands stutter bands
  • Example 2 In the second example, the validation of the method of the invention comprising the multiplex amplification reaction is shown for use in the analysis of highly degraded DNA samples, in order to demonstrate that the invention is suitable for use. In this type of samples.
  • miniX is a suitable tool for obtaining human genetic profiles.
  • Saliva samples were taken from 439 healthy individuals: 365 residents in Santander (Cantabria, Spain) grouped into 1,116 families and 74 inhabitants of Vega de Pas (Cantabria, Spain) grouped into 22 families. In all cases the families were constituted at least by paternal grandfather, mother and son. DNA extraction and quantification
  • DNA extracts from population samples were obtained by extraction by Prep Mini Spin kit (GE Healthcare Spain, Barcelona,
  • Quantification of DNA extracts was performed using Quant-iT TM dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA).
  • the Perlprimer program http://perlprimer.sourceforge.net/) was used to design new primers that amplify 8 STR loci (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079), based on the reference sequences whose access numbers to GeneBank are shown in Table 7.
  • the flanking regions to the STRs analyzed were studied using SNPblast www.ncbi.nlm.nih.gov/SNP/snpblastByChr.html) in order to avoid variable positions in the junction region of all designed primers.
  • the amplifiers range from 101 to 219 bp, to cover a large number of the alleles contained in the reference publications detailed in Table 1, made based on the information collected in ChrX-STR.org 2.0 [http: // www .chrx-str.org].
  • each amplifier product was analyzed mixed with 9 ⁇ of Hi-Di TM Formamide (Applied Biosystems ® , Foster City, CA) and 0.3 ⁇ of GeneScan TM 500 LIZ ® Size Standard (Applied Biosystems ® , Foster City, AC). After the denaturation of the amplified (5 minutes at 95 ° C) they were cooled (5 minutes at 4 ° C) and separated in an ABI PRISM 310 Genetic Analyzer (Applied Biosystems ® , Foster City, CA), Electrophoresis results were analyzed using Genmapper software version 3.2 (Applied Biosystems ® , Foster City, CA).
  • Table 7 shows a wide range of alleles for each locus included in miniX.
  • the alleles described in the main population groups have been considered according to the information collected in ChrX-STR.org 2.0 [http://www.chrx-str.org].
  • 37 primers were designed from which those capable of producing amplifiers of the smallest possible size were chosen, which in no case exceeded 220 bp, whose melting temperatures were between 57.5 and 60.5 ° C and that hybridize in regions lacking SNPs ⁇ Single Nucleotide Polymorphism) and INDELS (Insertions / deletions) described to date in NCBI (http://www.ncbi.nlm.nih.gov/snp/).
  • the degenerate primers (degenerate primers) design for the DXS 10075 locus was necessary to allow hybridization to the primer binding site, because an SNP (rs945048 A / T) was found close to the repeat unit of said STR .
  • SNP rs945048 A / T
  • first phase of optimization singleplex PCR amplifications of each locus were performed.
  • second optimization phase various sets of multiplex primers were tested.
  • the allele ranges of adjacent loci in size were spaced in order to avoid overlaps between alleles corresponding to different loci to ensure proper genotyping.
  • duplex A DXS6799 and DXS 10074; duplex B: DXS6789 and DXS6809; duplex C: DXS7132 and DXS6801 and duplex D: DXS 100075 and DXS 10079) were selected.
  • primers were designed so that a total of 8 STRs loci could be analyzed in a single multiplex reaction: (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079).
  • the optimization of the amplification parameters such as the optimal concentration of primers, hybridization temperature, number of cycles and extension time, was carried out by studying the electro ferograms in which the height of the peaks was evaluated, the balance in heterozygous thereof and incomplete adenylation.
  • concentration of each pair of primers was tested between 0.04 ⁇ and 0.6 ⁇ , so that in each case, below the optimum concentration an increase in the height of the peaks was observed as that the concentration of primers was increased. While at the same time, in concentrations higher than the one considered optimal, an increase in both imbalance in heterozygosis and incomplete adenylation was detected.
  • the hybridization temperature of the multiplex PCR reaction was then optimized.
  • the increase in hybridization temperature produced a gradual decrease in incomplete adenylation, but also in the height of the peaks.
  • the best results were obtained at the hybridization temperature of 58 ° C.
  • miniX has proven to be a balanced and specific multiplex reaction, capable of amplifying 8 STRs loci, from 0.5 ng of template DNA (Figure 1), by the following amplification conditions: an initial denaturation cycle during 15 minutes at 95 ° C, 30 cycles of 30 s at 94 ° C, 90 s at 58 ° C and 60 s at 72 ° C, followed by the final 60 minute extension cycle at 60 ° C.
  • MiniX has proven to be a balanced and specific multiplex reaction, capable of amplifying 8 STRs loci. In this way miniX is the only reaction capable of analyzing simultaneously - -
  • miniX ftability has been verified by concordance studies between the genetic profiles determined by this system and those obtained through widely used and validated pre-existing systems such as Decaplex and Sextaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 ( 3): 227-234; Casta ⁇ eda et al., 2012 J. Forensic Sci. 57 (1): 192-195). In this sense, 100% concordance was observed between the results of the three reactions compared. Sextaplex shares 6 of the STR loci included in miniX (DXS 10074, DXS6789, DXS6809, DXS6801, DXS 10075 and DXS 10079).
  • miniX is a system of high robustness and reliability in obtaining genetic profiles, which makes them a useful tool for use in human identification.
  • the small size of its amplifiers smaller in its totality at 219 bp suggests that the present invention has a high analysis capacity of the DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
  • Validation of the method of the invention comprising a multiplex amplification reaction using sets of miniX primer pairs for use in the analysis of highly degraded DNA samples - -
  • K562 control DNA (Promega® Corporation, USA) was used to perform sensitivity assays. This sample was quantified using Quant-iT TM dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA) according to the manufacturer's specifications and was diluted to 0.5 ng / ⁇ .
  • Saliva samples were taken from 439 healthy individuals: 365 residents in Santander (Cantabria, Spain) grouped into 1,116 families and 74 inhabitants of Vega de Pas (Cantabria, Spain) grouped into 22 families. In all cases the families were constituted at least by paternal grandfather, mother and son. -
  • DNA extracts from population samples were obtained by extraction by Prep Mini Spin kit (GE Healthcare Spain, Barcelona, Spain) and those from paraffin by cobas® DNA Sample Preparation Kit (Roche Roche Diagnostics SL, Barcelona, Spain). Quantification of DNA extracts was performed using Quant-iT TM dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA).
  • the amplification was performed in a GeneAmp ® 9700 PCR System thermocycler (Applied Biosystems, Foster City, CA), under the following conditions: an initial denaturation cycle for 15 minutes at 95 ° C, 30 cycles of 30 s at 94 ° C, 90 at 58 ° C and 60 s at 72 ° C, followed by the final 60 minute extension cycle at 60 ° C.
  • stuttering bands which are allelic products that differ from the true allele only in a unit of repetition.
  • the determination of stuttering alleles in both homozygous and heterozygous individuals that differed in size by more than 4 bp was made by calculating the percentage of the stutter allele's height relative to the actual peak's height.
  • the calculation of the relative intensity of heterozygous peaks (“Peak Height Ratio" or PHR) was done by dividing the height of the smallest of the peaks by the height of the largest of the heterozygotes of each locus.
  • control DNA 562 was analyzed in duplicate (Promega ® Corporation, USA). DNA concentrations of 1 ng, 500 pg, 200 pg, 100 pg, 75pg, 62.5 pg, 50 pg, 25 pg, 20 pg, 10 pg and 5pg were used.
  • the least amount of DNA that allowed to obtain complete profiles by duplicate miniX analysis was 20 pg. Even amounts of DNA in the range of 10 to 20 pg, allowed the analysis of 5 STR loci (a fixed core of 4 STRs loci: DXS6799, DXS6789, DXS6809 and DXS 10079; and DXS 10075 or DXS 10074, depending on the replica ) by alleles whose intensity was in the range 42-466 RFUs. While the remaining 2 STR loci (DXS7132, DXS6801) presented allelic losses due to stochastic effects or did not offer results at more than 40 RFUs in any of the duplicates. Comparative study of the design strategies of the primer sets of the present invention with respect to prior art methods
  • the size of the amplicons of a multiplex STR system is critical for obtaining - -
  • table 1 1 the discrimination power obtained by miniX, Decaplex and Sextaplex is detailed, after the analysis of the loci shared between miniX and said reactions, from highly degraded DNA fragments: miniX vs. Decaplex (DXS6789, DXS6809 and DXS7132); and miniX vs. sextaplex (DXS 10074, DXS6789, DXS6809, DXS6801, DXS 10075 and DXS10079).
  • the values obtained correspond to the analysis of DNA fragments of 220 bp.
  • the intensity of the signal of an allele is related to its ability, so that genotyping based on alleles whose height does not exceed 50-100 RFUs (Relative Units of Fluorescence) is usually not performed. That is why the performance in the analysis of highly fragmented DNA samples has been evaluated based on two variables: A) the percentage of samples in which each STR has been genotyped, discarding those alleles of height less than 50 RFUs; and B) the percentage of samples in which the genotyping corresponds to alleles of height greater than 200 RFUs, indicating extra reliability of the result.
  • miniX has a higher overall performance than Decaplex in 2 of the 3 shared loci, with the exception of the DXS7132 locus, which has been genotyped by Decaplex in 92% of the samples compared to 88 % in the case of miniX. Although, in this locus, said 4% difference corresponds to alleles whose height does not exceed 200 RFUs. On the other hand, miniX shows a global performance superior to Sextaplex in the 6 shared STR loci and a higher percentage of alleles above 200 RFUs (Figure 4).
  • the percentage values of stuttering alleles of mean, median, standard deviation, minimum and maximum values of the method of the invention are adjusted to those obtained by other research groups in the validation of other STRs loci analysis systems of Chromosome X (Asamura et al., 2006 Int. J. Legal Med. 120: 174-181, in the validation of other multiplex reactions of autosomal STRs such as I-DNA-1 (Odriozola et al., 201 1 Int. J. Legal Med. 125 (5): 685-94), I-DNA-2 (Odriozola et al., 2012 Int. J. Legal Med. 126 (1): 167-72) and geneRESMPX-3 (Schlenk et al, 2004. Int J Legal Med, 1 18 (1): 55-61) Together, the low percentages of stuttering alleles obtained for miniX favor the correct genotyping of the samples.
  • the PHR values define the balance in the heterozygous amplification.
  • miniX a lower average PHR is observed than that reported for other identification systems such as I-DNA-1 (Odriozola et al., 201 1 Int. J. Legal Med. 125 (5): 685-94), I- DNA-2 (Odriozola et al., 2012 Int. J. Legal Med. 126 (1): 167-72), geneRESMPX-3 (Schlenk et al, 2004. Int J Legal Med, 1 18 (1): 55- 61), MiniFiler TM PCR Amplification Kit (Mulero et al., 2008. J. Forensic Sci.
  • miniX shows a lower standard mean deviation than the one reported for Minificaler TM PCR Kit (Applied Biosystems, Foster City, CA) (12.02 vs. 33.47) (Mulero et al., 2008 J Forensic Sci. 53 (4): 838-52). It has not been possible to compare the percentage of stuttering alleles and PHR with reactions that include the STR loci of the reaction object of the invention, such as Decaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 (3): 227 - 234) and Sextaplex (Casta ⁇ eda et al., 2012 J. Forensic Sci.
  • miniX The sensitivity of miniX has been compared with that reported for other STRs loci analysis systems and more specifically for those that include XS miniSTRs.
  • 5 (5) 415-421) require amounts greater than MiniX, at least 200 pg of template DNA to obtain complete profiles, and 100 pg for profiles with loss of 1-2 markers.
  • DNA extracts analyzed in forensic laboratories are often characterized by containing very small amounts of DNA, which makes it difficult to obtain genetic profiles of high discriminatory power after analysis using a multiplex STR system.
  • the size of the amplicons of a STR multiplex system is critical for obtaining genetic profiles from highly degraded biological samples (Budowle et al., 2009 Croat. Med. J. 50 (3): 207-17).
  • MiniX stands out for being the only system currently available that allows analyzing all the STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS10079 loci, in a single multiplex reaction, also including amplified smaller than those available in the state of the art in 6 of the 8 STR loci included (Table 10). The exception is the DXS 10074 and DXS6801 locus that results in amplifications 27 and 37 bp greater than those obtained by the reactions developed by Becker et. al, 2008 Forensic. Sci. Int. Genet. 2 (1): 69-74 and Casta ⁇ eda et al., 2012 J.
  • miniX the smallest possible amplifications are produced for the DXS6809 locus (175-219 bp), having been designed in the area directly adjacent to the repetitive region of said locus. The rest of the STRs loci give rise to amplitudes less than 200 bp.
  • miniX represents the only alternative in miniSTR format for the amplification of the DXS6799, DXS 10075 and DXS 10079 loci. - -
  • miniX achieved greater performance than Decaplex in two of the 3 shared loci. While in the DXS7132 locus, both reactions obtained a yield of 88% by means of signals that exceeded 200 RFUs and Decaplex obtained an additional 4% by means of signals that did not reach said intensity. On the other hand, miniX exceeded the performance obtained through Sextaplex in the 6 STR loci shared by both reactions.
  • this validation includes both stuttering alleles, PHR and sensitivity assays, as well as comparative studies of design strategies and analysis of highly degraded DNA samples.
  • the results obtained demonstrate that the performance of the present invention in the analysis from highly degraded and / or scarce DNA samples of the DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci is superior to the prior art methods.

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Abstract

The invention relates to a method for obtaining an individual's genetic profile, comprising the analysis of an extract of DNA from the individual, using a single multiplex amplification reaction of the combination of 8 STR loci of the X chromosome, formed by DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 and DXS10079. The invention also relates to a group of pairs of primers specifically designed for the amplification of each of the 8 STR loci analysed in a single multiplex reaction and to a kit comprising said primers for carrying out the method.

Description

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MÉTODO PARA LA OBTENCIÓN DEL PERFIL GENÉTICO DE UN INDIVIDUO MEDIANTE EL ANÁLISIS DE LOCI DE CROMOSOMA X METHOD FOR OBTAINING THE GENETIC PROFILE OF AN INDIVIDUAL THROUGH THE ANALYSIS OF CHROMOSOME X LOCI
CAMPO DE LA INVENCIÓN FIELD OF THE INVENTION
La invención se relaciona con un método para obtener el perfil genético de un individuo que comprende el análisis de 4 o más loci STRs, hasta un total de 8 loci, todos ellos localizados en el cromosoma X, en un extracto de ADN de dicho individuo mediante una reacción de amplificación multiplex. Asimismo, la presente invención también se dirige a un kit que comprende las parejas de cebadores para la puesta en práctica del método de la invención. Tanto el método como el kit aquí descritos son de aplicación en la identificación de individuos en el área de la genética forense, así como en genética de poblaciones, antropología y biomedicina. ANTECEDENTES DE LA INVENCIÓN The invention relates to a method for obtaining the genetic profile of an individual comprising the analysis of 4 or more STRs loci, up to a total of 8 loci, all located on the X chromosome, in a DNA extract of said individual by a multiplex amplification reaction. Likewise, the present invention is also directed to a kit comprising the pairs of primers for the implementation of the method of the invention. Both the method and the kit described here are applicable in the identification of individuals in the area of forensic genetics, as well as in population genetics, anthropology and biomedicine. BACKGROUND OF THE INVENTION
Actualmente la obtención de perfiles genéticos mediante el análisis de loci STRs (Short Tándem Repeats) autosómicos plantea en ocasiones problemas técnicos que se traducen en no poder ofertar un resultado concluyente de probabilidad de paternidad o parentesco que es solicitado por los Tribunales de Justicia. Ello acontece fundamentalmente en la determinación de casos complejos: la falta de algún progenitor o de ambos existiendo abuelos/tíos. En estos casos se hace necesario el análisis nuevamente de los individuos con otros kits de STRs de cromosomas autosómicos y STRs de cromosomas sexuales (STRs del cromosoma X y del Cromosoma Y) con el fin de aumentar el número de STRs analizados y alcanzar una probabilidad suficiente. Currently obtaining genetic profiles through the analysis of autosomal STRs (Short Tandem Repeats) loci sometimes raises technical problems that result in not being able to offer a conclusive probability of paternity or kinship that is requested by the Courts of Justice. This occurs primarily in the determination of complex cases: the lack of a parent or both of them existing grandparents / uncles. In these cases, it is necessary to analyze again the individuals with other kits of autosomal chromosome STRs and sex chromosome STRs (X chromosome and Y chromosome STRs) in order to increase the number of STRs analyzed and reach a sufficient probability .
En numerosas ocasiones a lo anteriormente expuesto se añade otra circunstancia que dificulta el análisis de individualización con los STRs convencionales y es la degradación del ADN de la muestra objeto de estudio. On numerous occasions, another circumstance is added that makes the analysis of individualization difficult with conventional STRs and is the degradation of the DNA of the sample under study.
Por todo lo anterior resulta prioritario desarrollar nuevas metodologías de obtención de perfiles genéticos alternativos a los ya existentes en el estado de la técnica y que superen los inconvenientes actuales. - For all the above it is a priority to develop new methodologies for obtaining alternative genetic profiles to those already existing in the state of the art and that overcome the current drawbacks. -
El cromosoma X comprende 155 Mb y representa el 5% del total del material genético de las células. Contiene aproximadamente del orden de 1 100 genes. Tan solo un 1 .7% de este cromosoma codifica proteínas funcionales, presentando un elevado contenido de ADN no codificante repetitivo (Ross et al., 2005 Nature 434: 325- 337). Parte de esta fracción son regiones cortas repetidas en tándem o "short tándem repeats" (STR). Hasta la fecha, se han descrito más de cincuenta STRs en el cromosoma X cuyo análisis es fundamentalmente de interés entre otras, en Genética Forense y en las disciplinas anteriormente mencionadas (Gusmao et al., 2012 Methods Mol. Biol. 830: 57-71). El análisis de marcadores microsatélites denominados STRs (Short Tándem Repeats) es hoy en día la técnica de referencia para la obtención de perfiles genéticos destinados a identificación de individuos, determinación de parentesco o criminalística. The X chromosome comprises 155 Mb and represents 5% of the total genetic material of the cells. It contains approximately 1 100 genes. Only 1.7% of this chromosome encodes functional proteins, presenting a high content of repetitive non-coding DNA (Ross et al., 2005 Nature 434: 325-337). Part of this fraction are short regions repeated in tandem or "short tandem repeats" (STR). To date, more than fifty STRs have been described on the X chromosome whose analysis is fundamentally of interest among others, in Forensic Genetics and in the aforementioned disciplines (Gusmao et al., 2012 Methods Mol. Biol. 830: 57-71 ). The analysis of microsatellite markers called STRs (Short Tandem Repeats) is nowadays the reference technique for obtaining genetic profiles aimed at identifying individuals, determining kinship or crime.
Sin embargo, la eficacia de los STR autosómicos se ve reducida en la resolución de determinados casos de parentesco, tales como aquellos en las que la muestra de alguno de los miembros familiares no está disponible y la descendencia es femenina (Szibor et al., 2007 Forensic Sci. Int. Genet. 1 :93-97; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74). However, the efficacy of autosomal STRs is reduced in the resolution of certain cases of kinship, such as those in which the sample of one of the family members is not available and the offspring are female (Szibor et al., 2007 Forensic Sci. Int. Genet. 1: 93-97; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74).
En dichos casos, el análisis de STRs del cromosoma X constituye una herramienta complementaria de elevado interés (Zarrabeitia et al., 2002 Forensic Sci. Int. 129 (2):85-89; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74; Liu et al, 2008 Int. J. Legal Med. 122: 261 - 265). Así mismo, ha demostrado gran utilidad en la identificación de individuos. In such cases, the X-chromosome STR analysis is a complementary tool of high interest (Zarrabeitia et al., 2002 Forensic Sci. Int. 129 (2): 85-89; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74; Liu et al, 2008 Int. J. Legal Med. 122: 261-265). Likewise, it has demonstrated great utility in the identification of individuals.
Herencia del cromosoma X X chromosome inheritance
Ello se debe al particular modo de herencia del cromosoma X. Los hombres poseen un único cromosoma X y un único cromosoma Y, transmitiendo una copia exacta del Cromosoma X a todas sus hijas, tal como lo heredó de su madre y una copia exacta del cromosoma Y a todos sus hijos (Wakefield et al., 2006 Encyclopedia of life sciences; Burgoyne et al., 1982 Hum. Genet. 61 : 85-90). This is due to the particular mode of inheritance of the X chromosome. Men have a single X chromosome and a single Y chromosome, transmitting an exact copy of the X chromosome to all their daughters, as inherited from their mother and an exact copy of the chromosome. And to all his children (Wakefield et al., 2006 Encyclopedia of life sciences; Burgoyne et al., 1982 Hum. Genet. 61: 85-90).
Por lo que, el haplotipo del cromosoma X e Y paterno puede ser detectado respectivamente en la descendencia femenina y masculina. - - Therefore, the haplotype of the paternal X and Y chromosome can be detected respectively in the female and male offspring. - -
Las mujeres por su parte, contienen dos cromosomas X. Trasmiten uno de ellos a cada descendiente independientemente del sexo. Este cromosoma X que trasmite la madre puede ser una copia exacta de cualquiera de sus cromosomas o puede haber sufrido una recombinación entre los dos cromosomas X y ser distinto de la copia inicial que posee la mujer (Wakefield et al., 2006 Encyclopedia of life sciences). Women, meanwhile, contain two X chromosomes. One of them is transmitted to each offspring regardless of sex. This X chromosome that the mother transmits may be an exact copy of any of its chromosomes or it may have undergone recombination between the two X chromosomes and be different from the initial copy that the woman possesses (Wakefield et al., 2006 Encyclopedia of life sciences ).
Teniendo en cuenta que los padres van a transmitir una copia entera del Cromosoma X en ausencia de recombinación a todos sus descendientes femeninos, podemos determinar su haplotipo directamente. Given that the parents are going to transmit an entire copy of the X Chromosome in the absence of recombination to all their female offspring, we can determine their haplotype directly.
Aplicaciones del cromosoma X en diagnóstico de parentesco. Applications of the X chromosome in kinship diagnosis.
Esta característica del cromosoma X del varón permite estudios de paternidad de descendencia femenina, aún en ausencia del presunto padre constituyendo la principal ventaja del análisis de microsatélites del cromosoma X frente a sus homólogos autosómicos. El haplotipo del cromosoma X del padre será idéntico a uno de los cromosomas de la abuela paterna, por lo que si al menos un alelo de cada marcador analizado de la abuela no coincide con el de la nieta podrá descartarse la paternidad biológica. Estos análisis presentan una elevada probabilidad de exclusión. A su vez, en aquellos casos en los que la abuela tampoco esté disponible, puede reconstruirse su genotipo a través del estudio de los hermanos/as del presunto padre (Szibor et al, 2007 Forensic Sci. Int: Genet. 1 :93-97; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74). De un modo general, puede afirmarse que el estudio de STRs del cromosoma X de hermanos revela gran parte del genotipo materno (Szibor et al., 2003 Int. Congr. Ser. 1239: 815- 820). Por lo tanto, el análisis del cromosoma X también es de utilidad en el estudio de parentescos más distantes como el previamente mencionado abuela-nieta (Liu et al., 2008 Int. J. Legal Med. 122: 261- 265), e incluso en el estudio de grandes pedigríes familiares siempre que en cada generación exista al menos un descendiente femenino. La potencia de su análisis en este sentido, reside en la existencia de loci que por su proximidad física y sus características específicas constituyen bloques haplotípicos que se heredan juntos y se mantienen estables a través de las generaciones (Szibor et al., 2003 Int. Congr. Ser. 1239: 815- 820). - This characteristic of the X chromosome of the male allows paternity studies of female offspring, even in the absence of the alleged father, constituting the main advantage of microsatellite analysis of the X chromosome compared to its autosomal counterparts. The haplotype of the father's X chromosome will be identical to one of the paternal grandmother's chromosomes, so if at least one allele of each marker analyzed by the grandmother does not match that of the granddaughter, biological paternity can be ruled out. These analyzes have a high probability of exclusion. In turn, in those cases in which the grandmother is also unavailable, her genotype can be reconstructed through the study of the siblings of the alleged father (Szibor et al, 2007 Forensic Sci. Int: Genet. 1: 93-97 ; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74). In a general way, it can be affirmed that the study of STRs of the sibling X chromosome reveals much of the maternal genotype (Szibor et al., 2003 Int. Congr. Ser. 1239: 815-820). Therefore, the analysis of the X chromosome is also useful in the study of more distant kinships such as the previously mentioned grandmother-granddaughter (Liu et al., 2008 Int. J. Legal Med. 122: 261-265), and even in the study of large family pedigrees provided that in each generation there is at least one female descendant. The power of its analysis in this regard lies in the existence of a loci that, due to its physical proximity and its specific characteristics, constitute haplotypic blocks that are inherited together and remain stable throughout the generations (Szibor et al., 2003 Int. Congr Ser. 1239: 815-820). -
Por otro lado, el análisis de STRs del cromosoma X es de gran interés en el estudio de presuntas hermanas o medio-hermanas por parte de padre. Estas deberán compartir un alelo de cada marcador del cromosoma X estudiado, que provienen del padre (Zarrabeitia et al., 2002 Forensic Sci. Int. 129: 85- 89; Liu et al. Int. J. Legal Med. 122:261- 265; Zarrabeitia et al., 2006 Int. J. Legal Med. 120:147- 150; Gomes et al., 2008 Int. J. Legal Med. 123 (2):143- 149; Zarrabeitia et al., 2007 Int. J. Legal Med. 121 : 433- 437; Becker et al., 2008 Forensic Sci. Int. Genet. 2(l):69-74). On the other hand, the analysis of STRs of the X chromosome is of great interest in the study of presumed sisters or half-sisters by the father. These should share an allele of each marker of the X chromosome studied, which come from the father (Zarrabeitia et al., 2002 Forensic Sci. Int. 129: 85-89; Liu et al. Int. J. Legal Med. 122: 261- 265; Zarrabeitia et al., 2006 Int. J. Legal Med. 120: 147-150; Gomes et al., 2008 Int. J. Legal Med. 123 (2): 143-149; Zarrabeitia et al., 2007 Int J. Legal Med. 121: 433-437; Becker et al., 2008 Forensic Sci. Int. Genet. 2 (l): 69-74).
En el caso particular de incestos padre-hija, los microsatélites del cromosoma X complementan el análisis de STR autosómicos, ya que si la hija se queda embarazada, en su descendencia femenina no existirá ningún alelo distinto a los presentes en dicha progenitora. Su utilidad destacaría en cuanto a excluir un supuesto incesto. Mientras que debido a las limitaciones de inclusión de los STRs del cromosoma X, es necesario considerar que el haplotipo del cromosoma X puede ser compartido por otros miembros de la misma familia (Szibor et al., 2007 Forensic Sci. Int: Genet. 1 :93-97; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74). In the particular case of father-daughter incests, the microsatellites of the X chromosome complement the autosomal STR analysis, since if the daughter becomes pregnant, in her female offspring there will be no allele other than those present in said parent. Its usefulness would stand out in terms of excluding a supposed incest. While due to the limitations of inclusion of the X chromosome STRs, it is necessary to consider that the X chromosome haplotype can be shared by other members of the same family (Szibor et al., 2007 Forensic Sci. Int: Genet. 1: 93-97; Szibor et al., 2003 Int. J. Legal Med. 1 17: 67-74).
Aplicación del cromosoma Xen identificación. Application of the X chromosome in identification.
En lo que se refiere al análisis de indicios biológicos, los estudios de microsatélites del Cromosoma X, resultan especialmente útiles en la identificación de un perfil femenino en una evidencia que contenga una mezcla de ADN masculino y femenino. En este caso, los alelos de la muestra femenina pueden ser completamente enmascarados por los alelos de la muestra masculina, solamente si la mujer es homocigótica y coincidente en todos los loci con el hombre, suceso muy poco probable. Por lo que, dichos análisis resultan de utilidad en la resolución de casos criminales en los que pongamos como ejemplo, sea necesaria la demostración de la presencia de células epiteliales ó vaginales femeninas, en el cuerpo del supuesto agresor o en objetos con los que esté haya estado en contacto.  With regard to the analysis of biological evidence, X-chromosome microsatellite studies are especially useful in identifying a female profile in evidence that contains a mixture of male and female DNA. In this case, the alleles of the female sample can be completely masked by the alleles of the male sample, only if the woman is homozygous and coincides in all loci with the man, very unlikely event. Therefore, these analyzes are useful in solving criminal cases in which we give as an example, it is necessary to demonstrate the presence of female epithelial or vaginal cells, in the body of the alleged aggressor or in objects with which there are been in touch
Creciente desarrollo de reacciones para el análisis de STRs del cromosoma X. Increasing development of reactions for the analysis of X chromosome STRs.
Debido a las aplicaciones descritas en los epígrafes anteriores, el desarrollo de reacciones que permitan el análisis simultáneo de diferentes loci STRs ha suscitado un interés creciente. La primera de estas reacciones fue desarrollada en el año 2002 por el grupo de Zarrabeitia et al., y está constituida por los STRs (DXS7423 y DXS8377) (Zarrabeitia et al., 2002 Int. J. Legal Med. 1 16:368- 371). En ese mismo año, el mismo grupo de investigación desarrolló una segunda reacción multiplex formada por los microsatélites (HPRTB, DXS 101 , ARA, DXS7423 y DXS8377) (Zarrabeitia et al., 2002 Forensic Sci. Int. 129: 85- 89). Desde ese momento, se ha descrito un número creciente de STRs del cromosoma X con utilidad en Genética Forense entre otras áreas (tabla 1). Paralelamente, se han ido desarrollado numerosas reacciones multiplex para el análisis simultáneo de varios de estos loci del cromosoma X, tal y como se recoge en la tabla 2. Due to the applications described in the previous sections, the development of reactions that allow the simultaneous analysis of different STRs loci has generated a growing interest. The first of these reactions was developed in 2002 by the group of Zarrabeitia et al., And is constituted by STRs (DXS7423 and DXS8377) (Zarrabeitia et al., 2002 Int. J. Legal Med. 1 16: 368- 371). In the same year, the same research group developed a second multiplex reaction formed by microsatellites (HPRTB, DXS 101, ARA, DXS7423 and DXS8377) (Zarrabeitia et al., 2002 Forensic Sci. Int. 129: 85-89). Since that time, an increasing number of X chromosome STRs with utility in Forensic Genetics among other areas has been described (table 1). In parallel, numerous multiplex reactions have been developed for the simultaneous analysis of several of these X chromosome loci, as shown in Table 2.
Tabla 1 . Características principales de los loci STRs del cromosoma X utilizados en GenéticaTable 1 . Main characteristics of the X chromosome STRs loci used in genetics
Forense hasta la fecha. Forensic to date.
Figure imgf000007_0001
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Figure imgf000007_0001
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Figure imgf000008_0001
Figure imgf000009_0001
Figure imgf000010_0001
- -
Figure imgf000011_0002
Figure imgf000008_0001
Figure imgf000009_0001
Figure imgf000010_0001
- -
Figure imgf000011_0002
Tabla 2. Principales reacciones multiplex para el análisis de loci del cromosoma X. Las reacciones señaladas en sombreado gris corresponden a aquellas explotadas comercialmente.  Table 2. Main multiplex reactions for the analysis of the X chromosome loci. The reactions indicated in gray shading correspond to those commercially exploited.
Figure imgf000011_0001
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Figure imgf000011_0001
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Figure imgf000012_0001
Figure imgf000012_0001
* entype Argus X-UL kit. User's manual. Biotype (2004). * Entype Argus X-UL kit. User's manual. Biotype (2004).
Problema del análisis de ADN degradado. Problem of degraded DNA analysis.
Uno de los principales inconvenientes de las reacciones desarrolladas hasta la fecha es el limitado número de STRs que se pueden analizar a partir de extractos de ADN altamente degradados, lo que disminuye su rendimiento tanto en diagnóstico de parentesco como en la resolución de identificaciones.  One of the main drawbacks of the reactions developed to date is the limited number of STRs that can be analyzed from highly degraded DNA extracts, which decreases their performance both in kinship diagnosis and in the resolution of identifications.
La degradación del ADN se caracteriza por una fragmentación general del material genético, donde los fragmentos de ADN pueden rondar los 240 pb precisando estas reacciones fragmentos de mayor tamaño (tabla 2), para el análisis de todos los loci STRs que incluyen los kits comerciales. El ADN altamente degradado es una característica de la mayoría de las muestras que se analizan en los laboratorios de genética criminalística, en diagnósticos de parentesco y también de aquellas obtenidas a partir de muestras biológicas contenidas en parafina en los centros sanitarios. En estos casos se produce la ausencia de resultados o - - The degradation of DNA is characterized by a general fragmentation of the genetic material, where DNA fragments can be around 240 bp, and these reactions require larger fragments (table 2), for the analysis of all STRs loci that include commercial kits. Highly degraded DNA is a characteristic of most of the samples that are analyzed in criminal genetic laboratories, in kinship diagnoses and also of those obtained from biological samples contained in paraffin in health centers. In these cases the absence of results or - -
incluso la obtención de resultados erróneos, con las graves repercusiones judiciales y/o personales que ello puede conllevar. even obtaining erroneous results, with the serious judicial and / or personal repercussions that this may entail.
Con el fin de corregir este inconveniente se han realizado numerosos esfuerzos para desarrollar reacciones que posibiliten la obtención de perfiles genéticos suficientemente discriminativos a partir de extractos de ADN altamente degradado (Lygo et al., 1994 Int. J. Legal Med. 107:77-89; Whitaker 30 et al., 1995 BioTechniques 18(4):670-677). In order to correct this problem, numerous efforts have been made to develop reactions that allow obtaining sufficiently discriminative genetic profiles from highly degraded DNA extracts (Lygo et al., 1994 Int. J. Legal Med. 107: 77- 89; Whitaker 30 et al., 1995 BioTechniques 18 (4): 670-677).
En este contexto han surgido numerosas solicitudes de patentes, relacionadas con la obtención de perfiles genéticos mediante el análisis simultáneo de varios loci STRs (US6090558, US6479235, ES2273367, US6479235, US2003/0186272). Sin embargo, hasta la fecha la mayoría de estas iniciativas se han limitado al análisis de STR localizados en los cromosomas autosómicos, habiéndose desarrollado un número netamente inferior de reacciones que permitan analizar STRs del cromosoma X a partir de extractos de ADN altamente degradados. Concretamente, en lo referente a loci del cromosoma X cabe destacar las dos reacciones multiplex desarrolladas por Asamura et al., 2006 Int. J. Legal Med. 120: 174- 181 (tabla 3Reacciones a y b). La primera de estas reacciones ha sido específicamente diseñada para analizar los loci DXS7423, GATA31E08, DXS6789 y DXS 101, a partir de fragmentos que superen las 169 pb pares de bases. Mientras que la segunda reacción permite el análisis de los loci DXS7133, DXS7424, GATA165B12 y DXS8378, incluso a partir de fragmentos que superen las 1 1 1 pb. In this context, numerous patent applications have arisen, related to obtaining genetic profiles through the simultaneous analysis of several STR loci (US6090558, US6479235, ES2273367, US6479235, US2003 / 0186272). However, to date, most of these initiatives have been limited to the analysis of STR located in autosomal chromosomes, having developed a clearly lower number of reactions that allow the analysis of STRs of the X chromosome from highly degraded DNA extracts. Specifically, with respect to the X chromosome loci, the two multiplex reactions developed by Asamura et al., 2006 Int. J. Legal Med. 120: 174-181 (table 3Reactions a and b) stand out. The first of these reactions has been specifically designed to analyze the DXS7423, GATA31E08, DXS6789 and DXS 101 loci, from fragments that exceed 169 bp base pairs. While the second reaction allows the analysis of loci DXS7133, DXS7424, GATA165B12 and DXS8378, even from fragments that exceed 1 1 1 bp.
Así mismo, las dos reacciones desarrolladas por Diegoli et Coble., 2010 Forensic Sci. Int. Genet. 5(5)415- 421 (tabla 3 reacciones c y d), permiten por un lado el análisis de los loci GATA165B12, DXS7130, GATA31E08, DXS6789, DXS101, DXS7424 y DXS9902; y por otro, de los loci DXS7423, DXS6795, DXS8378, DXS6803 y GATA172D05, HPRTB, DXS7132, DXS 10147, DXS9902, ambas a partir de fragmentos de ADN superiores a 191 pb en tamaño. Asimismo en la tabla 4 se observa un estudio comparativo de los tamaños en pares de bases de los amplicones correspondientes a loci miniSTRs del cromosoma X en las principales reacciones multiplex del estado de la técnica. Los miniSTRs son los productos resultantes del rediseño de cebadores, los cuales se unen a regiones lo más cercanas posible a la estructura del STR, con el propósito de obtener amplicones de reducido tamaño. Se incluye también los tamaños correspondientes a la reacción decaplex desarrollada por Gusmao et. al., - - Likewise, the two reactions developed by Diegoli et Coble., 2010 Forensic Sci. Int. Genet. 5 (5) 415- 421 (table 3 reactions c and d), allow on the one hand the analysis of loci GATA165B12, DXS7130, GATA31E08, DXS6789, DXS101, DXS7424 and DXS9902; and on the other, of the DXS7423, DXS6795, DXS8378, DXS6803 and GATA172D05, HPRTB, DXS7132, DXS 10147, DXS9902 loci, both from DNA fragments larger than 191 bp in size. Table 4 also shows a comparative study of the base pair sizes of the amplicons corresponding to miniSTR loci of the X chromosome in the main multiplex reactions of the prior art. The miniSTRs are the products resulting from the redesign of primers, which join regions as close as possible to the structure of the STR, with the purpose of obtaining amplicons of reduced size. The sizes corresponding to the decaplex reaction developed by Gusmao et. to the., - -
2009 Int. J. Legal Med. 123 (3): 227- 234 ya que si bien no incluye únicamente miniSTRs, posibilita el análisis de los loci STRs DXS8378, DXS9898, DXS7133, GATA172D05, DXS7423, DXS7132 y DXS9902, a partir de fragmentos de un tamaño superior a las 213 pb. Tabla 3. Reacciones multiplex expresamente diseñadas para el análisis de loci del cromosoma X en formato miniSTR. 2009 Int. J. Legal Med. 123 (3): 227-234 since although it does not include only miniSTRs, it allows the analysis of the STRX loci DXS8378, DXS9898, DXS7133, GATA172D05, DXS7423, DXS7132 and DXS9902, from fragments of a size greater than 213 bp. Table 3. Multiplex reactions expressly designed for the analysis of X chromosome loci in miniSTR format.
Figure imgf000014_0002
Figure imgf000014_0002
Tabla 4 Relación de los principales loci miniSTRs del estado de la técnica. Se detalla el tamaño en pares de bases de cada amplicón al ser analizado por las principales reacciones multiplex. Table 4 List of the main miniSTR loci of the prior art. The base pair size of each amplicon is detailed when analyzed by the main multiplex reactions.
Figure imgf000014_0001
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Figure imgf000014_0001
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Figure imgf000015_0001
Figure imgf000015_0001
Así pues, no existen en la actualidad reacciones multiplex que proporcionen la posibilidad de analizar la totalidad de los loci del cromosoma X descritos hasta la fecha a partir de extractos de ADN que no superen las 150-200 pb, tamaño habitualmente considerado para loci miniSTRs, ni tampoco las 240 pb, tamaño característico en el ADN altamente degradado al ser el correspondiente a una unidad nucleosómica.  Thus, there are currently no multiplex reactions that provide the possibility to analyze all of the X chromosome loci described to date from DNA extracts that do not exceed 150-200 bp, size usually considered for miniSTR loci, nor the 240 bp, characteristic size in highly degraded DNA as it corresponds to a nucleosomal unit.
Por lo tanto, a pesar de los hitos detallados anteriormente, existe en el estado de la técnica la necesidad de desarrollar métodos para obtener perfiles genéticos, alternativos a los ya existentes, que superen los inconvenientes antes citados y que permitan obtener perfiles genéticos fiables de loci localizados en el cromosoma X, incluso a partir de extractos de ADN altamente degradados. Therefore, despite the milestones detailed above, there is a need in the prior art for developing methods to obtain genetic profiles, alternative to those already existing, that overcome the aforementioned drawbacks and allow obtaining reliable genetic loci profiles located on the X chromosome, even from highly degraded DNA extracts.
COMPENDIO DE LA INVENCIÓN - - SUMMARY OF THE INVENTION - -
En la actualidad existen numerosas empresas que comercializan kits para la elaboración de perfiles genéticos, pero ninguno de ellos, ni su combinación, permite analizar los loci STRs del cromosoma X a partir de fragmentos de ADN de 240 pb. Para solventar este problema los inventores han diseñado unas parejas de cebadores dirigidas a amplificar los loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079 a partir de fragmentos de ADN que superen las 220 pb. Además proporciona la característica técnica adicional de que, si se desea, pueden emplearse simultáneamente en combinaciones de 4 o más parejas de cebadores en una reacción de amplificación multiplex para obtener un perfil genético compuesto de hasta 8 loci STRs. Esta característica de las parejas de cebadores diseñadas en la invención permite su empleo en casos de determinación de parentesco en los que las muestras de uno de los progenitores no están disponibles para el análisis, aún cuando las muestras disponibles presenten un grado elevado de degradación. Así, un aspecto principal de la invención se relaciona con un método para obtener el perfil genético de un individuo que comprende el análisis, en un extracto de ADN procedente de dicho individuo, mediante una reacción de amplificación multiplex, de al menos 4 loci STRs del grupo formado por los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079 en donde At present there are numerous companies that sell kits for the elaboration of genetic profiles, but none of them, nor their combination, allows to analyze the X-chromosome STRs loci from DNA fragments of 240 bp. To solve this problem, the inventors have designed pairs of primers aimed at amplifying the DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci from DNA fragments exceeding 220 bp. It also provides the additional technical feature that, if desired, they can be used simultaneously in combinations of 4 or more primer pairs in a multiplex amplification reaction to obtain a genetic profile composed of up to 8 STRs loci. This characteristic of the pairs of primers designed in the invention allows their use in cases of kinship determination in which the samples of one of the parents are not available for analysis, even if the available samples have a high degree of degradation. Thus, a main aspect of the invention relates to a method for obtaining the genetic profile of an individual comprising the analysis, in a DNA extract from said individual, by means of a multiplex amplification reaction of at least 4 STRs loci of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 where
a) al menos uno de los 4 loci STRs se selecciona del grupo formado por los loci a) at least one of the 4 STR loci is selected from the group formed by the loci
DXS6799, DXS 10074, DXS6789 y DXS6809; y DXS6799, DXS 10074, DXS6789 and DXS6809; Y
b) al menos dos de los 4 loci STRs se selecciona del grupo formado por los loci DXS7132, DXS6801 , DXS 10075 y DXS 10079.  b) at least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
Por otro lado, la invención proporciona un kit que comprende parejas de cebadores específicas para amplificar al menos 4 loci STRs seleccionados del grupo formado por los loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS10079, en donde a) al menos 1 de los 4 loci STRs se selecciona del grupo formado por los loci DXS6799, DXS 10074, DXS6789 y DXS6809; y  On the other hand, the invention provides a kit comprising pairs of specific primers to amplify at least 4 STR loci selected from the group formed by loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS10079, wherein a) at least 1 of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS 10074, DXS6789 and DXS6809 loci; Y
b) al menos dos de los 4 loci STRs se selecciona del grupo formado por los loci b) at least two of the 4 STR loci are selected from the group formed by the loci
DXS7132, DXS6801, DXS 10075 y DXS 10079 - - DXS7132, DXS6801, DXS 10075 and DXS 10079 - -
Asimismo, la invención se relaciona con un conjunto de parejas de cebadores que comprende, al menos, 4 parejas de cebadores dirigidas a amplificar 4 loci STRs del grupo formado por los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079 en donde a) al menos uno de los 4 loci STRs se selecciona del grupo formado por los loci DXS6799, DXS 10074, DXS6789 y DXS6809; y Also, the invention relates to a set of primer pairs comprising at least 4 primer pairs aimed at amplifying 4 STR loci of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 wherein a) at least one of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS 10074, DXS6789 and DXS6809 loci; Y
b) al menos dos de los 4 loci STRs se selecciona del grupo formado por los loci DXS7132, DXS6801 , DXS 10075 y DXS 10079.  b) at least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
Por otra parte se contempla el uso del conjunto de parejas de cebadores de la invención para obtener el perfil genético de un individuo, para determinar relaciones de parentesco entre individuos o para identificar restos humanos, On the other hand, the use of the set of primer pairs of the invention is contemplated to obtain the genetic profile of an individual, to determine kinship relationships between individuals or to identify human remains,
Finalmente, en otro aspecto, la invención se relaciona con una pareja de cebadores seleccionada del grupo que consiste en las siguientes parejas de oligonucleótidos - SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799, Finally, in another aspect, the invention relates to a pair of primers selected from the group consisting of the following oligonucleotide pairs - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 1 1 y SEQ ID NO: 12 para el locus DXS6801 , - SEQ ID NO: 1 1 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO 14 y/o SEQ ID NO: 15 para el locus DXS10075, y - SEQ ID NO: 13 and / or SEQ ID NO 14 and / or SEQ ID NO: 15 for locus DXS10075, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079. - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus.
BREVE DESCRIPCIÓN DE LAS FIGURAS BRIEF DESCRIPTION OF THE FIGURES
La Figura 1 corresponde a un gráfico llamado electroferograma que muestra el perfil genético de un individuo para los STRs analizados mediante el conjunto de cebadores de la invención empleando un analizador automático de secuencias AB310 Genetic Analyzer (Applied Biosystems®). En la Figura se pueden observar 4 paneles, cada uno correspondiente a aquellas parejas de cebadores marcadas con el mismo locus fluorescente. En cada panel se muestra la intensidad de la señal detectada en Relative Fluorescence Units (RFU, unidad relativa de fluorescencia.) en el eje Y; el eje X corresponde al tamaño en pares de bases. Así, - - Figure 1 corresponds to a graph called electropherogram showing the genetic profile of an individual for the STRs analyzed by the set of primers of the invention using an automatic AB310 Genetic Analyzer (Applied Biosystems ® ) sequence analyzer. In the Figure 4 panels can be observed, each corresponding to those pairs of primers marked with the same fluorescent locus. Each panel shows the intensity of the signal detected in the Relative Fluorescence Units (RFU, relative fluorescence unit) on the Y axis; The X axis corresponds to the size in base pairs. So, - -
el primer panel corresponde a los resultados obtenidos para los productos de STRs amplificados con cebadores marcados con 6-FAM™ (dirigidos a los loci DXS6799 y DXS 10074, el segundo panel a los marcados con VIC™(DXS7132 y DXS6801 ), el tercero a NED™ (loci DXS6789 y DXS6809) y en el cuarto panel se muestran los resultados para los loci STRs marcados con el fluorocromo PET® (DXS 10075 y DXS 10079). Las barras situadas en la parte superior de cada panel corresponden al nombre de los loci. Los rectángulos situados bajos los picos del electroferograma muestran el nombre del alelo, indicado por un número. La Figura 2 es una representación gráfica que muestra el diseño del conjunto de parejas de cebadores denominada miniX. Las cajas representan los tamaños de amplificado para cada locus. Los loci marcados con diferente color se presentan en diferentes escalas de grises. Los respectivos mareajes se señalan en la parte derecha de la figura. La Figura 3 es una comparación del rendimiento obtenido mediante miniX y Decaplex, en el análisis de los loci compartidos por ambas reacciones, a partir de 24 muestras de parafina. the first panel corresponds to the results obtained for the products of STRs amplified with primers marked with 6-FAM ™ (directed to the loci DXS6799 and DXS 10074, the second panel to those marked with VIC ™ (DXS7132 and DXS6801), the third to NED ™ (loci DXS6789 and DXS6809) and fourth panel results for loci STRs labeled with the fluorochrome PET ® (DXS 10075 and DXS 10079) are shown. the bars at the top of each panel correspond to the name of loci The rectangles located under the electropherogram peaks show the name of the allele, indicated by a number, Figure 2 is a graphic representation showing the design of the set of primer pairs called miniX.The boxes represent the amplified sizes for each locus Loci marked with different color are presented in different gray scales The respective tides are indicated in the right part of the figure Figure 3 is a comparison of the The method obtained by miniX and Decaplex, in the analysis of the loci shared by both reactions, from 24 paraffin samples.
La Figura 4 es una comparación del rendimiento obtenido mediante miniX y Sextaplex, en el análisis de los loci compartidos por ambas reacciones, a partir de 24 muestras de parafina. Figure 4 is a comparison of the yield obtained by miniX and Sextaplex, in the analysis of the loci shared by both reactions, from 24 paraffin samples.
DESCRIPCIÓN DETALLADA DE LA INVENCIÓN DETAILED DESCRIPTION OF THE INVENTION
En la actualidad existen numerosas empresas que comercializan kits para la elaboración de perfiles genéticos, pero ninguno de ellos, ni su combinación permite analizar los loci STRs del cromosoma X hasta la fecha a partir de fragmentos de ADN de 240 pb. Para solventar este problema los inventores han diseñado unas parejas de cebadores dirigidas a amplificar los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079 a partir de fragmentos de ADN que superen las 220 pb, con la característica técnica adicional de que, si se desea, pueden emplearse simultáneamente en combinaciones de 4 o más parejas de cebadores en una reacción de amplificación multiplex para obtener un perfil genético compuesto de hasta 8 loci STRs. - - At present there are numerous companies that sell kits for the elaboration of genetic profiles, but none of them, nor their combination allows to analyze the X-chromosome STRs loci to date from 240 bp DNA fragments. To solve this problem, the inventors have designed a pair of primers aimed at amplifying the DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci from DNA fragments exceeding 220 bp, with the characteristic Additional technique that, if desired, can be used simultaneously in combinations of 4 or more primer pairs in a multiplex amplification reaction to obtain a genetic profile composed of up to 8 STRs loci. - -
Dicha característica permite la aplicación de esta invención en la resolución de casos de paternidad complejos a partir de muestras de ADN altamente degradadas con mayor eficacia que los kits comerciales desarrollados hasta la fecha para el análisis de los loci del cromosoma X mencionados. Said feature allows the application of this invention in the resolution of complex paternity cases from highly degraded DNA samples more effectively than commercial kits developed to date for the analysis of the aforementioned X chromosome loci.
Así, en base a estas parejas de cebadores, se han desarrollado los distintos aspectos inventivos que forman parte de la presente invención y que serán descritos en detalle a continuación. Previamente a la descripción de dichos aspectos inventivos, se incluye un listado de definiciones donde se explica el significado de los términos empleados en el contexto de la presente invención para ayudar en la comprensión de la misma. Thus, based on these pairs of primers, the different inventive aspects that are part of the present invention and which will be described in detail below have been developed. Prior to the description of said inventive aspects, a list of definitions is included explaining the meaning of the terms used in the context of the present invention to aid in the understanding thereof.
Definiciones Definitions
Perfil Genético Genetic Profile
En el contexto de la presente invención, los términos "perfil genético" y "huella genética" tienen el mismo significado por lo que pueden emplearse indistintamente a lo largo de la descripción. El "perfil genético" es un conjunto de secuencias de bases características del material genético que permiten diferenciar a un individuo de otro. Loci STRs In the context of the present invention, the terms "genetic profile" and "genetic fingerprint" have the same meaning and can therefore be used interchangeably throughout the description. The "genetic profile" is a set of sequences of characteristic bases of the genetic material that allow differentiating an individual from another. STR loci
En la presente invención, el perfil genético se obtiene a partir del análisis de secuencias de bases cortas repetidas en tándem o STRs (del inglés Short Tándem Repeats) que se caracterizan por su alta variabilidad entre individuos. Así, en la presente invención se entiende por "secuencias STRs" o "loci STRs" aquellas secuencias del ADN, también llamadas microsatélites, que contienen repeticiones de 4 pb (Butler JM, Biotechniques. 2007).  In the present invention, the genetic profile is obtained from the analysis of sequences of short bases repeated in tandem or STRs (of English Short Tandem Repeats) that are characterized by their high variability among individuals. Thus, "STRs sequences" or "STRs loci" means those DNA sequences, also called microsatellites, that contain 4 bp repeats (Butler JM, Biotechniques. 2007).
El análisis de los loci STRs en el genoma presenta múltiples aplicaciones que incluyen, aunque no se limitan a, obtención de perfiles genéticos, diagnósticos de parentesco, determinación del origen de una muestra o tejido, identificación de cadáveres, estudios de genética de poblaciones, pruebas de zigosidad en mellizos, seguimiento de transplantes de médula ósea, evaluación de la trazabilidad de muestras biológicas de origen humano, identificación de mezclas presentes en una muestra y determinación del número de contribuyentes de origen humano a una mezcla y su aportación relativa a la mezcla. - - The analysis of the STRs loci in the genome presents multiple applications that include, but are not limited to, obtaining genetic profiles, kinship diagnoses, determining the origin of a sample or tissue, identification of cadavers, population genetics studies, tests of zygosity in twins, monitoring of bone marrow transplants, evaluation of the traceability of biological samples of human origin, identification of mixtures present in a sample and determination of the number of contributors of human origin to a mixture and their contribution relative to the mixture. - -
PCRPCR
PCR corresponde a las siglas de reacción en cadena de la polimerasa mediante la cual se pueden obtener millones de copias de las regiones de ADN deseadas. Se caracteriza por el empleo de parejas de cebadores que acotan la región de la que se realizarán millones de copias, lo que también se conoce como "amplificar ADN" durante la PCR. La PCR está compuesta por un número determinado de ciclos, compuestos a su vez por tres fases en las que las hebras de ADN se separan, se unen los cebadores y se elongan las nuevas hebras de ADN. En cada ciclo, si la eficiencia de la reacción es del 100% se produce un crecimiento exponencial de los fragmentos de ADN objeto de la amplificación. PCR corresponds to the polymerase chain reaction acronym whereby millions of copies of the desired DNA regions can be obtained. It is characterized by the use of pairs of primers that delimit the region from which millions of copies will be made, which is also known as "amplifying DNA" during PCR. The PCR is composed of a certain number of cycles, in turn composed of three phases in which the DNA strands are separated, the primers are joined and the new DNA strands are elongated. In each cycle, if the reaction efficiency is 100%, exponential growth of the DNA fragments subject to amplification occurs.
Reacción de amplificación multiplex Multiplex amplification reaction
En la presente invención se entiende por "Reacción de amplificación multiplex" a la reacción PCR en la cual se amplifica más de una secuencia de ADN en una misma reacción, mediante el empleo de dos o más parejas de cebadores en único tubo junto con el resto de los reactivos de la reacción con el fin de amplificar simultáneamente múltiples secuencias de ADN.  In the present invention, "multiplex amplification reaction" is understood as the PCR reaction in which more than one DNA sequence is amplified in the same reaction, by using two or more pairs of primers in a single tube together with the rest. of the reaction reagents in order to simultaneously amplify multiple DNA sequences.
Oligonucleó tido Oligonucleotide
El término "oligonucleótido" hace referencia a la secuencia de bases de nucleótidos unidos por enlaces fosfo-diéster, habirualmente no mayor de 50 nucleótidos.  The term "oligonucleotide" refers to the sequence of nucleotide bases linked by phospho-diester bonds, usually not greater than 50 nucleotides.
Cebador Primer
En la presente invención se entiende por "cebador" o "primer" u "oligonucleótido" ("oligo") a la secuencia de nucleótidos a partir de la cual la ADN polimerasa inicia la síntesis de una molécula nueva de ADN. Los cebadores son secuencias nucleotídicas cortas, aproximadamente de 15-24 nucleótidos de longitud que se pueden alinear con una hebra de ADN diana gracias a la complementariedad de bases para formar un híbrido entre el cebador y la hebra diana de ADN. Después, el enzima ADN polimerasa puede extender el cebador a lo largo de la hebra diana de ADN. Los métodos para preparar y usar cebadores se describen, por ejemplo en Sambrook et al., 2001 y Ausubel et al., 1999.  In the present invention, "primer" or "first" or "oligonucleotide" ("oligo") is understood as the nucleotide sequence from which DNA polymerase initiates the synthesis of a new DNA molecule. The primers are short nucleotide sequences, approximately 15-24 nucleotides in length that can be aligned with a strand of target DNA thanks to the complementarity of bases to form a hybrid between the primer and the target strand of DNA. Then, the DNA polymerase enzyme can extend the primer along the DNA strand. Methods for preparing and using primers are described, for example in Sambrook et al., 2001 and Ausubel et al., 1999.
Pareja de cebadores - - Pair of primers - -
En el contexto de la presente invención se entiende por "pareja de cebadores" o "primer pair", al conjunto de dos cebadores que, empleados en una misma reacción de amplificación o PCR, permiten obtener múltiples copias de una secuencia diana de ADN. Cada uno de los cebadores híbrida con la secuencia diana, de manera que se amplifica la secuencia de nucleótidos acotada mediante cada pareja de cebadores. La extensión de los cebadores durante los ciclos de PCR determina la multiplicación exponencial 2N de la secuencia de nucleótidos acotada por los cebadores, siendo N el número de ciclos de la reacción PCR. In the context of the present invention, "primer pair" or "first pair" is understood as the set of two primers which, when used in the same amplification or PCR reaction, allow multiple copies of a DNA target sequence to be obtained. Each of the primers hybridizes with the target sequence, so that the bounded nucleotide sequence is amplified by each pair of primers. The extent of the primers during the PCR cycles determines the 2 N exponential multiplication of the nucleotide sequence bounded by the primers, N being the number of cycles of the PCR reaction.
Muestra biológica Biological sample
En el contexto de la presente invención, se entiende por "muestra biológica" cualquier materia que contenga un ácido nucleico, por ejemplo, ADN. En la presente invención se entiende por "ADN" o "ADN genómico" al material genético de los organismos vivos que controla la herencia y se localiza en el núcleo de las células. Extracto de ADN In the context of the present invention, "biological sample" means any matter that contains a nucleic acid, for example, DNA. In the present invention, "DNA" or "genomic DNA" is understood as the genetic material of living organisms that controls inheritance and is located in the nucleus of cells. DNA Extract
En el contexto de la presente invención se entiende "extracto de ADN", cuando tras someter la muestra biológica a un procedimiento de extracción, separación, purificación o clonación de ADN, entre otros, se obtiene como resultado ya sea en seco, en solución, unido o no a otras moléculas, adherido o no a diversas sustancias o lechos, materia en la que el ADN se encuentra en mayor proporción relativa respecto al resto de moléculas presentes, en comparación con la muestra biológica de partida.  In the context of the present invention, "DNA extract" is understood when, after subjecting the biological sample to a method of extraction, separation, purification or cloning of DNA, among others, it is obtained as a result either dry, in solution, bound or not to other molecules, adhered or not to various substances or beds, matter in which the DNA is in a greater relative proportion with respect to the rest of the molecules present, compared to the biological starting sample.
Así "extracto de ADN" se refiere al ADN extraído de cualquier muestra biológica que contenga ADN humano, ya sea procedente de un individuo vivo o muerto, feto, órganos, tejidos ó células. Thus "DNA extract" refers to DNA extracted from any biological sample that contains human DNA, whether from a living or dead individual, fetus, organs, tissues or cells.
Individuo Individual
El término "individuo" se refiere a ser humano de cualquier edad o raza, que en el contexto de la presente invención puede estar viva o muerta.  The term "individual" refers to a human being of any age or race, who in the context of the present invention may be alive or dead.
Cebadores de la invención - - Primers of the invention - -
Los inventores han diseñado unas parejas de cebadores, de aquí en adelante, "parejas de cebadores de la invención" o "miniX", que permite obtener el perfil genético de los loci STRs (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079) de un individuo, incluso a partir de muestras de ADN altamente degradadas, y es aplicable incluso al análisis de parentesco complejo. The inventors have designed a pair of primers, henceforth, "pairs of primers of the invention" or "miniX", which allows obtaining the genetic profile of the STRs loci (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 and DXS 10079) of an individual, even from highly degraded DNA samples, and is applicable even to complex kinship analysis.
Así, MiniX se caracteriza por permitir analizar un alto número de loci STR mediante amplificados de reducido tamaño. De modo que, ha sido específicamente diseñada para posibilitar la amplificación de 8 loci STRs, a partir de fragmentos de ADN que superen las 220 pb. Destaca por ser el único sistema disponible en la actualidad que permite analizar la totalidad de los loci STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079, en una única reacción multiplex. Además, incluye amplificados de menor tamaño que los disponibles en el estado de la técnica en 6 de los 8 loci STRs incluidos. La excepción la constituyen el locus DXS 10074 y el DXS6801 que dan lugar a amplificados 27 y 37 pb mayores que los obtenidos mediante las reacciones desarrolladas por Becker et. al., 2008 Forensic. Sci. Int. Genet. 2(1): 69-74 y Castañeda et al., 2012 J. Forensic Sci. 57(1): 192-195, respectivamente (Tabla 10). Thus, MiniX is characterized by allowing a high number of STR loci to be analyzed by small amplified amplifiers. So, it has been specifically designed to enable the amplification of 8 STRs loci, from DNA fragments that exceed 220 bp. It stands out for being the only system currently available that allows analyzing all the STRX DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci, in a single multiplex reaction. In addition, it includes amplifiers smaller than those available in the state of the art in 6 of the 8 STR loci included. The exception is the DXS 10074 locus and the DXS6801 that give rise to amplitudes 27 and 37 bp greater than those obtained by the reactions developed by Becker et. al., 2008 Forensic. Sci. Int. Genet. 2 (1): 69-74 and Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195, respectively (Table 10).
Las parejas de cebadores han sido diseñadas de manera que su aplicación permite obtener el perfil genético de un individuo que comprende la combinación de al menos 4 hasta 8 loci STR. Además, la parejas de cebadores diseñadas presentan la característica técnica adicional de que, si se desea, pueden emplearse simultáneamente en combinaciones de 4 o hasta 8 parejas de cebadores en una reacción de amplificación multiplex para obtener un perfil genético compuesto de 4 o más loci STRs hasta un total de 8 loci STRs cuyo análisis de elevado interés en Genética Forense y de Genética de Poblaciones, sin estar limitado dicho interés a estas áreas. The primer pairs have been designed so that their application allows obtaining the genetic profile of an individual that comprises the combination of at least 4 to 8 STR loci. In addition, the designed primer pairs have the additional technical characteristic that, if desired, they can be used simultaneously in combinations of 4 or up to 8 primer pairs in a multiplex amplification reaction to obtain a genetic profile composed of 4 or more STRs loci up to a total of 8 STR loci whose analysis of high interest in Forensic Genetics and Population Genetics, without limiting this interest to these areas.
Los loci STRs analizados en la presente invención así como las parejas de cebadores diseñadas para su identificación se muestran en la Tabla 5. En esta misma tabla se detalla del alelo menor al mayor del STR que será considerado mediante este análisis (columna: alelos) así como el tamaño máximo y mínimo posible para cada STR. En el Ejemplo 1 se detalla el procedimiento seguido en el diseño del conjunto de parejas de cebadores de la invención. - - The STRs loci analyzed in the present invention as well as the pairs of primers designed for identification are shown in Table 5. This same table details the minor to major allele of the STR that will be considered by this analysis (column: alleles) as well. as the maximum and minimum possible size for each STR. Example 1 details the procedure followed in the design of the set of primer pairs of the invention. - -
Tal como se muestra en el Ejemplo 1 , el diseño de las parejas de cebadores de la presente invención se llevó a cabo mediante una búsqueda de las secuencias flanqueantes a cada locus STR. Posteriormente se empleó el programa Perlprimer. Una vez obtenidas las parejas de cebadores, se procedió a realizar una reacción de amplificación de la polimerasa sobre un extracto de ADN empleando dichas parejas de cebadores tras lo cual, se obtuvo el perfil genético del individuo al que pertenecía el extracto de ADN con fiabilidad, precisión y con un poder de discriminación superior a los perfiles genéticos obtenidos por otros métodos a partir de muestras de ADN altamente degradadas, tal y como se ilustra en el ejemplo 2. Tabla 5. Resumen de las secuencia de los cebadores en dirección 'a 3 ' diseñados para la amplificación de cada STR en la combinación denominada como miniX (columna: secuencia 5'- 3 '). La variación (rs945048 A/T) de la secuencia de los cebadores degenerados (degenerate primers) aparece subrayado y la base G añadida a la secuencia aparece en negrita para el locus DXS 10075. As shown in Example 1, the design of the primer pairs of the present invention was carried out by searching the flanking sequences at each STR locus. Subsequently, the Perlprimer program was used. Once the primer pairs were obtained, a polymerase amplification reaction was carried out on a DNA extract using said primer pairs after which, the genetic profile of the individual to whom the DNA extract belonged reliably was obtained, precision and with a discriminating power superior to the genetic profiles obtained by other methods from highly degraded DNA samples, as illustrated in example 2. Table 5. Summary of the sequence of primers in the 'to 3 direction 'designed for the amplification of each STR in the combination called as miniX (column: sequence 5 ' - 3 ' ). The variation (rs945048 A / T) of the degenerate primers sequence is underlined and the G base added to the sequence appears in bold for the DXS 10075 locus.
Figure imgf000023_0001
Figure imgf000023_0001
Así, un aspecto principal de la invención se relaciona con un conjunto de parejas de cebadores, de aquí en adelante "conjunto de parejas de cebadores de la invención", que comprende, al menos, 4 parejas de cebadores dirigidas a amplificar 4 locí STRs del grupo formado por los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079, en donde - - Thus, a main aspect of the invention relates to a set of primer pairs, hereafter "set of primer pairs of the invention", comprising at least 4 primer pairs aimed at amplifying 4 loci STRs of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079, where - -
a) al menos uno de los 4 loci STRs se selecciona del grupo formado por los loci DXS6799, DXS10074, DXS6789 y DXS6809; y a) at least one of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS10074, DXS6789 and DXS6809 loci; Y
b) al menos dos de los 4 loci STRs se selecciona del grupo formado por los loci DXS7132, DXS6801, DXS10075 y DXS10079. En una realización particular, el conjunto de parejas de cebadores de la invención comprende, al menos 5, 6, 7 u 8 parejas de cebadores específicas para los loci STRs del grupo formado por los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079. De forma particular, las parejas de cebadores se seleccionan del grupo que consiste en las siguientes parejas de oligonucleótidos:  b) at least two of the 4 STRs loci are selected from the group consisting of loci DXS7132, DXS6801, DXS10075 and DXS10079. In a particular embodiment, the set of primer pairs of the invention comprises at least 5, 6, 7 or 8 specific primer pairs for the STR loci of the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079. In particular, primer pairs are selected from the group consisting of the following oligonucleotide pairs:
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799, - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 1 1 y SEQ ID NO: 12 para el locus DXS6801,  - SEQ ID NO: 1 1 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO 14 y/o SEQ ID NO: 15 para el locus DXS10075, y - SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079.  - SEQ ID NO: 13 and / or SEQ ID NO 14 and / or SEQ ID NO: 15 for the DXS10075 locus, and - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus.
En otro aspecto, la invención se relaciona con una pareja de cebadores seleccionada del grupo que consiste en las siguientes parejas de oligonucleótidos: In another aspect, the invention relates to a pair of primers selected from the group consisting of the following oligonucleotide pairs:
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799,  - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 1 1 y SEQ ID NO: 12 para el locus DXS6801,  - SEQ ID NO: 1 1 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO: 14 y/o SEQ ID NO 15 para el locus DXS 10075, y - SEQ ID NO: 13 and / or SEQ ID NO: 14 and / or SEQ ID NO 15 for the DXS 10075 locus, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079. - - - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus. - -
Uso de los cebadores de la invención Use of the primers of the invention
Los diferentes usos que tienen los cebadores de la invención, constituyen aspectos adicionales de la presente invención. The different uses that the primers of the invention have, constitute additional aspects of the present invention.
Así, los usos del conjunto de parejas de cebadores de la invención incluyen, sin limitarse a, la obtención de perfiles genéticos, diagnósticos de parentesco, determinación del origen de una muestra o tejido, identificación de cadáveres, estudios de genética de poblaciones, pruebas de zigosidad en mellizos, seguimiento de transplantes de médula ósea, evaluación de la trazabilidad de muestras biológicas de origen humano, identificación de mezclas presentes en una muestra, determinación del número de contribuyentes de origen humano a una mezcla y su aportación relativa a la mezcla. Thus, uses of the set of primer pairs of the invention include, but are not limited to, obtaining genetic profiles, kinship diagnoses, determining the origin of a sample or tissue, identification of cadavers, population genetics studies, evidence of Zygosity in twins, monitoring of bone marrow transplants, evaluation of the traceability of biological samples of human origin, identification of mixtures present in a sample, determination of the number of contributors of human origin to a mixture and their contribution relative to the mixture.
Así, en otro aspecto principal de la invención se contempla el uso del conjunto de parejas de cebadores de la invención para obtener el perfil genético de un individuo, para determinar relaciones de parentesco entre individuos o para identificar restos humanos. Thus, in another main aspect of the invention the use of the set of primer pairs of the invention is contemplated to obtain the genetic profile of an individual, to determine kinship relationships between individuals or to identify human remains.
Método de la invención Tal como se ha explicado anteriormente, la presente invención está basada en el diseño de unas parejas de cebadores que permiten obtener el perfil genético de un individuo basado en una combinación de al menos 4 STRs. Method of the invention As explained above, the present invention is based on the design of a pair of primers that allow obtaining the genetic profile of an individual based on a combination of at least 4 STRs.
Así, otro aspecto principal de la invención se relaciona con un método, de aquí en adelante "método de la invención", para obtener el perfil genético de un individuo que comprende el análisis, en un extracto de ADN procedente de dicho individuo, mediante una reacción de amplificación multiplex, de al menos 4 loci STRs del grupo formado por los loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079, en donde a) al menos uno de los 4 loci STRs se selecciona del grupo formado por los loci DXS6799, DXS 10074, DXS6789 y DXS6809; y Thus, another main aspect of the invention relates to a method, hereinafter "method of the invention", to obtain the genetic profile of an individual comprising the analysis, in a DNA extract from said individual, by means of a multiplex amplification reaction, of at least 4 STRs loci from the group consisting of the DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci, where a) at least one of the 4 STRs loci is selected from group formed by loci DXS6799, DXS 10074, DXS6789 and DXS6809; Y
b) al menos dos de los 4 loci STRs se selecciona del grupo formado por los loci DXS7132, DXS6801, DXS 10075 y DXS 10079. - b) at least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci. -
Adicionalmente, las parejas de cebadores han sido diseñadas de tal manera que es posible emplearlas en el análisis de 4 o más, hasta un total de 8 loci STRs, (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079). Así, mediante el empleo de las parejas de cebadores de la invención, es posible obtener el perfil genético de un individuo formado por 5, 6, 7 u 8 loci de los STRs. Additionally, the primer pairs have been designed in such a way that it is possible to use them in the analysis of 4 or more, up to a total of 8 STRs loci, (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079). Thus, by using the pairs of primers of the invention, it is possible to obtain the genetic profile of an individual formed by 5, 6, 7 or 8 loci of the STRs.
Por lo tanto, en una realización particular del método de la invención, el conjunto de parejas de cebadores dirigido a obtener el perfil genético de un individuo está dirigido al análisis de al menos 5, 6, 7 u 8 loci STRs del grupo formado por los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079. Therefore, in a particular embodiment of the method of the invention, the set of primer pairs aimed at obtaining the genetic profile of an individual is directed to the analysis of at least 5, 6, 7 or 8 STR loci of the group formed by the loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079.
En otra realización todavía más particular, la pareja de cebadores empleada en la reacción de amplificación multiplex específica para cada uno de los loci STR analizados es la pareja de oligonucleótidos mostrada en las secuencias In another even more particular embodiment, the primer pair employed in the multiplex amplification reaction specific to each of the STR loci analyzed is the oligonucleotide pair shown in the sequences.
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799, - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 1 1 y SEQ ID NO: 12 para el locus DXS6801,  - SEQ ID NO: 1 1 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO 14 y/o SEQ ID NO: 15 para el locus DXS10075, y - SEQ ID NO: 13 and / or SEQ ID NO 14 and / or SEQ ID NO: 15 for locus DXS10075, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079. - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus.
La puesta en práctica del método de la invención requiere la obtención de un extracto de ADN que procederá, en última instancia, de una muestra biológica que será tratada de forma adecuada para obtener dicho extracto de ADN. The implementation of the method of the invention requires obtaining a DNA extract that will ultimately come from a biological sample that will be adequately treated to obtain said DNA extract.
Como entiende el experto en la materia, si el método de la invención está dirigido a obtener el perfil genético de un individuo o la relación de parentesco entre individuos, el extracto de ADN procederá del individuo cuyo perfil genético quiere obtenerse, o de los individuos cuya relación de parentesco quiere determinarse. Aunque como se ha mencionado anteriormente, la . - As the person skilled in the art understands, if the method of the invention is directed to obtain the genetic profile of an individual or the relationship between individuals, the DNA extract will come from the individual whose genetic profile is to be obtained, or from the individuals whose kinship relationship wants to be determined. Although as mentioned above, the . -
presente invención está especialmente indicada para resolver aquellas relaciones de parentesco en las que las muestras biológicas de algunos de las personas implicadas no están disponibles. Sin embargo, si el método de la invención está dirigido a la identificación de restos humanos, el extracto de ADN procederá de los restos humanos que se quieren identificar. En la presente invención, el término "restos humanos" incluye cualquier muestra biológica procedente de un ser humano, pudiendo estar dicho resto humano conservado en formol, congelado, desecado, fijado en parafína, en estado de descomposición, degradación y/o putrefacción, entre otros. The present invention is especially indicated to resolve those kinship relationships in which the biological samples of some of the people involved are not available. However, if the method of the invention is directed to the identification of human remains, the DNA extract will come from the human remains that are to be identified. In the present invention, the term "human remains" includes any biological sample from a human being, said human residue being able to be preserved in formol, frozen, dried, fixed in paraffin, in a state of decomposition, degradation and / or rot, between others.
Ejemplos de muestras de las que se puede obtener ADN son, sin limitar a, fluidos biológicos (sangre, saliva, orina, esperma, etc); epidermis, caspa, pelo, heces, una muestra vaginal, una muestra de tejido, tejidos quemados, etc. Las muestras más adecuadas para la obtención de extractos de ADN útiles en la identificación de restos humanos incluyen, entre otros, pelos con raíz, hueso compacto, diente, tejidos blandos y sangre. Examples of samples from which DNA can be obtained are, without limitation, biological fluids (blood, saliva, urine, sperm, etc); epidermis, dandruff, hair, feces, a vaginal sample, a tissue sample, burned tissues, etc. The most suitable samples for obtaining DNA extracts useful in the identification of human remains include, among others, root hairs, compact bone, tooth, soft tissues and blood.
En una realización particular, el extracto de ADN procede de una muestra de sangre, pelo, saliva, epidermis, esperma, caspa, cenizas, una muestra vaginal y una muestra de tejido, In a particular embodiment, the DNA extract comes from a sample of blood, hair, saliva, epidermis, sperm, dandruff, ashes, a vaginal sample and a tissue sample,
La obtención de la muestra biológica debe realizarse en las condiciones y con el material adecuado, tales como torundas, pinzas, etc. y cada muestra debe almacenarse independientemente en frascos o bolsas plásticas separadas y estériles, sin ningún tipo de conservante, en congelación y debidamente rotulados, evitando la contaminación por material biológico foráneo. Una vez que se ha obtenido la muestra del individuo/s o del resto humano, ésta debe ser procesada para obtener el extracto de ADN. La fracción de ADN adecuada para la puesta en práctica de la invención es el ADN nuclear. La extracción del ADN puede ser llevado a cabo usando cualquier método conocido por los expertos en la materia (Sambrock et ai, 2001 "Molecular cloning: a Laboratory Manual", 3rd ed., Cold Spring Harbor Laboratory Press, N.Y., Vol. 1-3) que incluyen sin limitación, centrifugaciones en gradientes de densidad, extracción en dos fases usando fenol acuoso o cloroformo con etanol, cromatografía en columna, métodos basados en la capacidad del ADN para unirse en superficies de cristal y/o silicatos, como preparaciones de tierra diatomeas o lechos de cristal, empleando kits - - Obtaining the biological sample must be carried out under the conditions and with the appropriate material, such as swabs, tweezers, etc. and each sample must be stored independently in separate and sterile plastic jars or bags, without any preservative, in freezing and properly labeled, avoiding contamination by foreign biological material. Once the sample of the individual / s of the human rest has been obtained, it must be processed to obtain the DNA extract. The fraction of DNA suitable for the implementation of the invention is nuclear DNA. DNA extraction may be performed using any method known to those skilled in the art (Sambrook et ai, 2001 "Molecular Cloning: A Laboratory Manual", 3rd ed, Cold Spring Harbor Laboratory Press, NY, Vol . 1. -3) including without limitation, density gradient centrifugations, two-phase extraction using aqueous phenol or chloroform with ethanol, column chromatography, methods based on the ability of DNA to bind on glass surfaces and / or silicates, as preparations of diatomaceous earth or glass beds, using kits - -
comerciales, por ejemplo, los kits "Q-Biogene fast DNA kit" o el "QIAamp(R) DNA Blood Mini Kit" (Qiagen, Hilden, Alemania) el "G-Spin IIp" (Intron Biotechnology, Corea) o el "Fast Prep System Bio 101" (Qbiogene, Madrid, España) o los métodos descritos en US5.057.426, US4.923.978 y la solicitud de patente europea EP0512767A1. commercial, for example, the "Q-Biogene fast DNA kit" or the "QIAamp (R) DNA Blood Mini Kit" (Qiagen, Hilden, Germany) the "G-Spin IIp" (Intron Biotechnology, Korea) or the " Fast Prep System Bio 101 "(Qbiogene, Madrid, Spain) or the methods described in US5,057,426, US4,923,978 and European patent application EP0512767A1.
El extracto de ADN es cuantifícado y normalizado para obtener cantidades iguales de ADN en cada muestra en el caso de que la cantidad de ADN sea suficiente para ello. En el caso de muestras altamente degradadas con ADN escaso y/o degradado es habitual añadir la mayor cantidad de ADN posible en la subsiguiente reacción de PCR multiplex. The DNA extract is quantified and normalized to obtain equal amounts of DNA in each sample in case the amount of DNA is sufficient for it. In the case of highly degraded samples with poor and / or degraded DNA, it is usual to add as much DNA as possible in the subsequent multiplex PCR reaction.
Tras obtener el extracto de ADN de la muestra biológica, éste es sometido, al menos, a una reacción de amplificación multiplex empleando el conjunto de parejas de cebadores de la invención. La amplificación de los diferentes loci STRs requiere condiciones y procedimientos de reacción específicos para cada una de las parejas de cebadores empleadas, las cuales pueden conseguirse mediante variación sistemática de cada parámetro. El número de ciclos y la temperatura de alineamiento empleada en la reacción de PCR deben de ser adecuados para la obtención de resultados mediante cada una de las parejas de cebadores del primer conjunto. Parámetros como la concentración de cebadores son específicos para cada cebador y se han ajustado en la validación del conjunto de cebadores. Los cebadores ofrecen resultados en un amplio rango de concentraciones, aunque las concentraciones óptimas para cada pareja de cebadores se recogen en la Tabla 6. After obtaining the DNA extract from the biological sample, it is subjected, at least, to a multiplex amplification reaction using the set of primer pairs of the invention. The amplification of the different STRs loci requires specific reaction conditions and procedures for each of the pairs of primers used, which can be achieved by systematic variation of each parameter. The number of cycles and the alignment temperature used in the PCR reaction must be suitable for obtaining results by each of the first set of primers. Parameters such as the concentration of primers are specific to each primer and have been adjusted in the validation of the primer set. The primers offer results in a wide range of concentrations, although the optimal concentrations for each pair of primers are shown in Table 6.
Tabla 6. Resumen de las concentraciones a las que se emplea cada uno de los cebadores y el fluorocromo con el que se ha marcado el extremo 5 'del cebador directo o forward (en negrita) de cada pareja de cebadores en el conjunto denominado miniX. Table 6. Summary of the concentrations at which each of the primers is used and the fluorochrome with which the 5 ' end of the direct or forward primer (in bold) of each pair of primers in the set called miniX has been marked.
Figure imgf000028_0001
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Figure imgf000028_0001
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Figure imgf000029_0001
Figure imgf000029_0001
Como entiende el experto en la materia, una reacción de amplificación multiplex requiere una serie de reactivos, entre los que se incluyen, sin limitar a, el ADN molde, la enzima ADN polimerasa, al menos, dos parejas de cebadores (siendo cada cebador de cada pareja complementario a una de las dos hebras del ADN), desoxinucleótidos trifosfatos (dNTPs), cloruro de magnesio (MgC12), buffer de reacción y aditivos opcionales, que pueden añadirse por separado mezclándose en el laboratorio o adquirir previamente mezclados, como es el caso de Multiplex PCR master Mix (Qiagen, Hilden, Germany),o Kapa2GTMFast Multiplex PCR kit ( apa Biosystems, Inc., USA), al que se le añaden las parejas de cebadores en las concentraciones adecuadas y el ADN molde. As the person skilled in the art understands, a multiplex amplification reaction requires a series of reagents, including, but not limited to, the template DNA, the enzyme DNA polymerase, at least two pairs of primers (each primer being each pair complementary to one of the two strands of the DNA), deoxynucleotide triphosphates (dNTPs), magnesium chloride (MgC12), reaction buffer and optional additives, which can be added separately by mixing in the laboratory or purchased previously mixed, as is the case of Multiplex PCR master Mix (Qiagen, Hilden, Germany), or Kapa2GTMFast Multiplex PCR kit (apa Biosystems, Inc., USA), to which the primer pairs are added in the appropriate concentrations and the template DNA.
La PCR se lleva a cabo en un termociclador que realiza los ciclos en los tiempos y temperaturas programadas de forma exacta, tales como la temperatura de hibridación o la temperatura de fusión. The PCR is carried out in a thermal cycler that performs the cycles in the exact times and temperatures programmed, such as the hybridization temperature or the melting temperature.
En una realización particular del método de la invención, la temperatura de fusión de la reacción de amplificación multiplex que comprende los oligonucleótidos SEQ ID NO: 1 a SEQ ID NO. 17 (Tabla 4) es desde 57 a 63°C según lo calculado mediante el programa informático Perlprimer (http://perlprimer.sourceforge.net/). In a particular embodiment of the method of the invention, the melting temperature of the multiplex amplification reaction comprising oligonucleotides SEQ ID NO: 1 to SEQ ID NO. 17 (Table 4) is from 57 to 63 ° C as calculated using the Perlprimer software (http://perlprimer.sourceforge.net/).
La amplificación multiplex del conjunto de parejas de cebadores (Tabla 6) ofrece resultados satisfactorios en un amplio rango de temperaturas de fusión, entre 57-63°C, aunque los mejores resultados se obtienen a 58 °C. De igual manera, los cebadores ofrecen resultados en un amplio rango de concentraciones, aunque las concentraciones óptimas para cada pareja de cebadores se recogen en la Tabla 6. Respecto al número de ciclos empleado en la reacción de PCR se obtienen resultados satisfactorios entre 28-32 ciclos, aunque el número de ciclos óptimo es de 30 ciclos. - - Multiplex amplification of the set of primer pairs (Table 6) offers satisfactory results in a wide range of melting temperatures, between 57-63 ° C, although the best results are obtained at 58 ° C. Similarly, the primers offer results in a wide range of concentrations, although optimal concentrations for each pair of primers are shown in Table 6. Regarding the number of cycles used in the PCR reaction, satisfactory results are obtained between 28-32 cycles, although the optimal number of cycles is 30 cycles. - -
Opcionalmente, si se desea, previamente a la reacción de amplificación multiplex, puede llevarse a cabo el mareaje de los cebadores que participan en dicha reacción de amplificación multiplex con el fin de poder detectar posteriormente los fragmentos amplificados. El mareaje de los productos de amplificación puede realizarse por métodos convencionales. Dicho mareaje puede ser directo, para lo cual pueden utilizarse fluoróforos, por ejemplo, Cy3, Cy5, fluoresceína, alexa, etc., enzimas, por ejemplo, fosfatasa alcalina, peroxidasa, etc., isótopos radiactivos, por ejemplo, 33P, 1251, etc., o cualquier otro marcador conocido por el experto en la materia. Alternativamente, dicho mareaje puede ser indirecto mediante el empleo de métodos químicos, enzimáticos, etc.; a modo ilustrativo, el producto de amplificación puede incorporar un miembro de un par de unión específica, por ejemplo, avidina o estreptavidina conjugada con un fluorocromo (locus), y la sonda se une al otro miembro del par de unión específica, por ejemplo, biotina (indicador), efectuándose la lectura mediante fluorimetría, etc., o bien, el producto de amplificación puede incorporar un miembro de un par de unión específica, por ejemplo, un anticuerpo anti-digoxigenina conjugado con una enzima (locus), y la sonda se une al otro miembro del par de unión específica, por ejemplo, digoxigenina (indicador), etc., transformándose el sustrato de la enzima en un producto luminiscente o fluorescente y , efectuándose la lectura mediante quimio-luminiscencia, fluorimetría, etc. Así, en una realización particular, el mareaje del producto de amplificación se lleva a cabo mediante el mareaje, en uno de sus extremos, de uno de los oligonucleótidos de cada pareja de cebadores. En otra realización todavía más particular, el mareaje de los oligonucleótidos se selecciona del grupo que consiste en un radioisótopo, un material fluorescente, digoxigenina y biotina. Ejemplos de materiales fluorescentes que se pueden emplear en el mareaje de oligonucleótidos incluyen, sin limitar a, 5-carboxifluoresceína (5-FAM), 6-FAM, análogo tetraclorinado de t-FAM (TET), análogo hexaclorinado de 6-FAM (HEX), 6- carboxitetrametilrodamina (TAMRA), 6-carboxi-X-rodamina (ROX), 6-carboxi-4', 5'- dicloro-2', 7 '-dimetoxi fluoresceína (JOE), NED (ABI), Cy-3, Cy-5, Cy-5.5, fluorescein-6- isotiocinato (FITC) y tetrametilrodamina-5-isotiocinato (TRITC). Optionally, if desired, prior to the multiplex amplification reaction, the priming of the primers participating in said multiplex amplification reaction can be carried out in order to be able to subsequently detect the amplified fragments. The marking of amplification products can be carried out by conventional methods. Said marking can be direct, for which fluorophores can be used, for example, Cy3, Cy5, fluorescein, alexa, etc., enzymes, for example, alkaline phosphatase, peroxidase, etc., radioactive isotopes, for example, 33P, 1251, etc., or any other marker known to the person skilled in the art. Alternatively, said marking can be indirect through the use of chemical, enzymatic methods, etc .; by way of illustration, the amplification product may incorporate a member of a specific binding pair, for example, avidin or streptavidin conjugated with a fluorochrome (locus), and the probe binds to the other member of the specific binding pair, for example, biotin (indicator), the reading being carried out by fluorimetry, etc., or the amplification product may incorporate a member of a specific binding pair, for example, an anti-digoxigenin antibody conjugated to an enzyme (locus), and the The probe binds to the other member of the specific binding pair, for example, digoxigenin (indicator), etc., the enzyme substrate is transformed into a luminescent or fluorescent product and the reading is carried out by chemo-luminescence, fluorimetry, etc. Thus, in a particular embodiment, the marking of the amplification product is carried out by marking, at one of its ends, one of the oligonucleotides of each primer pair. In another even more particular embodiment, the oligonucleotide mapping is selected from the group consisting of a radioisotope, a fluorescent material, digoxigenin and biotin. Examples of fluorescent materials that can be used in oligonucleotide mapping include, but are not limited to, 5-carboxyfluorescein (5-FAM), 6-FAM, t-FAM tetrachlorinated analog (TET), 6-FAM hexachlorinated analog (HEX) ), 6- carboxytetramethylrodamine (TAMRA), 6-carboxy-X-rhodamine (ROX), 6-carboxy-4 ', 5'-dichloro-2', 7 '-dimethoxy fluorescein (JOE), NED (ABI), Cy -3, Cy-5, Cy-5.5, fluorescein-6- isothiocinate (FITC) and tetramethylrodamine-5-isothiocinate (TRITC).
Tras finalizar la reacción de amplificación multiplex, si se desea, se puede proceder a separar los productos de amplificación o amplicones. Prácticamente cualquier método convencional puede ser utilizado dentro del marco de la invención para separar los productos de - After completing the multiplex amplification reaction, if desired, the amplification products or amplicons can be separated. Virtually any conventional method can be used within the framework of the invention to separate products from -
amplificación. Las técnicas para separar los productos de amplificación están ampliamente descritas en el estado de la técnica, como por ejemplo, en Sambrook et al, 2001 (citado ad supra). Técnicas para separar los productos de amplificación son, por ejemplo, electroforesis sumergida con geles de Methafor, electroforesis en geles de poliacrilamida, electroforesis capilar, etc. amplification. Techniques for separating amplification products are widely described in the state of the art, such as in Sambrook et al., 2001 (cited ad supra). Techniques for separating amplification products are, for example, submerged electrophoresis with Methafor gels, polyacrylamide gels electrophoresis, capillary electrophoresis, etc.
Seguidamente a la separación de los productos de amplificación, se procede a identificar el tamaño de los fragmentos separados, para lo cual puede emplearse cualquiera de los procedimientos de identificación de fragmentos de amplificación conocidos del estado de la técnica, tales como hibridación con sondas marcadas (por ejemplo con un fiuoróforo) que serán detectadas por un detector y procesadas mediante un sistema informático, tinción, por ejemplo, con bromuro de etidio, tinción de plata, etc. Tal como entiende el experto en la materia, si todo este proceso es integrado en un sistema informático, se puede generar una gráfica denominada electroferograma donde puede identificarse el tamaño de los fragmentos amplificados. it de la invención Following the separation of the amplification products, the size of the separated fragments is identified, for which any of the methods of identification of amplification fragments known in the state of the art can be used, such as hybridization with labeled probes ( for example with a fiuorophore) that will be detected by a detector and processed by a computer system, staining, for example, with ethidium bromide, silver staining, etc. As the person skilled in the art understands, if this whole process is integrated into a computer system, a graph called electropherogram can be generated where the size of the amplified fragments can be identified. it of the invention
Por otro lado, la invención se relaciona con un kit útil para la puesta en práctica del método de la invención, que comprende el conjunto de parejas de cebadores de la invención que comprende 4 o más parejas de cebadores dirigidas a amplificar los loci STRs (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I , DXS 10075 y DXS 10079). On the other hand, the invention relates to a kit useful for the implementation of the method of the invention, comprising the set of primer pairs of the invention comprising 4 or more primer pairs aimed at amplifying the STRs loci (DXS6799 , DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I, DXS 10075 and DXS 10079).
Así, otro aspecto principal de la invención se relaciona con un kit, de aquí en adelante kit de la invención, que comprende parejas de cebadores específicas para amplificar al menos 4 loci STRs seleccionados del grupo formado por los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I , DXS 10075 y DXS 10079, en donde al menos 1 de los 4 loci STRs se selecciona del grupo formado por los loci DXS6799, DXS 10074, DXS6789 y DXS6809; y al menos dos de los 4 loci STRs se selecciona del grupo formado por los loci DXS7132, DXS6801 , DXS 10075 y DXS 10079. - - Thus, another main aspect of the invention relates to a kit, hereinafter kit of the invention, comprising pairs of specific primers to amplify at least 4 STR loci selected from the group formed by loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS680I, DXS 10075 and DXS 10079, where at least 1 of the 4 STRs loci is selected from the group consisting of the DXS6799, DXS 10074, DXS6789 and DXS6809 loci; and at least two of the 4 STRs loci are selected from the group consisting of the DXS7132, DXS6801, DXS 10075 and DXS 10079 loci. - -
En una realización particular, el kit de la invención comprende al menos 5, 6, 7 u 8, parejas de cebadores específicas para los loci STRs del grupo formado por los loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 y DXS10079. En otra realización todavía más particular del kit de la invención, la pareja de cebadores empleada en la reacción de amplificación multiplex específica para cada uno de los loci STR analizados es la pareja de oligonucleótidos mostrada en las secuencias In a particular embodiment, the kit of the invention comprises at least 5, 6, 7 or 8, pairs of primers specific for the STR loci of the group formed by loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 and DXS10079 . In another even more particular embodiment of the kit of the invention, the primer pair used in the multiplex amplification reaction specific to each of the STR loci analyzed is the oligonucleotide pair shown in the sequences.
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799,  - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 1 1 y SEQ ID NO: 12 para el locus DXS680I ,  - SEQ ID NO: 1 1 and SEQ ID NO: 12 for locus DXS680I,
- SEQ ID NO: 13 y/o SEQ ID NO: 14 y/o SEQ ID NO: 15 para el locus DXS 10075, y  - SEQ ID NO: 13 and / or SEQ ID NO: 14 and / or SEQ ID NO: 15 for the DXS 10075 locus, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079.  - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus.
Como entiende el experto en la materia, el kit de la invención además de comprender el conjunto de parejas de cebadores de la invención, puede incluir, opcionalmente, los reactivos necesarios para llevar a cabo la reacción de amplificación multiplex, entre los que se incluyen, sin limitar a, desoxinucleótidos trifosfato (dNTPs), iones divalentes y/o monovalentes, una solución tampón (buffer) que mantiene el pH adecuado para el funcionamiento de la ADN polimerasa, ADN polimerasa o mezcla de distintas polimerasas, etc. No obstante, si el kit de la invención no comprende los reactivos necesarios para poner en práctica el método de la invención, éstos están disponibles comercialmente y pueden encontrarse formando parte de un kit. Cualquier kit de los disponibles comercialmente que contenga los reactivos necesarios para llevar a cabo una reacción de amplificación, puede emplearse con éxito en la puesta en práctica del método de la invención. Tal como se muestra en los ejemplos, en el caso de la presente invención estos reactivos se encuentran previamente mezclados en el reactivo Multiplex PCR master Mix (Qiagen, Hilden, Germany). - - As the person skilled in the art understands, the kit of the invention, in addition to comprising the set of primer pairs of the invention, may optionally include the reagents necessary to carry out the multiplex amplification reaction, including, without limiting to, deoxynucleotides triphosphate (dNTPs), divalent and / or monovalent ions, a buffer solution (buffer) that maintains the proper pH for the functioning of DNA polymerase, DNA polymerase or mixture of different polymerases, etc. However, if the kit of the invention does not comprise the reagents necessary to practice the method of the invention, these are commercially available and can be found as part of a kit. Any commercially available kit containing the reagents necessary to carry out an amplification reaction can be used successfully in the practice of the method of the invention. As shown in the examples, in the case of the present invention these reagents are previously mixed in the Multiplex PCR master Mix reagent (Qiagen, Hilden, Germany). - -
Tal como se ha descrito en párrafos anteriores, previamente a la reacción de amplificación multiplex del método de la invención, si se desea puede llevarse a cabo el mareaje de los cebadores con el fin de poder detectar posteriormente los fragmentos amplificados. De forma análoga, como entiende el experto en la materia, el kit de la invención puede comprender el primer conjunto de parejas de cebadores de la invención en donde uno de los oligonucléotidos de cada pareja de cebadores está marcado en uno de sus extremos o, alternativamente, puede comprender los reactivos necesarios para llevar a cabo el mareaje de los cebadores. Los distintos métodos que existen en el estado de la técnica para realizar el mareaje de los cebadores, así como los tipos de marcadores que se puede emplear han sido explicados previamente en la presente memoria. As described in previous paragraphs, prior to the multiplex amplification reaction of the method of the invention, if desired the priming of the primers can be carried out in order to be able to subsequently detect the amplified fragments. Similarly, as the person skilled in the art understands, the kit of the invention may comprise the first set of primer pairs of the invention wherein one of the oligonucleotides of each pair of primers is labeled at one of its ends or, alternatively , may comprise the reagents necessary to carry out the priming of the primers. The different methods that exist in the state of the art to perform the mareaje of the primers, as well as the types of markers that can be used have been previously explained herein.
Así, en una realización particular, el kit de la invención comprende, además, los reactivos necesarios para marcar las parejas de nucleótidos. En otra realización particular uno de los oligonucléotidos de cada pareja de cebadores está marcado en uno de sus extremos. Thus, in a particular embodiment, the kit of the invention further comprises the reagents necessary to label the nucleotide pairs. In another particular embodiment one of the oligonucleotides of each pair of primers is labeled at one of its ends.
En una realización todavía más particular del kit de la invención, los marcadores empleados en el mareaje de los oligonucléotidos seleccionan del grupo que consiste en un radioisótopo, un material fluorescente, digoxigenina y biotina. En otra realización aún más particular, el material fluorescente se selecciona del grupo que consiste en 5-carboxifluoresceína (5-FAM), 6-FAM, análogo tetraclorinado de t-FAM (TET), análogo hexaclorinado de 6-FAM (HEX), 6- carboxitetrametilrodamina (TAMRA), 6-carboxi-X-rodamina (ROX), 6-carboxi-4', 5'- dicloro-2', 7'-dimetoxifluoresceína (JOE), NED (ABI), Cy-3, Cy-5, Cy-5.5, fluorescein-6- isotiocinato (FITC) y tetrametilrodamina-5-ísotiocinato (TRITC). Tal como se ha mencionado previamente, el kit de la invención es útil en la puesta en práctica del método de invención. Por lo tanto, su empleo permitirá obtener el perfil genético de un individuo, determinar relaciones de parentesco entre individuos o identificar restos humanos. In an even more particular embodiment of the kit of the invention, the markers used in the oligonucleotide mapping select from the group consisting of a radioisotope, a fluorescent material, digoxigenin and biotin. In another even more particular embodiment, the fluorescent material is selected from the group consisting of 5-carboxyfluorescein (5-FAM), 6-FAM, t-FAM tetrachlorinated analog (TET), 6-FAM hexachlorinated analog (HEX), 6- carboxytetramethylrodamine (TAMRA), 6-carboxy-X-rhodamine (ROX), 6-carboxy-4 ', 5'-dichloro-2', 7'-dimethoxyfluorescein (JOE), NED (ABI), Cy-3, Cy-5, Cy-5.5, fluorescein-6- isothiocinate (FITC) and tetramethylrodamine-5-isothiocinate (TRITC). As previously mentioned, the kit of the invention is useful in the implementation of the method of invention. Therefore, its use will allow obtaining the genetic profile of an individual, determining kinship relationships between individuals or identifying human remains.
Los siguientes ejemplos son ilustrativos de la invención y no pretenden ser limitativos de la misma. The following examples are illustrative of the invention and are not intended to be limiting thereof.
EJEMPLOS - - EXAMPLES - -
En los ejemplos siguientes se realiza la validación de miniX, para su uso en identificación humana. Ejemplo 1. En el primer ejemplo se detalla la optimización de los conjuntos de cebadores y de los parámetros de las reacciones de PCR, así como los estudios de cociente entre la altura de heterocigotos (PHR, peak height ratio), bandas tartamudas (stutter bands) y sensibilidad. In the following examples the validation of miniX is performed, for use in human identification. Example 1. In the first example, the optimization of the primer sets and the parameters of the PCR reactions is detailed, as well as the studies of the ratio between the height of heterozygotes (PHR), stutter bands (stutter bands) ) and sensitivity.
Ejemplo 2. En el segundo ejemplo, se muestra la validación del método de la invención que comprende la reacción de amplificación multiplex para su uso en el análisis de muestras de ADN altamente degradadas, con el objetivo de demostrar que la invención es adecuada para su uso en este tipo de muestras. Example 2. In the second example, the validation of the method of the invention comprising the multiplex amplification reaction is shown for use in the analysis of highly degraded DNA samples, in order to demonstrate that the invention is suitable for use. In this type of samples.
EJEMPLO 1 EXAMPLE 1
Validación del método de la invención que comprende una reacción de amplificación multiplex empleando los conjuntos de parejas de cebadores miniX para su uso en identificación humana A continuación se describe la validación de miniX para su uso en identificación humana. Dicha validación ha consistido en ensayos de optimización de los conjuntos de cebadores, optimización de los parámetros de la PCR y estudios de concordancia.  Validation of the method of the invention comprising a multiplex amplification reaction using sets of miniX primer pairs for use in human identification The validation of miniX for use in human identification is described below. This validation has consisted of optimization tests of the primer sets, optimization of the PCR parameters and concordance studies.
Los resultados obtenidos mostraron que miniX es una herramienta adecuada para la obtención de perfiles genéticos humanos. The results obtained showed that miniX is a suitable tool for obtaining human genetic profiles.
MATERIALES Y METODOS MATERIALS AND METHODS
Muestras control de ADN humano Control samples of human DNA
Se utilizaron los ADN controles 9947A del kit AmpFISTR® YFiler (Applied Biosystems, Foster City, CA) y K562 (Promega® Corporation, USA) para poner a punto las condiciones de PCR. Estas dos muestras se cuantificaron mediante Quant-iT™ dsDNA HS Assay Kit - - 9947A control DNAs from the AmpFISTR ® YFiler kit (Applied Biosystems, Foster City, CA) and K562 (Promega® Corporation, USA) were used to tune the PCR conditions. These two samples were quantified using Quant-iT ™ dsDNA HS Assay Kit - -
(Invitrogen, Carlsbad, CA), de acuerdo con las especificaciones del fabricante y fueron diluidas a 0,5 ng/μΐ. (Invitrogen, Carlsbad, CA), according to the manufacturer's specifications and were diluted to 0.5 ng / μΐ.
Muestras de la población Population samples
Se tomaron muestras de saliva de 439 individuos sanos: 365 residentes en Santander (Cantabria, España) agrupados en 1 16 familias y 74 habitantes de la Vega de Pas (Cantabria, España) agrupados en 22 familias. En todos los casos las familias estaban constituidas al menos por abuelo paterno, madre e hijo. Extracción de ADN y cuantificación Saliva samples were taken from 439 healthy individuals: 365 residents in Santander (Cantabria, Spain) grouped into 1,116 families and 74 inhabitants of Vega de Pas (Cantabria, Spain) grouped into 22 families. In all cases the families were constituted at least by paternal grandfather, mother and son. DNA extraction and quantification
Los extractos de ADN procedentes de las muestras poblacionales se obtuvieron mediante extracción por Prep Mini Spin kit (GE Healthcare Spain, Barcelona,  DNA extracts from population samples were obtained by extraction by Prep Mini Spin kit (GE Healthcare Spain, Barcelona,
Spain). La cuantificación de los extractos de ADN se realizó mediante Quant-iT™ dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA).  Spain). Quantification of DNA extracts was performed using Quant-iT ™ dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA).
Optimización del conjunto de cebadores Primer set optimization
Se utilizó el programa Perlprimer (http://perlprimer.sourceforge.net/) para diseñar nuevos cebadores que amplifiquen 8 loci STRs (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079), en base a las secuencias de referencia cuyos números de acceso a GeneBank se recogen en la Tabla 7.  The Perlprimer program (http://perlprimer.sourceforge.net/) was used to design new primers that amplify 8 STR loci (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079), based on the reference sequences whose access numbers to GeneBank are shown in Table 7.
Las regiones flanqueantes a los STR analizados se estudiaron mediante SNPblast www.ncbi.nlm.nih.gov/SNP/snpblastByChr.html) con el fin de evitar posiciones variables en la región de unión de todos los cebadores diseñados. Los amplificados se extienden desde 101 hasta 219 pb, para abarcar un amplio número de los alelos contenidos en las publicaciones de referencia detalladas en la tabla 1 , confeccionada en base a la información recogida en ChrX- STR.org 2.0 [http://www.chrx-str.org]. The flanking regions to the STRs analyzed were studied using SNPblast www.ncbi.nlm.nih.gov/SNP/snpblastByChr.html) in order to avoid variable positions in the junction region of all designed primers. The amplifiers range from 101 to 219 bp, to cover a large number of the alleles contained in the reference publications detailed in Table 1, made based on the information collected in ChrX-STR.org 2.0 [http: // www .chrx-str.org].
Para evitar la adenilación incompleta se utilizó la adición de una guanina al extremo 5' del cebador inverso (secuencia 15 de la tabla 5) para el locus DXS 10075 (Brownstein et al., 1996 Biotechniques 20(6): 1004-1006; Hill et al., 2009 J. Forensic Sci. 54(5): 7; Butler et al., 2003 J. Forensic Sci. 48(5): 1054-1064). - - To avoid incomplete adenylation, the addition of a guanine to the 5 'end of the reverse primer (sequence 15 of table 5) was used for the DXS 10075 locus (Brownstein et al., 1996 Biotechniques 20 (6): 1004-1006; Hill et al., 2009 J. Forensic Sci. 54 (5): 7; Butler et al., 2003 J. Forensic Sci. 48 (5): 1054-1064). - -
Tabla 7.Número de acceso a GenBank, Rango de alelos, tamaño del producto (bp), concentración del cebador y mareaje fluorescente para cada locus de iniX. Table 7. GenBank access number, Allele range, product size (bp), primer concentration and fluorescent marking for each iniX locus.
Figure imgf000036_0001
Figure imgf000036_0001
*Hering S, et al. 2007. EXCLI Journal, 6: 177-182. * Hering S, et al. 2007. EXCLI Journal, 6: 177-182.
Amplificación de PCR, electroforesis y análisis de datos PCR amplification, electrophoresis and data analysis
Se emplearon 5μ1 de Multiplex PCR master Mix (Qiagen, Hilden, Germany), 1,58 μΐ del mix de cebadores, 2,42 μΐ de H20 mQ estéril y 1 μΐ de ADN molde (0,5ng / μΐ). Las concentraciones de cada pareja de cebadores se detallan en la Tabla 7. Se analizó el rendimiento de la amplificación en un termaciclador GeneAmp® 9700 PCR System (Applied Biosystems, Foster City, CA), en diferentes condiciones de temperaturas de hibridación ("annealing temperature"): 57 °C, 58 °C, 60,5 °C, 61 ,8 °C y 63 °C, a distintos números de ciclos: 28, 29, 30, 31 y 32 ciclos y a tiempos de extensión final de 30, 45, 60 y 90 minutos. Se analizó 2 μΐ de cada producto de amplificado mezclados con 9 μΐ de Hi-Di™ Formamide (Applied Biosystems®, Foster City, CA) y 0,3 μΐ de GeneScan™ 500 LIZ® Size Standard (Applied Biosystems®, Foster City, CA). Tras la desnaturalización de los amplificados (5 minutos a 95 °C) se enfriaron (5 minutos a 4 °C) y se separaron en un ABI PRISM 310 Genetic Analyzer (Applied Biosystems®, Foster City, CA), Los resultados de la electroforesis fueron analizados mediante el software Genmapper versión 3.2 (Applied Biosystems®, Foster City, CA). 5μ1 of Multiplex PCR master Mix (Qiagen, Hilden, Germany), 1.58 μΐ of the primer mix, 2.42 μΐ of sterile H 2 0 mQ and 1 μΐ of template DNA (0.5ng / μΐ) were used. The concentrations of each pair of primers are detailed in Table 7. The amplification performance was analyzed in a GeneAmp ® 9700 PCR System (Applied Biosystems, Foster City, CA) thermocycler, under different conditions of hybridization temperatures ("annealing temperature""): 57 ° C, 58 ° C, 60.5 ° C, 61, 8 ° C and 63 ° C, at different numbers of cycles: 28, 29, 30, 31 and 32 cycles and at final extension times of 30 , 45, 60 and 90 minutes. 2 μΐ of each amplifier product was analyzed mixed with 9 μΐ of Hi-Di ™ Formamide (Applied Biosystems ® , Foster City, CA) and 0.3 μΐ of GeneScan ™ 500 LIZ ® Size Standard (Applied Biosystems ® , Foster City, AC). After the denaturation of the amplified (5 minutes at 95 ° C) they were cooled (5 minutes at 4 ° C) and separated in an ABI PRISM 310 Genetic Analyzer (Applied Biosystems ® , Foster City, CA), Electrophoresis results were analyzed using Genmapper software version 3.2 (Applied Biosystems ® , Foster City, CA).
Estudios de concordancia Concordance studies
Se compararon perfiles genéticos analizados con miniX, Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57(1): 192- 195) y Decaplex (Gusmao et. al., 2009 Int. J. Legal Med. 123 (3): 227- 234). Para su análisis mediante miniX se empleó 0,5 ng de ADN molde de cada individuo. El análisis mediante Sextaplex y Decaplex se realizó según las condiciones óptimas previamente descritas por los respectivos autores (Castañeda et al., 2012 J. Forensic Sci. 7(1): 192- 195; Gusmao et. al., 2009 Int. J. Legal Med. 123 (3): 227- 234). - - Genetic profiles analyzed with miniX, Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195) and Decaplex (Gusmao et. Al., 2009 Int. J. Legal Med. 123 (3 ): 227-234). For its analysis by miniX, 0.5 ng of template DNA from each individual was used. The analysis by Sextaplex and Decaplex was performed according to the optimal conditions previously described by the respective authors (Castañeda et al., 2012 J. Forensic Sci. 7 (1): 192-195; Gusmao et. Al., 2009 Int. J. Legal Med. 123 (3): 227-234). - -
RESULTADOS Optimización de los conjuntos de cebadores RESULTS Optimization of primer sets
La Tabla 7 recoge un amplio rango de alelos para cada locus incluido en miniX. Se han considerado los alelos descritos en los principales grupos poblacionales según la información recogida en ChrX-STR.org 2.0 [http://www.chrx-str.org]. Se diseñaron 37 cebadores de entre los que se eligieron aquellos capaces de producir amplificados del menor tamaño posible, que en ningún caso excedieran de 220 pb, cuyas temperaturas de fusión ("melting temperature") estuvieran comprendidas entre 57,5 y 60,5 °C y que hibridaran en regiones carentes de SNPs {Single Nucleotide Polymorphism) e INDELS (Inserciones/deleciones) descrito hasta la fecha en NCBI (http://www.ncbi.nlm.nih.gov/snp/). El diseño de los cebadores degenerados (degenerate primers) para el locus DXS 10075 fue necesario para permitir la hibridación al sitio de unión del cebador, debido a que se encontró un SNP (rs945048 A/T) cercano a la unidad de repetición de dicho STR. En la primera fase de optimización se efectuaron amplificaciones PCR singleplex de cada locus. En la segunda fase de optimización, se ensayaron diversos conjuntos de cebadores en multiplex. Se espaciaron los rangos de alelos de los loci adyacentes en tamaño con el fin de evitar solapamientos entre alelos correspondientes a loci diferentes para asegurar así un correcto genotipado.  Table 7 shows a wide range of alleles for each locus included in miniX. The alleles described in the main population groups have been considered according to the information collected in ChrX-STR.org 2.0 [http://www.chrx-str.org]. 37 primers were designed from which those capable of producing amplifiers of the smallest possible size were chosen, which in no case exceeded 220 bp, whose melting temperatures were between 57.5 and 60.5 ° C and that hybridize in regions lacking SNPs {Single Nucleotide Polymorphism) and INDELS (Insertions / deletions) described to date in NCBI (http://www.ncbi.nlm.nih.gov/snp/). The degenerate primers (degenerate primers) design for the DXS 10075 locus was necessary to allow hybridization to the primer binding site, because an SNP (rs945048 A / T) was found close to the repeat unit of said STR . In the first phase of optimization, singleplex PCR amplifications of each locus were performed. In the second optimization phase, various sets of multiplex primers were tested. The allele ranges of adjacent loci in size were spaced in order to avoid overlaps between alleles corresponding to different loci to ensure proper genotyping.
Finalmente, se seleccionaron 4 reacciones de PCR dúplex (dúplex A:DXS6799 y DXS 10074 ; dúplex B: DXS6789 y DXS6809 ; dúplex C: DXS7132 y DXS6801 y dúplex D: DXS 100075 y DXS 10079). Finally, 4 duplex PCR reactions (duplex A: DXS6799 and DXS 10074; duplex B: DXS6789 and DXS6809; duplex C: DXS7132 and DXS6801 and duplex D: DXS 100075 and DXS 10079) were selected.
Los cebadores directos de la reacciones dúplex A, B, C y D se marcaron respectivamente con los marcadores fluorescentes 6-FAM™, NED™, VIC™ y PET® (Applied Biosystems, Foster City, CA),tal y como se detalla en la Tabla 7. La única excepción la constituye DXS 10075 donde se marcó el cebador reverso con PET®. Por último, se agruparon los distintos conjuntos de cebadores en una única reacción de PCR multiplex que permite la amplificación de 8 loci STRs. En la Figura 2 se representa el resultado final de la estrategia en el diseño de cebadores para miniX. - - Forward primers duplex A, B, C and D reactions is labeled respectively with the fluorescent labels 6-FAM ™, NED ™, VIC ™ and PET ® (Applied Biosystems, Foster City, CA), as detailed in Table 7. The only exception is DXS 10075 where the reverse primer was marked with PET ® . Finally, the different sets of primers were grouped in a single multiplex PCR reaction that allows the amplification of 8 STRs loci. Figure 2 shows the final result of the strategy in the design of primers for miniX. - -
En conclusión, para posibilitar la obtención del perfil genético completo se diseñaron los cebadores de tal modo que pudiesen ser analizados en una única reacción multiplex un total de 8 loci STRs: (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079). In conclusion, to enable the complete genetic profile to be obtained, primers were designed so that a total of 8 STRs loci could be analyzed in a single multiplex reaction: (DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079).
Optimización de los parámetros de PCR PCR parameter optimization
La optimización de los parámetros de amplificación tales como la concentración óptima de cebadores, temperatura de hibridación, número de ciclos y tiempo de extensión, se realizó mediante el estudio de los electro ferogramas en los que se evaluó la altura de los picos, el balance en heterocigosis de los mismos y la adenilación incompleta. En primer lugar, la concentración de cada pareja de cebadores fue testada entre 0,04 μΜ y 0,6 μΜ, de tal forma que en cada caso, por debajo de la concentración óptima se observó un aumento en la altura de los picos a medida que se aumentaba la concentración de cebadores. Mientras que a su vez, en concentraciones superiores a la considerada óptima se detectó un aumento tanto del desbalance en heterocigosis como de la adenilación incompleta. The optimization of the amplification parameters such as the optimal concentration of primers, hybridization temperature, number of cycles and extension time, was carried out by studying the electro ferograms in which the height of the peaks was evaluated, the balance in heterozygous thereof and incomplete adenylation. First, the concentration of each pair of primers was tested between 0.04 μΜ and 0.6 μΜ, so that in each case, below the optimum concentration an increase in the height of the peaks was observed as that the concentration of primers was increased. While at the same time, in concentrations higher than the one considered optimal, an increase in both imbalance in heterozygosis and incomplete adenylation was detected.
En este sentido, las intensidades de los loci analizados mediante miniX se equilibró alrededor de de 2500 RFUs en homocigóticos, y 1500 en heterocigóticos, en el análisis de 0,5 ng de ADN, para alcanzar un equilibrio entre la intensidad de la señal y la ausencia de solapamiento entre las señales correspondientes a diferentes fluorocromos. (Figura 1). In this sense, the intensities of the loci analyzed by miniX were balanced around 2500 RFUs in homozygous, and 1500 in heterozygous, in the analysis of 0.5 ng of DNA, to achieve a balance between the intensity of the signal and the absence of overlap between the signals corresponding to different fluorochromes. (Figure 1).
A continuación se procedió a la optimización de la temperatura de hibridación de la reacción PCR multiplex. El aumento de temperatura de hibridación produjo una disminución gradual de la adenilación incompleta, pero también de la altura de los picos. Los mejores resultados se obtuvieron a la temperatura de hibridación de 58 °C. The hybridization temperature of the multiplex PCR reaction was then optimized. The increase in hybridization temperature produced a gradual decrease in incomplete adenylation, but also in the height of the peaks. The best results were obtained at the hybridization temperature of 58 ° C.
Por otro lado, el aumento en el número de ciclos incrementó de forma generalizada la altura de los picos y la adenilación incompleta. En este sentido, los resultados más equilibrados correspondieron a 30 ciclos. Así mismo la adición de una guanina al extremo 5' del primer - - On the other hand, the increase in the number of cycles generally increased the height of the peaks and incomplete adenylation. In this sense, the most balanced results corresponded to 30 cycles. Also the addition of a guanine to the 5 'end of the first - -
reverse eliminó el efecto de la adenilación incompleta. La adición de dicha guanina se representa como una G en la Tabla 5. reverse eliminated the effect of incomplete adenylation. The addition of said guanine is represented as a G in Table 5.
De esta manera, miniX ha demostrado ser una reacción multiplex balanceada y específica, capaz de amplificar 8 loci STRs, a partir de 0,5 ng de ADN molde (Figura 1), mediante la siguientes condiciones de amplificación: un ciclo de desnaturalización inicial durante 15 minutos a 95 °C, 30 ciclos de 30 s a 94 °C, 90 s a 58 °C y 60 s a 72 °C, seguidos de I ciclo de extensión final de 60 minutos a 60 °C. Estudios de concordancia In this way, miniX has proven to be a balanced and specific multiplex reaction, capable of amplifying 8 STRs loci, from 0.5 ng of template DNA (Figure 1), by the following amplification conditions: an initial denaturation cycle during 15 minutes at 95 ° C, 30 cycles of 30 s at 94 ° C, 90 s at 58 ° C and 60 s at 72 ° C, followed by the final 60 minute extension cycle at 60 ° C. Concordance studies
Los estudios de concordancia se llevaron a cabo mediante la comparación del genotipado de 1670 alelos obtenidos por miniX y Decaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 (3):227- 234) y la comparación de genotipado de 3343 alelos obtenidos mediante miniX y Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57( 1 ):192-195). Se eligió Decaplex ser una reacción de análisis de STRs del cromosoma X ampliamente utilizados y validados (Gusmao et al., 2009 Int. J. Legal Med. 123 (3):227- 234). Sextaplex, se eligió por tratarse igualmente de una reacción validada, así como porque mediante miniX se analiza la totalidad de los loci STRs incluidos en dicha reacción (Castañeda et al., 2012 J. Forensic Sci. 57( 1): 192- 195). Entre los resultados obtenidos no se encontraron discordancias, lo que supone una concordancia del 100% entre las tres reacciones multiplex.  Concordance studies were carried out by comparing the genotyping of 1670 alleles obtained by miniX and Decaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 (3): 227-234) and comparing genotyping of 3343 alleles obtained by miniX and Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195). Decaplex was chosen to be an analysis reaction of widely used and validated X-chromosome STRs (Gusmao et al., 2009 Int. J. Legal Med. 123 (3): 227-234). Sextaplex was chosen because it is also a validated reaction, as well as because miniX analyzes all the STR loci included in that reaction (Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195) . Among the results obtained, no disagreements were found, which means 100% concordance between the three multiplex reactions.
DISCUSION DISCUSSION
A continuación se discuten los resultados relativos a la validación de miniX en los ensayos de optimización del conjunto de cebadores, optimización de parámetros de PCR, y estudios de concordancia. The results related to the validation of miniX in the trials of primer set optimization, PCR parameter optimization, and concordance studies are discussed below.
MiniX ha demostrado ser una reacción multiplex balanceada y específica, capaz de amplificar 8 loci STRs. De este modo miniX es la única reacción capaz de analizar de manera simultánea - - MiniX has proven to be a balanced and specific multiplex reaction, capable of amplifying 8 STRs loci. In this way miniX is the only reaction capable of analyzing simultaneously - -
los loci STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079. the STRX DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci.
La ftabilidad de miniX ha sido comprobada mediante estudios de concordancia entre los perfiles genéticos determinados por este sistema y los obtenidos mediante sistemas preexistentes ampliamente utilizados y validados como son Decaplex y Sextaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 (3):227- 234 ; Castañeda et al., 2012 J. Forensic Sci. 57( 1):192-195). En este sentido se constató la concordancia del 100 % entre los resultados de las tres reacciones comparadas. Sextaplex comparte 6 de los loci STRs incluidos en miniX (DXS 10074, DXS6789, DXS6809, DXS6801, DXS 10075 y DXS 10079). Mientras que Decaplex comparte 3 de los loci STRs incluidos en miniX (DXS6789, DXS6809 y DXS7 I32). De modo que mediante la comparación con ambas reacciones se realizaron estudios de concordancia de 7 de los 8 loci STRs incluidos en miniX, con la excepción del locus DXS6799, que previo a este estudio ha sido incluido en la reacción multiplex de 4 loci STRs de Liu et al., 2009 Legal Medicine l l(5):248-250 en la muestra poblacional de 400 individuos (200 hombres y 200 mujeres procedentes del grupo étnico Han de Beijing, China) (en la base de datos ChrX-STR.org 2.0 ["http://www.chrx-str.Org/1 no aparece ningún dato poblacional). Por lo tanto, en base a los resultados obtenidos en los estudios de concordancia los perfiles genéticos obtenidos mediante miniX mostraron una alta fiabilidad. The miniX ftability has been verified by concordance studies between the genetic profiles determined by this system and those obtained through widely used and validated pre-existing systems such as Decaplex and Sextaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 ( 3): 227-234; Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195). In this sense, 100% concordance was observed between the results of the three reactions compared. Sextaplex shares 6 of the STR loci included in miniX (DXS 10074, DXS6789, DXS6809, DXS6801, DXS 10075 and DXS 10079). While Decaplex shares 3 of the STR loci included in miniX (DXS6789, DXS6809 and DXS7 I32). So, by comparing both reactions, concordance studies of 7 of the 8 STR loci included in miniX were performed, with the exception of the DXS6799 locus, which prior to this study has been included in the Liu STRs 4 loci multiplex reaction et al., 2009 Legal Medicine ll (5): 248-250 in the population sample of 400 individuals (200 men and 200 women from the Han ethnic group in Beijing, China) (in the ChrX-STR.org 2.0 database [ " http://www.chrx-str.Org/1 no population data appears). Therefore, based on the results obtained in the concordance studies, the genetic profiles obtained through miniX showed high reliability.
En conclusión, la presente validación ha puesto de manifiesto que miniX constituye un sistema de elevada robustez y fiabilidad en la obtención de perfiles genéticos, lo que las convierte en una herramienta útil para su utilización en identificación humana. Así mismo, el reducido tamaño de sus amplificados menores en su totalidad a 219 pb, sugiere que la presente invención posee una elevada capacidad de análisis de los loci DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079. EJEMPLO 2 In conclusion, this validation has shown that miniX is a system of high robustness and reliability in obtaining genetic profiles, which makes them a useful tool for use in human identification. Likewise, the small size of its amplifiers smaller in its totality at 219 bp, suggests that the present invention has a high analysis capacity of the DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci. EXAMPLE 2
V alidación del método de la invención que comprende una reacción de amplificación multiplex empleando los conjuntos de parejas de cebadores miniX para su uso en el análisis de muestras de ADN altamente degradadas - - Validation of the method of the invention comprising a multiplex amplification reaction using sets of miniX primer pairs for use in the analysis of highly degraded DNA samples - -
A continuación se describe la validación de miniX y la combinación de ambas reacciones de acuerdo con Scientific Working Group on DNA Analysis Methods (SGWDAM) (Ellegren., 2004 Nat. Rev. Genet. 5(6): 435-45) en el análisis de muestras de ADN altamente degradadas. Dicha validación ha consistido en ensayos de determinación de porcentaje de alelos tartamudos, intensidad relativa entre picos, y sensibilidad. Así mismo, se realizan dos estudios comparativos de: 1) entre las estrategias de diseño del método objeto de invención y los de los métodos del estado de la técnica y 2) entre la capacidad de análisis a partir de muestras de ADN altamente degradadas del método de la invención por un lado, y por otro la capacidad de análisis de Decaplex (Gusmáo et al., 2009 Int. J. Legal Med. 123 (3):227- 234) y Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57(1): 192-195), por ser los métodos del estado de la técnica que mayor rendimiento han demostrado en el estudio de los Ioci STRs incluidos en el método objeto de invención. Los resultados obtenidos indican que la presente invención supera al resto de métodos de la técnica en capacidad de análisis del conjunto de los loci STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 y DXS 10079, a partir de muestras de ADN altamente degradadas. MATERIALES Y METODOS The validation of miniX and the combination of both reactions according to Scientific Working Group on DNA Analysis Methods (SGWDAM) (Ellegren., 2004 Nat. Rev. Genet. 5 (6): 435-45) in the analysis are described below. of highly degraded DNA samples. This validation has consisted of tests to determine the percentage of stuttering alleles, relative intensity between peaks, and sensitivity. Likewise, two comparative studies are carried out: 1) between the design strategies of the method object of the invention and those of the prior art methods and 2) between the ability to analyze from highly degraded DNA samples of the method of the invention on the one hand, and on the other the ability to analyze Decaplex (Gusmáo et al., 2009 Int. J. Legal Med. 123 (3): 227-234) and Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195), as the state of the art methods that have shown the highest performance in the study of the Ioci STRs included in the method object of the invention. The results obtained indicate that the present invention surpasses the rest of the methods of the technique capable of analyzing the whole of the STRX DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 and DXS 10079 loci, from DNA samples highly degraded MATERIALS AND METHODS
Muestras control de ADN humano Control samples of human DNA
Se utilizó el ADN control K562 (Promega® Corporation, USA) para realizar ensayos de sensibilidad. Esta muestra se cuantifícó mediante Quant-iT™ dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA) de acuerdo con las especificaciones del fabricante y fue diluida a 0,5 ng/μΐ.  K562 control DNA (Promega® Corporation, USA) was used to perform sensitivity assays. This sample was quantified using Quant-iT ™ dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA) according to the manufacturer's specifications and was diluted to 0.5 ng / μΐ.
Muestras de la población Population samples
Se tomaron muestras de saliva de 439 individuos sanos: 365 residentes en Santander (Cantabria, España) agrupados en 1 16 familias y 74 habitantes de la Vega de Pas (Cantabria, España) agrupados en 22 familias. En todos los casos las familias estaban constituidas al menos por abuelo paterno, madre e hijo. - Saliva samples were taken from 439 healthy individuals: 365 residents in Santander (Cantabria, Spain) grouped into 1,116 families and 74 inhabitants of Vega de Pas (Cantabria, Spain) grouped into 22 families. In all cases the families were constituted at least by paternal grandfather, mother and son. -
Muestras de ADN altamente degradadas. Highly degraded DNA samples.
Se tomaron 24 muestras de ADN procedentes de tejidos incluidos en parafina, originarios de autopsias en las que el tejido permaneció 72-96 horas en formo! antes de su inclusión en parafina.  24 DNA samples were taken from tissues included in paraffin, originating from autopsies in which the tissue remained 72-96 hours in shape! before inclusion in paraffin.
Extracción de ADN y cuantificación DNA extraction and quantification
Los extractos de ADN procedentes de las muestras poblacionales se obtuvieron mediante extracción por Prep Mini Spin kit (GE Healthcare Spain, Barcelona, Spain) y los procedentes de parafina por cobas® DNA Sample Preparation Kit (Roche Roche Diagnostics SL, Barcelona, Spain). La cuantificación de los extractos de ADN se realizó mediante Quant- iT™ dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA).  DNA extracts from population samples were obtained by extraction by Prep Mini Spin kit (GE Healthcare Spain, Barcelona, Spain) and those from paraffin by cobas® DNA Sample Preparation Kit (Roche Roche Diagnostics SL, Barcelona, Spain). Quantification of DNA extracts was performed using Quant-iT ™ dsDNA HS Assay Kit (Invitrogen, Carlsbad, CA).
Amplificación de PCR, electroforesis y análisis de datos PCR amplification, electrophoresis and data analysis
Se emplearon 5μ1 de Multiplex PCR master Mix (Qiagen, Hilden, Germany), 1,58 μΐ del mix de cebadores y 2,42 μΐ de H20 mQ estéril. Para la amplificación de las muestras de ADN procedentes de muestras poblacionales se utilizó 1 μ| de ADN molde (0,5ng / μΐ), mientras que para la amplificación de ias muestras de ADN procedentes de tejidos incluidos en parafina se empleó 1 μΐ de ADN molde (3 ng / μΐ). Las concentraciones de cada pareja de cebadores se detallan en la Tabla 7. 5μ1 of Multiplex PCR master Mix (Qiagen, Hilden, Germany), 1.58 μΐ of the primer mix and 2.42 μΐ of sterile H 2 0 mQ were used. For the amplification of DNA samples from population samples, 1 μ | of template DNA (0.5ng / μΐ), while 1 μificación of template DNA (3 ng / μΐ) was used to amplify the DNA samples from paraffin-included tissues. The concentrations of each pair of primers are detailed in Table 7.
La amplificación se realizó en un termociclador GeneAmp® 9700 PCR System (Applied Biosystems, Foster City, CA), en las siguientes condiciones: un ciclo de desnaturalización inicial durante 15 minutos a 95 °C, 30 ciclos de 30 s a 94 °C, 90 s a 58 °C y 60 s a 72 °C, seguidos de I ciclo de extensión final de 60 minutos a 60 °C. The amplification was performed in a GeneAmp ® 9700 PCR System thermocycler (Applied Biosystems, Foster City, CA), under the following conditions: an initial denaturation cycle for 15 minutes at 95 ° C, 30 cycles of 30 s at 94 ° C, 90 at 58 ° C and 60 s at 72 ° C, followed by the final 60 minute extension cycle at 60 ° C.
Se analizaron 2 μΙ de cada producto de amplificado mezclados con 9 μΐ de Hi-Di™ Formamide (Applied Biosystems®, Foster City, CA) y 0,3 μΐ de GeneScan™ 500 LIZ® Size Standard (Applied Biosystems®, Foster City, CA). Tras la desnaturalización de los amplificados (5 minutos a 95 °C) se enfriaron (4 minutos a 4 °C) y se separaron en un AB1 PRISM 310 Genetic Analyzer (Applied Biosystems®, Foster City, CA). Los resultados de la electroforesis fueron analizados mediante el software Genmapper versión 3.2 (Applied Biosystems®, Foster City, CA). - - 2 μΙ of each amplifier product mixed with 9 μΐ of Hi-Di ™ Formamide (Applied Biosystems ® , Foster City, CA) and 0.3 μΐ of GeneScan ™ 500 LIZ ® Size Standard (Applied Biosystems ® , Foster City,) were analyzed. AC). After denaturation of the amplified (5 minutes at 95 ° C), they were cooled (4 minutes at 4 ° C) and separated into an AB1 PRISM 310 Genetic Analyzer (Applied Biosystems ® , Foster City, CA). The electrophoresis results were analyzed using Genmapper software version 3.2 (Applied Biosystems ® , Foster City, CA). - -
Determinación del porcentaje de alelos tartamudos y de la intensidad relativa de picos heterocigotos. Determination of the percentage of stuttering alleles and the relative intensity of heterozygous peaks.
Durante el proceso de PCR, se va a producir el deslizamiento de la ADN polimerasa (en inglés, strand slippage) que va a generar lo que se denominan bandas tartamudas, que son productos alélicos que se diferencian del alelo verdadero tan solo en una unidad de repetición. La determinación de alelos tartamudos tanto en individuos homocigotos como heterocigotos que diferían en tamaño en más de 4 pb se efectuó calculando el porcentaje de la altura del pico del alelo tartamudo respecto a la altura del pico real. El cálculo de la intensidad relativa de picos heterocigotos (del inglés "Peak Height Ratio" ó PHR) se realizó dividiendo la altura del menor de los picos entre la altura del mayor de los heterocigotos de cada locus.  During the PCR process, the DNA polymerase slippage will occur (in English, strand slippage) that will generate what are called stuttering bands, which are allelic products that differ from the true allele only in a unit of repetition. The determination of stuttering alleles in both homozygous and heterozygous individuals that differed in size by more than 4 bp was made by calculating the percentage of the stutter allele's height relative to the actual peak's height. The calculation of the relative intensity of heterozygous peaks ("Peak Height Ratio" or PHR) was done by dividing the height of the smallest of the peaks by the height of the largest of the heterozygotes of each locus.
Sensibilidad Sensitivity
Con el fin de determinar la sensibilidad de miniX, se analizó por duplicado el ADN control 562 (Promega® Corporation, USA). Se utilizaron concentraciones de ADN de 1 ng, 500 pg, 200 pg, 100 pg, 75pg, 62,5 pg, 50 pg, 25 pg, 20 pg, 10 pg y 5pg. In order to determine the sensitivity of miniX, control DNA 562 was analyzed in duplicate (Promega ® Corporation, USA). DNA concentrations of 1 ng, 500 pg, 200 pg, 100 pg, 75pg, 62.5 pg, 50 pg, 25 pg, 20 pg, 10 pg and 5pg were used.
RESULTADOS RESULTS
Determinación del porcentaje de alelos tartamudos y de la intensidad relativa de picos heterocigotos.  Determination of the percentage of stuttering alleles and the relative intensity of heterozygous peaks.
Los picos correspondientes a alelos tartamudos, resultado del deslizamiento de la polimerasa habitualmente se traducen en un pico 4 pb menor que el alelo real. Los resultados para cada locus tras el análisis de 439 individuos de origen caucasoide correspondientes a miniX, se recogen en la Tabla 8. El valor medio de porcentaje más bajo fue observado en el locus DXS6801 (4.95Ü .82), y el valor más alto en DXS6809 ( 1 1.64±2.70).  The peaks corresponding to stuttering alleles, the result of polymerase slippage usually result in a peak 4 bp less than the real allele. The results for each locus after the analysis of 439 individuals of caucasoid origin corresponding to miniX, are shown in Table 8. The lowest average percentage value was observed in locus DXS6801 (4.95Ü .82), and the highest value in DXS6809 (1 1.64 ± 2.70).
En todos los loci se observó que cuanto mayor era el número de repeticiones de sus alelos mayor era el porcentaje de alelos tartamudos. In all loci it was observed that the higher the number of repetitions of their alleles, the greater the percentage of stuttered alleles.
Tabla 8: Porcentaje de alelos tartamudos (%) de loci STRs analizados con miniX Table 8: Percentage of stuttering alleles (%) of STR loci analyzed with miniX
Tamaño Desviación ... . ... .  Deviation Size ... ...
^ , Media Mediana „ . Mintmo Máxime muestral est ndar ^ , Medium Medium „. Maximum standard sample standard
DXS6799 405 6^1 5Ü9 2^ Τ Ϊ4 18,33  DXS6799 405 6 ^ 1 5Ü9 2 ^ Τ Ϊ4 18.33
DXS10074 494 5, 16 4,82 2,74 0,49 18, 18  DXS10074 494 5, 16 4.82 2.74 0.49 18, 18
DXS6789 416 10,52 10,1 5 2,24 2,44 18,50  DXS6789 416 10.52 10.1 5 2.24 2.44 18.50
DXS6809 436 1 1 ,64 11 ,21 2,70 4,55 22,10  DXS6809 436 1 1, 64 11, 21 2.70 4.55 22.10
DXS7132 423 7,98 7,88 2,55 1 ,22 17,91  DXS7132 423 7.98 7.88 2.55 1, 22 17.91
DXS6801 408 4,95 4,65 1 ,82 0,49 13,36 - DXS6801 408 4.95 4.65 1, 82 0.49 13.36 -
DXS10075 396 8,19 7,69 2,99 2,02 17,87 DXS10075 396 8.19 7.69 2.99 2.02 17.87
DXS10079 465 7,20 6,82 2,48 0,61 19,81  DXS10079 465 7.20 6.82 2.48 0.61 19.81
El cálculo de la Altura Relativa entre Picos (PHR) ofreció bajos valores de desviación estándar así como valores de mediana cercanos a la media en cada uno de los loci analizados mediante miniX en 439 individuos (Tabla 9), De modo que los valores registrados se encuentran en un rango comprendido entre 77-83%, los valores más bajos y más altos fueron observados en el locus DXS6809 (77.59±13.79) y en el locus DXS 10075 (83.08Ü0.14) respectivamente. Por lo que se puede concluir que en general, miniX presenta un buen balance de los alelos en heterocigosis. The calculation of the Relative Height between Peaks (PHR) offered low standard deviation values as well as median values close to the average in each of the loci analyzed by miniX in 439 individuals (Table 9), so that the recorded values are found in a range between 77-83%, the lowest and highest values were observed in the DXS6809 locus (77.59 ± 13.79) and in the DXS 10075 locus (83.08Ü0.14) respectively. So it can be concluded that in general, miniX has a good balance of alleles in heterozygosis.
Tabla 9: Intensidad relativa entre picos para cada locus STR analizado con miniX Table 9: Relative peak intensity for each STR locus analyzed with miniX
Tamaño Desviación  Deviation Size
Media Mediana Mínimo Máximo muestral estándar  Mean Median Minimum Maximum standard sample
DXS6799 25 81 ,97 84 ,85 11 ,03 56,39 99,69  DXS6799 25 81, 97 84, 85 11, 03 56.39 99.69
DXS 10074 91 78,36 79,72 13,04 42,86 99,79  DXS 10074 91 78.36 79.72 13.04 42.86 99.79
DXS6789 48 82,40 83,67 10,89 59,42 99,76  DXS6789 48 82.40 83.67 10.89 59.42 99.76
DXS6809 58 77,59 77,44 13,79 48,02 99,62  DXS6809 58 77.59 77.44 13.79 48.02 99.62
DXS7132 50 81 ,47 82,28 12,64 55,73 98,75  DXS7132 50 81, 47 82.28 12.64 55.73 98.75
DXS6801 29 81 ,48 81 ,66 11 ,63 58,93 97,87  DXS6801 29 81, 48 81, 66 11, 63 58.93 97.87
DXS10075 29 83,08 85,65 10 ,14 57 ,94 94,72  DXS10075 29 83.08 85.65 10, 14 57, 94 94.72
DXS10079 77 81 ,75 82,41 12,97 53,18 99,86  DXS10079 77 81, 75 82.41 12.97 53.18 99.86
Sensibilidad Sensitivity
La menor cantidad de ADN que permitió obtener perfiles completos mediante el análisis de miniX por duplicado fue 20 pg. Incluso cantidades de ADN en el rango de 10 a 20 pg, permitieron el análisis de 5 loci STR (un núcleo fijo de 4 loci STRs: DXS6799, DXS6789, DXS6809 y DXS 10079; y DXS 10075 ó DXS 10074, en función de la réplica) mediante alelos cuya intensidad estuvo comprendida en el rango 42-466 RFUs. Mientras que los 2 loci STR restantes (DXS7132, DXS6801 ) presentaron pérdidas alélicas por efectos estocásticos o bien no ofrecieron resultados a más de 40 RFUs en ninguno de los duplicados. Estudio comparativo de las estrategias de diseño de los conjuntos de cebadores de la presente invención respecto a los métodos del estado de la técnica  The least amount of DNA that allowed to obtain complete profiles by duplicate miniX analysis was 20 pg. Even amounts of DNA in the range of 10 to 20 pg, allowed the analysis of 5 STR loci (a fixed core of 4 STRs loci: DXS6799, DXS6789, DXS6809 and DXS 10079; and DXS 10075 or DXS 10074, depending on the replica ) by alleles whose intensity was in the range 42-466 RFUs. While the remaining 2 STR loci (DXS7132, DXS6801) presented allelic losses due to stochastic effects or did not offer results at more than 40 RFUs in any of the duplicates. Comparative study of the design strategies of the primer sets of the present invention with respect to prior art methods
Como ya se ha explicado en el apartado dedicado a los antecedentes de la invención, el tamaño de los amplicones de un sistema STR multiplex, es crítico para la obtención de - - As explained in the section dedicated to the background of the invention, the size of the amplicons of a multiplex STR system is critical for obtaining - -
perfiles genéticos a partir de muestras biológicas altamente degradadas (Butler el al., 2003 J. Forensic Sci. 48(5): 1054-64; Coble., 2005. J. Forensic Sci. 50(1): 43-53). Genetic profiles from highly degraded biological samples (Butler al., 2003 J. Forensic Sci. 48 (5): 1054-64; Coble., 2005. J. Forensic Sci. 50 (1): 43-53).
A este respecto, en la tabla 10, se comparan las estrategias de diseño de las principales reacciones multiplex del estado de la técnica y de la reacción objeto de invención (miniX), mediante loci STRs incluidos en el siguiente conjunto: DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 y DXS 10079. Se incluyen los rangos alélicos de las principales muestras poblacionales analizadas hasta la fecha. In this regard, in Table 10, the design strategies of the main multiplex reactions of the state of the art and of the reaction object of the invention (miniX) are compared, using STRs loci included in the following set: DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 and DXS 10079. The allelic ranges of the main population samples analyzed to date are included.
Tabla 10. Comparación del tamaño en pares de bases de loci incluidos en miniX con reacciones multiplex del estado de la técnica. Table 10. Comparison of base pair size of loci included in miniX with state-of-the-art multiplex reactions.
Figure imgf000045_0001
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Figure imgf000046_0001
Figure imgf000045_0001
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Figure imgf000046_0001
Por otro lado, en la tabla 1 1 se detalla el poder de discriminación obtenido mediante miniX, Decaplex y Sextaplex, tras el análisis de los loci compartidos entre miniX y dichas reacciones, a partir de fragmentos de ADN altamente degradados: miniX vs. Decaplex (DXS6789, DXS6809 y DXS7132); y miniX vs. sextaplex (DXS 10074, DXS6789, DXS6809, DXS6801, DXS 10075 y DXS10079). Los valores obtenidos corresponden al análisis de fragmentos de ADN de 220 pb. Los resultados muestran que, a partir de extractos de ADN altamente fragmentados (<220pb) miniX alcanza un mayor PD en el análisis de los loci compartidos con Decaplex (DXS6789, DXS6809 y DXS7132) y aquellos compartidos con Sextaplex (DXS10074, DXS6789, DXS6809, DXS6801, DXS 10075 y DXS 10079), tanto en hombres como en mujeres. On the other hand, in table 1 1 the discrimination power obtained by miniX, Decaplex and Sextaplex is detailed, after the analysis of the loci shared between miniX and said reactions, from highly degraded DNA fragments: miniX vs. Decaplex (DXS6789, DXS6809 and DXS7132); and miniX vs. sextaplex (DXS 10074, DXS6789, DXS6809, DXS6801, DXS 10075 and DXS10079). The values obtained correspond to the analysis of DNA fragments of 220 bp. The results show that, from highly fragmented DNA extracts (<220pb) miniX achieves a higher PD in the analysis of loci shared with Decaplex (DXS6789, DXS6809 and DXS7132) and those shared with Sextaplex (DXS10074, DXS6789, DXS6809, DXS6801, DXS 10075 and DXS 10079), both in men and women.
Tabla 11. Comparación del Poder de discriminación (PD) obtenido mediante: la reacción multiplex objeto de la invención (miniX), así como mediante Decaplex (Gusmáo et al., 2009) y Sextaplex (Castañeda et al., 2012), principales reacciones del estado de la técnica que analizan loci STRs del conjunto DXS6799, DXSI 0074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 y DXS10079. Los resultados corresponden al PD calculado en hombres y mujeres, tras el análisis de los loci STRs cuyo tamaño no sea superior a las 220 pb, Table 11. Comparison of the Power of discrimination (PD) obtained by: the multiplex reaction object of the invention (miniX), as well as by Decaplex (Gusmáo et al., 2009) and Sextaplex (Castañeda et al., 2012), main reactions of the prior art analyzing STRs loci of the DXS6799, DXSI 0074, DXS6789, DXS6809, DXS7132, DXS6801, DXS10075 and DXS10079. The results correspond to the PD calculated in men and women, after the analysis of the STRs loci whose size does not exceed 220 bp,
Figure imgf000046_0002
Figure imgf000046_0002
Estudio comparativo de la capacidad de análisis de muestras de ADN altamente degradadas de los conjuntos de cebadores de la presente invención respecto a los métodos del estado de la técnica. - - Comparative study of the ability to analyze highly degraded DNA samples of the primer sets of the present invention with respect to prior art methods. - -
La comparación de la capacidad de análisis de muestras altamente degradadas del sistema objeto de la invención respecto a las principales reacciones del estado de la técnica, Decaplex (Figura 3) y Sextaplex (Figura 4), se realizó mediante el análisis por las 3 reacciones multiplexes, de 24 muestras de ADN procedentes de tejidos incluidos en parafma. Este tipo de muestras se caracteriza por una fragmentación generalizada del ADN. The comparison of the analysis capacity of highly degraded samples of the system object of the invention with respect to the main reactions of the state of the art, Decaplex (Figure 3) and Sextaplex (Figure 4), was performed by analysis by the 3 multiplex reactions , of 24 DNA samples from tissues included in parafma. This type of samples is characterized by a generalized DNA fragmentation.
La intensidad de la señal de un alelo se relaciona con la Habilidad de la misma, de modo que habitualmente no se realizan genotipados basados en alelos cuya altura no supere las 50-100 RFUs (Relative Units of Fluorescence). Es por ello que se ha evaluado el rendimiento en el análisis de muestras de ADN altamente fragmentadas en base a dos variables: A) el porcentaje de muestras en el que se ha logrado genotipar cada STR, descartando aquellos alelos de altura inferior a 50 RFUs; y B) el porcentaje de muestras en el que el genotipado corresponde a alelos de altura superior a 200 RFUs, indicando una fíabilidad extra del resultado. The intensity of the signal of an allele is related to its ability, so that genotyping based on alleles whose height does not exceed 50-100 RFUs (Relative Units of Fluorescence) is usually not performed. That is why the performance in the analysis of highly fragmented DNA samples has been evaluated based on two variables: A) the percentage of samples in which each STR has been genotyped, discarding those alleles of height less than 50 RFUs; and B) the percentage of samples in which the genotyping corresponds to alleles of height greater than 200 RFUs, indicating extra reliability of the result.
Sólo se han considerado como STRs analizados con éxito, aquellos en los que se lograba genotipar la totalidad de los alelos presentes en esa muestra. Al no disponer de muestras de referencia se ha tomado como análisis completo de un STR aquellos casos en los que se ha logrado obtener dos alelos para una misma muestra o cuando en todos los resultados obtenidos mediante las diferentes reacciones se ha detectado un único alelo. Only those that were able to genotype all alleles present in that sample have been considered as STRs successfully analyzed. In the absence of reference samples, a complete analysis of a STR has been taken in those cases in which two alleles have been obtained for the same sample or when in all the results obtained through the different reactions a single allele has been detected.
Tal y como se observa en la figura 3, miniX presenta un mayor rendimiento global que Decaplex en 2 de los 3 loci compartidos, con la excepción del locus DXS7132, que ha sido genotipado mediante Decaplex en el 92% de las muestras respecto a un 88% en el caso de miniX. Si bien, en este locus, dicho 4% de diferencia corresponde a alelos cuya altura no supera las 200 RFUs. Por otro lado, miniX muestra un rendimiento global superior a Sextaplex en los 6 loci STR compartidos y un mayor porcentaje de alelos por encima de las 200 RFUs (Figura 4). As shown in Figure 3, miniX has a higher overall performance than Decaplex in 2 of the 3 shared loci, with the exception of the DXS7132 locus, which has been genotyped by Decaplex in 92% of the samples compared to 88 % in the case of miniX. Although, in this locus, said 4% difference corresponds to alleles whose height does not exceed 200 RFUs. On the other hand, miniX shows a global performance superior to Sextaplex in the 6 shared STR loci and a higher percentage of alleles above 200 RFUs (Figure 4).
DISCUSION - - DISCUSSION - -
A continuación se discuten los resultados relativos a la validación de miniX, en los ensayos de determinación del porcentaje de alelos tartamudos, intensidad relativa de picos heterocigotos (PHR) y sensibilidad. Así mismo se discuten los resultados obtenidos en los estudios comparativos del método de la invención y de los métodos del estado de la técnica, tanto respecto a la estrategia de diseño como respecto a la capacidad de análisis de los loci STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079 a partir de muestras de ADN altamente degradadas. The results related to the validation of miniX are discussed below, in the tests for determining the percentage of stuttering alleles, relative intensity of heterozygous peaks (PHR) and sensitivity. Likewise, the results obtained in the comparative studies of the method of the invention and the methods of the prior art are discussed, both with respect to the design strategy and with respect to the analysis capacity of the loci STRs DXS6799, DXS 10074, DXS6789 , DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 from highly degraded DNA samples.
La estimación de la capacidad analítica de un sistema multiplex requiere valorar su sensibilidad. Del mismo modo, es necesario evaluar los resultados obtenidos para porcentaje de alelos tartamudos y PHR (Budowle et al., 2009 J. Forensic Sci. 54(4): 810-821 ). Esto es debido a que un porcentaje de alelos tartamudos elevado puede conducir a equívocos en la interpretación de alelos de intensidad reducida (Walsh et al., 1996 Nucleic Acids. Re. 24( 14): 2807-2812). Los valores porcentaje de alelos tartamudos de media, mediana, desviación estándar, valores mínimos y máximos del método de la invención, se ajustan a los obtenidos por otros grupos de investigación en la validación de otros sistemas de análisis de loci STRs del Cromosoma X (Asamura et al., 2006 Int. J. Legal Med. 120: 174- 181 , en la validación de otras reacciones multiplex de STRs autosómicos tales como I-DNA- 1 (Odriozola et al., 201 1 Int. J. Legal Med. 125(5):685-94), I-DNA-2 (Odriozola et al., 2012 Int. J. Legal Med. 126( 1 ): 167-72) y genRESMPX-3 (Schlenk et al, 2004. Int J Legal Med, 1 18( 1 ): 55-61). En conjunto, los bajos porcentajes de alelos tartamudos obtenidos para miniX favorecen el correcto genotípado de las muestras. The estimation of the analytical capacity of a multiplex system requires assessing its sensitivity. In the same way, it is necessary to evaluate the results obtained for percentage of stuttering alleles and PHR (Budowle et al., 2009 J. Forensic Sci. 54 (4): 810-821). This is because a high percentage of stuttering alleles can lead to misunderstandings in the interpretation of alleles of reduced intensity (Walsh et al., 1996 Nucleic Acids. Re. 24 (14): 2807-2812). The percentage values of stuttering alleles of mean, median, standard deviation, minimum and maximum values of the method of the invention, are adjusted to those obtained by other research groups in the validation of other STRs loci analysis systems of Chromosome X (Asamura et al., 2006 Int. J. Legal Med. 120: 174-181, in the validation of other multiplex reactions of autosomal STRs such as I-DNA-1 (Odriozola et al., 201 1 Int. J. Legal Med. 125 (5): 685-94), I-DNA-2 (Odriozola et al., 2012 Int. J. Legal Med. 126 (1): 167-72) and geneRESMPX-3 (Schlenk et al, 2004. Int J Legal Med, 1 18 (1): 55-61) Together, the low percentages of stuttering alleles obtained for miniX favor the correct genotyping of the samples.
Por otro lado los valores de PHR definen el balance existente en la amplificación de heterocigotos. Para miniX se observa una PHR media inferior a la reportada para otros sistemas de identificación tales como I-DNA-1 (Odriozola et al., 201 1 Int. J. Legal Med. 125(5):685-94), I-DNA-2 (Odriozola et al., 2012 Int. J. Legal Med. 126( 1): 167-72), genRESMPX-3 (Schlenk et al, 2004. Int J Legal Med, 1 18( 1): 55-61 ), MiniFiler™ PCR Amplification Kit (Mulero et al., 2008. J. Forensic Sci. 53 (4): 838-852) e Identifiler® Direct PCR Amplification Kit (Wang et al., 201 1 J. Forensic. Sci. 56 (4) 835: 845). . Esta diferencia podría deberse a que miniX analiza loci STRs diferentes a las otras dos reacciones, cuya estructura repetitiva difiere. En cualquier caso, para miniX se observa una PHR media superior al 80 %, lo que supone un elevado balance entre heterocigotos. En cuanto a la - - On the other hand, the PHR values define the balance in the heterozygous amplification. For miniX, a lower average PHR is observed than that reported for other identification systems such as I-DNA-1 (Odriozola et al., 201 1 Int. J. Legal Med. 125 (5): 685-94), I- DNA-2 (Odriozola et al., 2012 Int. J. Legal Med. 126 (1): 167-72), geneRESMPX-3 (Schlenk et al, 2004. Int J Legal Med, 1 18 (1): 55- 61), MiniFiler ™ PCR Amplification Kit (Mulero et al., 2008. J. Forensic Sci. 53 (4): 838-852) and Identifiler® Direct PCR Amplification Kit (Wang et al., 201 1 J. Forensic. Sci 56 (4) 835: 845). . This difference could be due to the fact that miniX analyzes different STR loci than the other two reactions, whose repetitive structure differs. In any case, for miniX an average PHR of more than 80% is observed, which implies a high balance between heterozygotes. Refering to - -
homogeneidad de PHR en los diferentes loci, miniX muestra una menor desviación media estándar que la reportada para Minifíler™ Kit PCR (Applied Biosystems, Foster City, CA) (12,02 frente a 33,47) (Mulero et al., 2008 J. Forensic Sci. 53(4): 838-52). No ha sido posible la comparación del porcentaje de alelos tartamudos y PHR con reacciones que incluyan los loci STRs de la reacción objeto de invención, tales como Decaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 (3):227- 234) y Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57(1): 192-195) debido a la ausencia en el estado de la técnica de estudios que revelen estos datos. La sensibilidad de una STR multiplex es determinante en la obtención de perfiles de STRs con suficiente poder de discriminación (Budowle et al., 2009. Croat. Med. J. 50(3): 207-17). Por ello en la presente invención, se han perseguido aquellas condiciones experimentales en las que miniX ofrece una alta sensibilidad, permitiendo el análisis de los 8 loci STRs incluidos a partir de cantidades de 20 pg. MiniX incluso posibilita el análisis de 5 loci STR (un núcleo fijo de 4 loci STRs: DXS6799, DXS6789, DXS6809 y DXS 10079; y DXS 10075 ó DXS 10074, en función de la réplica) en muestras con cantidades de ADN en el rango de 10 a 20 pg. PHR homogeneity in the different loci, miniX shows a lower standard mean deviation than the one reported for Minificaler ™ PCR Kit (Applied Biosystems, Foster City, CA) (12.02 vs. 33.47) (Mulero et al., 2008 J Forensic Sci. 53 (4): 838-52). It has not been possible to compare the percentage of stuttering alleles and PHR with reactions that include the STR loci of the reaction object of the invention, such as Decaplex (Gusmao et al., 2009 Int. J. Legal Med. 123 (3): 227 - 234) and Sextaplex (Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195) due to the absence in the state of the art of studies that reveal these data. The sensitivity of a multiplex STR is decisive in obtaining STR profiles with sufficient discriminating power (Budowle et al., 2009. Croat. Med. J. 50 (3): 207-17). Therefore, in the present invention, those experimental conditions in which miniX offers high sensitivity have been pursued, allowing the analysis of the 8 STR loci included from amounts of 20 pg. MiniX even enables the analysis of 5 STR loci (a fixed core of 4 STRs loci: DXS6799, DXS6789, DXS6809 and DXS 10079; and DXS 10075 or DXS 10074, depending on the replica) in samples with amounts of DNA in the range of 10 to 20 pg.
Se ha comparado la sensibilidad de miniX con la reportada para otros sistemas de análisis de loci STRs y más específicamente para aquellos que incluyen miniSTR del cromosoma X. The sensitivity of miniX has been compared with that reported for other STRs loci analysis systems and more specifically for those that include XS miniSTRs.
PowerPlexló system y PowerPlex® 16 HS system (Promega® Corporation, USA), así como Identifiler® (Applied Biosystems, Foster City, CA), requieren cantidades mayores de ADN molde que miniX, (respectivamente 250, 62,5 y 250 pg) (Collins et al., 2004. J. Forensic Sci. 49(6): 1265-1277; renke et al., 2002 J. Forensic Sci. 47(4): 773-785). It powerplexló system and PowerPlex ® 16 HS system (Promega® Corporation, USA) and Identifiler ® (Applied Biosystems, Foster City, CA), require larger amounts of template DNA Minix (respectively 250, 62.5 and 250 pg) (Collins et al., 2004. J. Forensic Sci. 49 (6): 1265-1277; renke et al., 2002 J. Forensic Sci. 47 (4): 773-785).
Otros sistemas multiplex de amplia utilización son genRESMPX-3 (Serac, Homburg, Germany), AmpFISTR Profiler Plus y AmpFISTR Cofiler multiplex Systems (Applied Biosystems, Foster City, CA), que también requieren de cantidades mayores de ADN molde que miniX , 120 pg el primero (Schlenk et al., 2004 Int. J. Legal Med 1 18(1): 55-61) y 160 pg el segundo y el tercero (LaFountain et al., 2001. J. Forensic Sci. 46: 49). - - Other widely used multiplex systems are genRESMPX-3 (Serac, Homburg, Germany), AmpFISTR Profiler Plus and AmpFISTR Cofiler multiplex Systems (Applied Biosystems, Foster City, CA), which also require larger amounts of template DNA than miniX, 120 pg the first (Schlenk et al., 2004 Int. J. Legal Med 1 18 (1): 55-61) and 160 pg the second and third (LaFountain et al., 2001. J. Forensic Sci. 46: 49) . - -
En cuanto a la comparación de la sensibilidad de miniX con reacciones que analicen miniSTRs del cromosoma X, si bien estas reacciones permite el estudio de diferentes loci a los incluidos en miniX (Tabla 3), cabe señalar que la sensibilidad de Mini X y reacciones a, y b (Asamura et al., 2006 Int. J. Legal Med. 120: 174-181) es similar, habiéndose amplificado la totalidad de los loci incluidos en cada una de las reacciones a partir de cantidades superiores a 20 pg. En cambio, las reacciones c y d (Diegoli et Coble., 2010, Forensic Sci. Int. Genet. 5(5) 415- 421) requiere cantidades superiores a MiniX, al menos 200 pg de ADN molde para obtener perfiles completos, y 100 pg para perfiles con pérdida de 1 -2 marcadores. Los extractos de ADN analizados en laboratorios forenses se caracterizan frecuentemente por contener cantidades muy reducidas de ADN, lo que dificulta la obtención de perfiles genéticos de elevado poder de discriminación tras su análisis mediante un sistema STR multiplex. El tamaño de los amplicones de un sistema STR multiplex es crítico para la obtención de perfiles genéticos a partir de muestras biológicas altamente degradadas (Budowle et al. ,2009 Croat. Med. J. 50(3): 207-17). MiniX, destaca por ser el único sistema disponible en la actualidad que permite analizar la totalidad de los loci STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS10079, en una única reacción multiplex, incluyendo además, amplificados de menor tamaño que los disponibles en el estado de la técnica en 6 de los 8 loci STRs incluidos (Tabla 10). La excepción la constituyen los locus DXS 10074 y DXS6801 que da lugar a amplificados 27 y 37 pb mayores que los obtenidos mediante las reacciones desarrolladas por Becker et. al, 2008 Forensic. Sci. Int. Genet. 2(1): 69-74 y Castañeda et al., 2012 J. Forensic Sci. 57( 1): 192- 195, respectivamente. También cabe señalar que, mediante miniX se producen los amplificados de menor tamaño posible para el locus DXS6809 (175-219 pb), al haber sido diseñados en la zona directamente adyacente a la región repetitiva de dicho locus. El resto de loci STRs dan lugar a amplificados menores de 200 pb. Así mismo, miniX representa la única alternativa en formato miniSTR para la amplificación de los loci DXS6799, DXS 10075 y DXS 10079. - - Regarding the comparison of the sensitivity of miniX with reactions that analyze miniSTRs on the X chromosome, although these reactions allow the study of different loci to those included in miniX (Table 3), it should be noted that the sensitivity of Mini X and reactions to , and b (Asamura et al., 2006 Int. J. Legal Med. 120: 174-181) is similar, all the loci included in each of the reactions having been amplified from amounts greater than 20 pg. In contrast, cyd reactions (Diegoli et Coble., 2010, Forensic Sci. Int. Genet. 5 (5) 415-421) require amounts greater than MiniX, at least 200 pg of template DNA to obtain complete profiles, and 100 pg for profiles with loss of 1-2 markers. DNA extracts analyzed in forensic laboratories are often characterized by containing very small amounts of DNA, which makes it difficult to obtain genetic profiles of high discriminatory power after analysis using a multiplex STR system. The size of the amplicons of a STR multiplex system is critical for obtaining genetic profiles from highly degraded biological samples (Budowle et al., 2009 Croat. Med. J. 50 (3): 207-17). MiniX, stands out for being the only system currently available that allows analyzing all the STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS10079 loci, in a single multiplex reaction, also including amplified smaller than those available in the state of the art in 6 of the 8 STR loci included (Table 10). The exception is the DXS 10074 and DXS6801 locus that results in amplifications 27 and 37 bp greater than those obtained by the reactions developed by Becker et. al, 2008 Forensic. Sci. Int. Genet. 2 (1): 69-74 and Castañeda et al., 2012 J. Forensic Sci. 57 (1): 192-195, respectively. It should also be noted that, through miniX, the smallest possible amplifications are produced for the DXS6809 locus (175-219 bp), having been designed in the area directly adjacent to the repetitive region of said locus. The rest of the STRs loci give rise to amplitudes less than 200 bp. Likewise, miniX represents the only alternative in miniSTR format for the amplification of the DXS6799, DXS 10075 and DXS 10079 loci. - -
Por otro lado, el mayor poder de discriminación obtenido mediante miniX respecto a decaplex y sextaplex, a partir de fragmentos de ADN que no excedan las 220 pb, pone de manifiesto la superioridad de su diseño de miniX (Tabla 1 1). El análisis comparativo de la capacidad de análisis de muestras de ADN altamente degradadas, consistió en el análisis de muestras de parafína caracterizadas por la elevada fragmentación de su ADN, mediante: miniX, Decaplex y Sextaplex. miniX alcanzó un rendimiento mayor que Decaplex en dos de los 3 loci compartidos. Mientras que en el locus DXS7132, ambas reacciones obtuvieron un rendimiento del 88 % mediante señales que superaron las 200 RFUs y Decaplex obtuvo un 4% adicional mediante señales que no alcanzaron dicha intensidad. Por otro lado, miniX superó el rendimiento obtenido mediante Sextaplex en los 6 loci STRs compartidos por ambas reacciones. On the other hand, the greater discrimination power obtained through miniX with respect to decaplex and sextaplex, from DNA fragments that do not exceed 220 bp, shows the superiority of its miniX design (Table 1 1). The comparative analysis of the ability to analyze highly degraded DNA samples consisted of the analysis of paraffin samples characterized by the high fragmentation of their DNA, using: miniX, Decaplex and Sextaplex. miniX achieved greater performance than Decaplex in two of the 3 shared loci. While in the DXS7132 locus, both reactions obtained a yield of 88% by means of signals that exceeded 200 RFUs and Decaplex obtained an additional 4% by means of signals that did not reach said intensity. On the other hand, miniX exceeded the performance obtained through Sextaplex in the 6 STR loci shared by both reactions.
En síntesis, la presente validación incluye tanto los ensayos de alelos tartamudos, PHR y sensibilidad, como estudios comparativos de estrategias de diseño y de análisis de muestras de ADN altamente degradadas. Los resultados obtenidos demuestran que el rendimiento de la presente invención en el análisis a partir de muestras de ADN altamente degradadas y/o escasas de los loci STRs DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079, es superior al de los métodos del estado de la técnica. In summary, this validation includes both stuttering alleles, PHR and sensitivity assays, as well as comparative studies of design strategies and analysis of highly degraded DNA samples. The results obtained demonstrate that the performance of the present invention in the analysis from highly degraded and / or scarce DNA samples of the DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079 loci is superior to the prior art methods.

Claims

REIVINDICACIONES
1) Un método para obtener el perfil genético completo de un individuo que comprende el análisis, en un extracto de ADN procedente de dicho individuo mediante una única reacción de amplificación multiplex, de la combinación de 8 loci STRs del cromosoma X constituidos por DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801 , DXS 10075 y DXS 10079, donde la pareja de cebadores empleada en la reacción de amplificación multiplex específica para cada uno de los 8 loci STR analizados es la pareja de oligonucléotidos mostrada en las secuencias 1) A method to obtain the complete genetic profile of an individual comprising the analysis, in a DNA extract from said individual by means of a single multiplex amplification reaction, of the combination of 8 STRs loci of the X chromosome constituted by DXS6799, DXS 10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079, where the primer pair used in the specific multiplex amplification reaction for each of the 8 STR loci analyzed is the oligonucleotide pair shown in the sequences
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799, - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 11 y SEQ ID NO: 12 para el locus DXS6801 ,  - SEQ ID NO: 11 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO: 14 y/o SEQ ID NO: 15 para el locus DXS 10075, y  - SEQ ID NO: 13 and / or SEQ ID NO: 14 and / or SEQ ID NO: 15 for the DXS 10075 locus, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS10079.  - SEQ ID NO: 16 and SEQ ID NO: 17 for locus DXS10079.
2) Método según la reivindicación 1, en donde la temperatura de fusión de la reacción de amplificación multiplex que comprende los oligonucléotidos SEQ ID NO: 1 a SEQ ID NO: 17 está comprendida entre 57,5 y 63 °C. 2) A method according to claim 1, wherein the melting temperature of the multiplex amplification reaction comprising oligonucleotides SEQ ID NO: 1 to SEQ ID NO: 17 is between 57.5 and 63 ° C.
3) Método según la reivindicación 1 ó 2, en donde uno de los oligonucléotidos de cada pareja de cebadores está marcado en uno de sus extremos. 3) Method according to claim 1 or 2, wherein one of the oligonucleotides of each pair of primers is labeled at one of its ends.
4) Método según la reivindicación 3, en donde los compuestos empleados en el mareaje de los oligonucléotidos se seleccionan del grupo que consiste en un radioisótopo, un material fluorescente, digoxigenina y biotina. 4) Method according to claim 3, wherein the compounds employed in the oligonucleotide mapping are selected from the group consisting of a radioisotope, a fluorescent material, digoxigenin and biotin.
5) Método según la reivindicación 4, en donde el material fluorescente se selecciona del grupo que consiste en 5-carboxifluoresceína (5-FAM), 6-FAM, análogo tetraclorinado de t-FAM (TET), análogo hexaclorinado de 6-FAM (HEX), 6- carboxitetrametilrodamina (TAMRA), 6-carboxi-X-rodamina (ROX), 6-carboxi-4', 5'-dicloro-2\ 7'-dimetoxifluoresceína (JOE), NED, Cy-3, Cy-5, Cy-5.5, fluorescein-6-isotiocinato (FITC) y tetrametilrodamina-5-isotiocÍnato (TRITC). 5) Method according to claim 4, wherein the fluorescent material is selected from the group consisting of 5-carboxyfluorescein (5-FAM), 6-FAM, analog t-FAM tetrachlorinated (TET), 6-FAM hexachlorinated analog (HEX), 6- carboxytetramethylrodamine (TAMRA), 6-carboxy-X-rhodamine (ROX), 6-carboxy-4 ', 5'-dichloro-2 \ 7'-dimethoxyfluorescein (JOE), NED, Cy-3, Cy-5, Cy-5.5, fluorescein-6-isothiocinate (FITC) and tetramethylrodamine-5-isothiocyanate (TRITC).
6) Método según una cualquiera de las reivindicaciones 1 a 5, en donde el extracto de ADN procede de una muestra de sangre, pelo, saliva, epidermis, esperma, caspa, cenizas, una muestra vaginal o una muestra de tejido. 6) Method according to any one of claims 1 to 5, wherein the DNA extract is derived from a sample of blood, hair, saliva, epidermis, sperm, dandruff, ashes, a vaginal sample or a tissue sample.
7) Un kit, para llevar a cabo el método de las reivindicaciones 1-6, que comprende parejas de cebadores específicas para amplificar en una única reacción multiplex los 8 loci STRs DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS10079, donde la pareja de cebadores empleada en la reacción de amplificación multiplex específica para cada uno de los 8 loci STR analizados es la pareja de oligonucleótidos mostrada en las secuencias 7) A kit, for carrying out the method of claims 1-6, comprising pairs of specific primers to amplify in a single multiplex reaction the 8 STRs loci DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS10079, where the primer pair used in the multiplex amplification reaction specific for each of the 8 STR loci analyzed is the oligonucleotide pair shown in the sequences
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799, - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 1 1 y SEQ ID NO: 12 para el locus DXS6801,  - SEQ ID NO: 1 1 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO 14 y/o SEQ ID NO: 15 para el locus DXS 10075, y  - SEQ ID NO: 13 and / or SEQ ID NO 14 and / or SEQ ID NO: 15 for the DXS 10075 locus, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079.  - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus.
8) Kit según la reivindicación 7, en el que la pareja de cebadores comprende un oligonucleótido marcado en uno de sus extremos. 8) Kit according to claim 7, wherein the primer pair comprises an oligonucleotide labeled at one of its ends.
9) Kit según la reivindicación 7 que comprende adicionalmente los reactivos necesarios para marcar las parejas de cebadores. 10) Kit según la reivindicación 9, en donde los reactivos empleados para marcar las parejas de cebadores se seleccionan del grupo que consiste en un radioisótopo, un material fluorescente, digoxigenina y biotina. 9) Kit according to claim 7 further comprising the reagents necessary to label the primer pairs. 10) Kit according to claim 9, wherein the reagents used to label the primer pairs are selected from the group consisting of a radioisotope, a fluorescent material, digoxigenin and biotin.
11) Kit según la reivindicación 10, en donde el material fluorescente se selecciona del grupo que consiste en 5-carboxifluoresceína (5-FAM), 6-FAM, análogo tetraclorinado de t-FAM (TET), análogo hexaclorinado de 6-FAM (HEX), 6- carboxitetrametilrodamina (TAMRA), 6-carboxi-X-rodamina (ROX), 6-carboxi-4\ 5'-dicloro-2', 7'-dimetoxifluoresceína (JOE), NED, Cy-3, Cy-5, Cy-5.5, fluorescein-6-isotiocinato (FITC) y tetrametilrodamina-5-isotiocinato (TRITC). 11) Kit according to claim 10, wherein the fluorescent material is selected from the group consisting of 5-carboxyfluorescein (5-FAM), 6-FAM, t-FAM tetrachlorinated analog (TET), 6-FAM hexachlorinated analog ( HEX), 6- carboxytetramethylrodamine (TAMRA), 6-carboxy-X-rhodamine (ROX), 6-carboxy-4 \ 5'-dichloro-2 ', 7'-dimethoxyfluorescein (JOE), NED, Cy-3, Cy -5, Cy-5.5, fluorescein-6-isothiocinate (FITC) and tetramethylrodamine-5-isothiocinate (TRITC).
12) Conjunto de parejas de cebadores que comprende las siguientes 8 parejas de cebadores dirigidas a amplificar en una única reacción multiplex 8 loci STRs DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 y DXS 10079 12) Set of primer pairs comprising the following 8 primer pairs aimed at amplifying in a single multiplex reaction 8 loci STRs DXS6799, DXS10074, DXS6789, DXS6809, DXS7132, DXS6801, DXS 10075 and DXS 10079
- SEQ ID NO: 1 y SEQ ID NO: 2 para el locus DXS6799,  - SEQ ID NO: 1 and SEQ ID NO: 2 for locus DXS6799,
- SEQ ID NO: 3 y SEQ ID NO: 4 para el locus DXS 10074,  - SEQ ID NO: 3 and SEQ ID NO: 4 for locus DXS 10074,
- SEQ ID NO: 5 y SEQ ID NO: 6 para el locus DXS6789,  - SEQ ID NO: 5 and SEQ ID NO: 6 for locus DXS6789,
- SEQ ID NO: 7 y SEQ ID NO: 8 para el locus DXS6809,  - SEQ ID NO: 7 and SEQ ID NO: 8 for locus DXS6809,
- SEQ ID NO: 9 y SEQ ID NO: 10 para el locus DXS7132,  - SEQ ID NO: 9 and SEQ ID NO: 10 for locus DXS7132,
- SEQ ID NO: 11 y SEQ ID NO: 12 para el locus DXS6801,  - SEQ ID NO: 11 and SEQ ID NO: 12 for locus DXS6801,
- SEQ ID NO: 13 y/o SEQ ID NO: 14 y/o SEQ ID NO: 15 para el locus DXS 10075, y  - SEQ ID NO: 13 and / or SEQ ID NO: 14 and / or SEQ ID NO: 15 for the DXS 10075 locus, and
- SEQ ID NO: 16 y SEQ ID NO: 17 para el locus DXS 10079.  - SEQ ID NO: 16 and SEQ ID NO: 17 for the DXS 10079 locus.
13) Uso de un conjunto de parejas de cebadores según la reivindicación 12 1 para obtener el perfil genético de un individuo, para identificar un individuo, para determinar relaciones de parentesco entre individuos o para identificar restos humanos. 13) Use of a set of primer pairs according to claim 12 1 to obtain the genetic profile of an individual, to identify an individual, to determine kinship relationships between individuals or to identify human remains.
PCT/ES2013/000170 2012-07-10 2013-07-09 Method for obtaining an individual's genetic profile by means of x chromosome loci analysis WO2014009578A1 (en)

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