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WIREs Forensic Sci

Y‐chromosome short tandem repeats in forensics—Sexing, profiling, and matching male DNA

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Abstract The analysis of short tandem repeat (STR) markers located on the Y chromosome is an established method in forensic casework analysis. Usually this method is applied in cases of male‐on‐female sexual assault, in which the victim's DNA is in great excess and masked the male contribution. Y‐STR analysis is able to detect the presence of minuscule amounts of male DNA of one or multiple donors and resulting genetic profiles can be compared to known reference samples. The expert has to determine whether the Y‐STR result of a trace is suitable for a biostatistical calculation in case of a match. The Discrete Laplace method which is implemented in the Y chromosome haplotype reference database (YHRD) can be used to estimate haplotype frequencies with a better approximation than other methods namely the counting method. Moreover, Y‐SNPs in combination with Y‐STRs can infer the biogeographical origin of an unknown male person with comparably high precision due to the availability of a robust phylogenetic tree and large reference data collections. Y‐based ancestry prediction and familial searching can, therefore, provide important investigative leads in crime cases without suspect. This article is categorized under: Forensic Biology > Haploid Markers Forensic Biology > Ancestry Determination using DNA Methods Forensic Biology > DNA Databases and Biometrics Forensic Biology > Forensic DNA Technologies
YHRD report for a 17‐loci Y‐STR profile extracted from a female/male mixed DNA trace described in the text. Observations, augmented counts (in the formula “n” depicts the observations and “N” the database size, the haplotype in question is added to both numerator and denominator resulting in a conservative “augmented” count estimate) and DL estimates are given for different metapopulations. The count and the extrapolated DL values are in the same order of magnitude only for Western Europeans (depicted in red color), but become clearly divergent for Asian and African reference databases which are dominated by different founder lineages. The analyzed haplotype is blinded
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Polyacrylamide vertical slab gel using a sequenced DNA as length standard (four lanes to the left). Autosomal length alleles at STR locus D12S66 and Y‐STR alleles at locus DYS19 were detected in a vaginal swab (St) and reference DNA samples of suspect (Su) and victim (Vi). Alleles are marked by arrows. M1‐4 depict DYS19 reference alleles
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Comparison of observed and DL‐estimated frequencies of all 15‐loci haplotypes in the Western European metapopulation (YHRD, release 55, N = 25,665 YFiler haplotypes excluding the multicopy locus DYS385ab). The red line depicts concordance between observed and estimated haplotype frequencies; the green line marks the threshold of the DL frequency estimation for very rare haplotypes in this MP which is based on the distribution of singletons frequency estimates. To the left, the density distribution of the singleton estimates is plotted (modified from Roewer & Willuweit, )
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Growth of YHRD between 1999 to 2018 (Release 1 to 59)
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Schematic representation of a Y‐STR cluster and its evolution from an ancestral haplotype (modified from Jobling & Tyler‐Smith, )
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Browse by Topic

Forensic Biology > Ancestry Determination using DNA Methods
Forensic Biology > DNA Databases and Biometrics
Forensic Biology > Haploid Markers
Forensic Biology > Forensic DNA Technologies

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