Differential pattern of genetic variability at the DXYS156 locus on homologous regions of X and Y chromosomes in Indian population and its forensic implications

Abstract

Sex determination is routinely performed in forensic casework using the amelogenin-based sex test. The human amelogenin gene resides on homologous regions of the sex chromosomes. However, a deletion in the AmelY locus may sometimes lead to gender misidentification. The pentanucleotide microsatellite DXYS156 maps to the pseudoautosomal region of both the sex chromosomes and helps in sex determination. This STR offers an advantage of being multi-allelic, with delimited and demographically restricted alleles for the X and Y chromosomes. Also, the Y-specific alleles can be discerned from their X chromosomal counterpart due to an adenine insertion in the (TAAAA)(n) repeat units of the STR. The present study examines the differential variation pattern at the X and Y locus of this STR in unrelated males from linguistically and geographically diverse populations of India. The study also attempts to undertake a comparison between the two sex-determining markers through validation studies. Two population samples and few validation samples which showed erroneous results for the amelogenin locus produced alleles specific to each of the sex chromosomes at the DXYS156 locus. The error rate for the amelogenin locus was observed to be 0.27% in case of the population samples and 0.5% in case of validation samples. Statistical parameters of forensic interest indicate that the DXYS156 locus is polymorphic and discriminating for the Indian population.

A Study on Deletion in Polymer Region of Amelogenin (Amel Y) Gene: Significant Importance in Sex Determination and Identification of Sexual Assault Perpetrator

“…The male DNA component could be detected from mixed samples using this approach with a male: female ratio as low as 1:10 and a detection limit of 63 pg of genomic DNA. [42,43] Additionally, sex can be determined using the pentanucleotide microsatellite DXYS156, which maps to the pseudo-autosomal region of both sex chromosomes. The multi-allelic STR DXYS156 has an allelic distribution that is geographically distinctive, making it useful for determining an individual's sex as well as their likely place of origin.…”

“…The male DNA component could be detected from mixed samples using this approach with a male: female ratio as low as 1:10 and a detection limit of 63 pg of genomic DNA. [ 42,43 ] Additionally, sex can be determined using the pentanucleotide microsatellite…”

Molecular analysis for sex determination in forensic dentistry: a systematic review

“…DNA is the most reliable source with high accuracy in sex determination when compared to other non-metric and metric measurements (Capitaneanu et al 2017a). The molecular indicators for forensic sex determination, based on PCR analysis, included amelogenin, SRY, DXYS156, and TSPY (Butler and Li 2014;Mukerjee et al 2013).…”