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127 Int'l J. Legal Med. 1 (2013)

handle is hein.journals/injlegame127 and id is 1 raw text is: Int J Legal Med (2013) 127:1-6
DOI 10.1007/s00414-011-0646-6
ORJGINAL4 ARTICLE
Differential pattern of genetic variability at the DXYS156
locus on homologous regions of X and Y chromosomes
in Indian population and its forensic implications
Sanjukta Mukerjee - Meeta Mukherjee - Tania Ghosh-
D. Kalpana - Anil Kumar Sharma
Received: 13 February 2011 /Accepted: 31 October 2011 /Published online: 25 November 2011
C Springer-Verlag 2011

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 misidenti-
fication. 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)~ 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 valida-
tion studies. Two population samples and few validation
samples which showed erroneous results for the ameloge-
nin 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.
Electronic supplementary material The online version of this article
(doi:10.1007/s00414-011-0646-6) contains supplementary material,
which is available to authorized users.
S. Mukerjee - M. Mukherjee - T. Ghosh - D. Kalpana
A. K. Sharma (E)
Ministry of Home Affairs, Government of India, Central Forensic
Science Laboratory, Directorate of Forensic Science Services,
30 Gorachand Road, Park Circus,
Kolkata, West Bengal 700014, India
e-mail: aks4n6@gmail.com

Statistical parameters of forensic interest indicate that the
DXYS156 locus is polymorphic and discriminating for the
Indian population.
Keywords Sex determination - Amelogenin - DXYS156-
Pentanucleotide repeat - Indian population
Introduction
Determining the gender of human DNA samples is of prime
importance in forensics. The amelogenin locus is routinely
used for sex determination of a sample because it resides on
homologous regions of the sex chromosomes [1]. PCR
primers are designed spanning the 6-bp deletion on X
chromosome to produce differentially sized amplicons (106
and 112 bp) for the X and Y chromosomes, respectively
[2]. However, this method can sometimes misidentify a
male as a female due to a deletion in the AmelY region. This
deletion has been reported to occur at a frequency of 0.08%
in Caucasian males, 1.8% in Indians, and as high as 8% in
Sri Lankans [3-6]. Varying lengths of interstitial deletions
ranging from 1.0 Mb to around 3.8 Mb have been observed
on the pericentromeric region of the short arm of Y
chromosome, which may include the amelogenin locus [7,
8]. The deletion in AmelY region does not have consider-
able consequence on enamel formation because of the
presence of the X homologue but has important implica-
tions for forensic casework [9].
Several authors have suggested the inclusion of addi-
tional Y locus for conclusive sex test and to prevent gender
mistyping. Chen et al. [10] first described and characterized
the presence of a pentanucleotide repeat [(TAAAA)~]
DXYS156, which maps to both the sex chromosomes and
can be used for genetic identity testing. The microsatellite

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