RESUMO
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.
Assuntos
Cromossomos Humanos X , Cromossomos Humanos Y , Loci Gênicos , Variação Genética , Análise para Determinação do Sexo/métodos , Amelogenina/genética , Frequência do Gene , Genética Populacional , Humanos , Índia , Masculino , Repetições de Microssatélites , Reação em Cadeia da PolimeraseRESUMO
X chromosomal short tandem repeats have the potential to complement the analyses of the autosomal, Y chromosomal, and mitochondrial DNA markers in forensics and population genetics, and extensive research on X chromosomal markers is being carried out. In the present study, a decaplex for the co-amplification of ten X chromosomal microsatellite loci (DXS6807, DXS8378, DXS7132, DXS6809, DXS6789, DXS101, DXS7133, GATA172D05, HPRTB, and GATA31E08) was optimized and 749 blood samples of unrelated male individuals from the four major linguistic families of India were analyzed. The number of alleles for the studied loci ranged from 7-16 while the gene diversity values varied from 0.408 to 0.855. Two new alleles were observed for the loci DXS101 and HPRTB. Statistical parameters of forensic interest were calculated and all loci were found to be polymorphic. High power of discrimination was observed for the loci DXS101, DXS6809, and DXS6789. The present study demonstrates the efficacy of these X-linked markers for human identification and kinship analysis.
Assuntos
Cromossomos Humanos X , Variação Genética , Genética Populacional , Sequências de Repetição em Tandem , Impressões Digitais de DNA , Etnicidade/genética , Frequência do Gene , Genótipo , Humanos , Índia , Masculino , Reação em Cadeia da PolimeraseRESUMO
Allele frequencies and forensic parameters were estimated for 11 X chromosome STRs (DXS9898, DXS7424, DXS981, DXS8377, DXS9895, DXS10161, DXS10164, DXS6800, DXS6801, DXS9902 and DXS7423) from 749 samples of unrelated male individuals belonging to eleven populations of India.
Assuntos
Cromossomos Humanos X/genética , Frequência do Gene/genética , Loci Gênicos/genética , Genética Populacional , Humanos , Índia , Masculino , Sequências de Repetição em TandemRESUMO
Seventeen short tandem repeats (DYS389I, DYS390, DYS389II, DYS19, DYS385a/b, DYS393, DYS391, DYS392, DYS439, DYS438, DYS456, DYS458, DYS635, Y(GATA)H4, DYS437, and DYS448) from the non-recombining region of the human Y-chromosome were analyzed in 750 unrelated males representing four major linguistic families of India using AmpFlSTR(®) Yfiler(®) PCR Amplification kit. A total of 612 distinct haplotypes were observed, of which 545 were unique. Rare alleles for the loci DYS456, DYS458, DYS635, Y(GATA)H4, and duplication at the loci DYS389I and DYS389II were also observed. To understand the genetic diversity of the Indian population, and utility of Y-STRs in forensics, the locus diversity, haplotype diversity, and discrimination capacity in all populations was determined. MDS plot based on pairwise Φ(st) and AMOVA revealed the high genetic heterogeneity among the Indian populations due to linguistic diversity and social stratification.