An X-chromosome pentaplex in two linkage groups: Haplotype data in Alagoas and Rio de Janeiro populations from Brazil

Abstract 

Genotype data were obtained for five X-Chr STRs (DXS10079, DXS10074, DXS10075, DXS7424 and DXS101) in two different populations from Brazil, namely Alagoas and Rio de Janeiro. Observed genotype distributions in female samples for each locus do not show deviations from Hardy–Weinberg equilibrium expectations. Gametic association was tested for all pairs of loci in male samples. Significant association values were found between all pairs including DXS10079, DXS10074 and DXS10075, as well as between DXS7424 and DXS101, proving that these two groups of markers must be treated as haplotypes. No significant association could be found between markers from the two groups (DXS10079, DXS10074 or DXS10075 vs. DXS7424 or DXS101), although distances between them varied from 24 to 25cM. When comparing haplotype frequencies in Alagoas, Rio de Janeiro, Germany and Ghana, significant differences were found between the Brazilian and the Germany sample and that from Ghana. Nevertheless, no significant differences were found between Alagoas and Rio de Janeiro, as well as between these two populations and Germany. The combined power of discrimination in males and females were high in both Brazilian populations (≥0.9996 and ≥0.9999998, respectively), showing the utility of these markers for human identification and paternity testing.

Keywords: STRs, X-chromosome, Brazil, Forensic, Population genetics