Estudo da frequência haplotípica dos marcadores microssatélites ligados ao cromossomo X, DXS7424, DXS101, DXS10079, DXS10075 e DXS10074 na população de Alagoas

Abstract

The STR markers linked to the X chromosome can be used for complement the analysis of autosomal markers, especially in complex cases of kinship testing, in cases of post-morten identification and in paternity testing, when the disputed child is a girl. The aim of this work was investigate five STR X-chromosome markers (DXS10079, DXS10074, DXS10075, DXS7424 and DXS101) in the population of Alagoas, Brazil and analyze their frequencies for forensic purposes. The sample was composed of 404 unrelated individuals, 203 males and 201 females. The DNA was extracted using Chelex procedure and amplification was performed by PCR in a pentaplex system and the fragments were separated by capillary electrophoresis. For the studied STR markers, it was calculated the allele and haplotype frequencies, the observed and expected Heterozygosity values, the Hardy–Weinberg equilibrium (HWE), the genetic diversity, the Mean Exclusion Chance of trios involving daughters (MECT) as well as in father/daughter duos (MECD). Also, it was calculated Power of Discrimination in males (PDM) and in females (PDF) and the Polymorphism Information Content (PIC). The forensic efficiency values demonstrate that DXS101 is a highly informative marker, followed by DXS10074, DXS10079, DXS7424 and DXS10075. The polymorphism information content ranged from 0.7470 to 0.8858. For the pentaplex evaluated, the combined values of PDM and PDF were 0, 9998947 and 0, 9999998, respectively and the combined MEC in trios involving daughters and in father/daughter duos were 0,999817 and 0,998042, respectively. No deviations from the Hardy–Weinberg equilibrium were observed. We concluded that the five ChrX STRs analyzed are highly informative markers for kinship testing and constitute a powerful tool for forensic practice in our population.