Diversidade genética e desempenho forense da análise de haplótipos de locos microssatélites no cromossomo Y em populações brasileiras.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

DNA polymorphisms on the human Y chromosome have increasingly been used for evolutionary studies and individual identification. Y chromosome STRs show moderate levels of polymorphism and typically spiky allele frequency distributions when compared to autossomal STRs. The patrilineal inheritance of the non recombining portion of the Y chromosome results in the complete conservation of linked polymorphisms. When taken together, these polymorphisms yield highly discriminating haplotypes for forensic investigation of rape cases when mixtures of male and female fluids need to be analyzed, and a powerful complementary tool in paternity testing of a deceased alleged father when a male offspring is in question. We have employed a single gel lane assay of an extremely informative Y-STR core set or minimal haplotype amplified in two multiplex reactions internationally recommended for court use involving the following locos: DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385I/II. A database was constructed by typing a sample of approximately 250 unrelated Brazilian males, 50 from each of the five Brazilian geopolitical regions. Alleles were declared based on internal size standards and reference samples of known haplotypes from the ISFG typing exercises. Allele and haplotype frequencies as well as gene diversity values were estimated for each region and loco. The average gene diversity that corresponds to the power of paternity exclusion (PE) was 63.7%. Locos DYS385I, DYS385II and DYS389II were the most informative with PE above the 70% range, and locos DYS391 and DYS393 the least informative, below the 55% range. A remarkable haplotype diversity of 99.8% was found when all five regions together were analyzed, resulting in an estimate of combined power of individual discrimination of 87 %.The most frequent Y-STR haplotypes observed in Brazil indicate a predominant contribution of European males in the formation of the current Brazilian population corroborating previous reports based on slower evolving bialelic Y polymorphisms. No significant differentiation for the Y-STR haplotype was seen among urban populations in the five regions based on an exact test and bootstrap resampling (Fst = 0.00031; p value = 0.43326). The AMOVA indicated that 99.97% of the haplotypic variation is found within regions and only 0.03% between regions. This result indicates that a single national database of Y-STR haplotype frequencies can be confidently used in the quantitative assessment of matches in forensic casework in Brazilian populations.

ASSUNTO(S)

cromossomo y genética forense microssatélites polymorphisms genética - análise chromosome ciências biológicas

ACESSO AO ARTIGO

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