Caracterização da população do Estado de Mato Grosso, Brasil para marcadores STR do cromossomo Y

Abstract

Genotyping of Y chromosome short tandem repeats markers (Y-STRs) is a powerful tool in forensic practice, complementing the analysis of traditional autosomal STR markers (AS-STR). Taking into accoung that the Y-STRs constitute a single haplotype whose loci are in strong linkage disequilibrium, it is necessary to obtain the frequency of the Y-STR haplotype directly in the reference population of the sample in question. Thus, it is interesting to combine Brazilian samples from different populations to obtain a diverse and representative Brazilian database of Y-STR haplotypes. Objectives - To characterize the population of the State of Mato Grosso (MT), Brazil, for 23 Y-STR markers; to make such data available in Y chromosome forensic banks; to evaluate the forensic efficiency of this system and the existence of genetic substructure of this population, compared to the others in the Brazil. Casuistic and Methods - Blood samples from 200 males residing in the state of MT were collected, followed by DNA extraction. The amplification of the 23 Y-STRs (DYS576, DYS389I, DYS448, DYS389II, DYS191, DYS391, DYS481, DYS537, DYS538, DYS438, DYS437, DYS635, DYS390, DYS439, DYS392 DYS456 and Y-GATA-H4) were performed using the PowerPlex® Y23 (PPY23) system and submitted to capillary electrophoresis and genotyping to obtain haplotypic profiles. Allelic and haplotypic frequencies, pairwise genetic distance calculation (FST and RST), analysis of molecular variance (AMOVA), and forensic efficiency test of the system used (discrimination capacity and haplotypic diversity) were accessed. Results – A total of 197 different haplotypes were obtained; 194 unique and three observed twice in the population. Markers DYS458 and DYS385 showed intermediate alleles and the mean genetic diversity of all loci was 0.675. Peer-to-peer genetic distance analysis performed with 22 Brazilian populations of mixed origin showed that only 20 (FST) and 22 (RST) pairs had significant P values, highlighting populations from the Northern region of Brazil, but with genetic distance values considered to be low differentiation, confirmed in the nonmetric multidimensional scale (MDS) graphs, as well as the proximity of the miscegenated metapopulation with the European one. Analysis of molecular variance indicated 99.55% of genetic variation within populations from different geographic regions of Brazil. Conclusion - It is emphasized the genetic homogeneity in the population of Mato Grosso, in relation to the populations of mixed origin distributed in the five geopolitical regions of Brazil, moreover, the PPY23 system is efficient with discrimination capacity and high haplotypic diversity.