Genetic Attributes of the YHRD Minimal Haplotype in 10 Provinces of Argentina.

MIGUEL MARINO, ANDREA SALA AND DANIEL CORACH

Insbruck-Austria

Congreso; 5th International Y-User Workshop "The Y chromosome in forensic, clinical and evolutionary genetics"; 2006

In the last few years, the Y-STRs became a powerful complement for the DNA-based forensic identification procedures. Due to the inherent attributes of the Y chromosome: lack of recombination ability and, hence, patrilineage inheritance, the Y-STRs allows to identify a male lineage but not individuals. The source of variation is provided by mutation and its rate is similar to that exhibited by the autosomal STRs. This may provide a sensitive tool for addressing recent historical events. Nowadays population of Argentina is the result of the genetic contribution of diverse ethnic groups, mainly aboriginal and european. The begging of the admixture process can be precisely dated in 1536, when the first Spanish conquerors invaded the territory that is, at present, occupied by Argentina. In less than 20 generations a remarkable change occurred in the demography of the region. Since these markers are been used routinely in forensic casework since 1996 in our lab, the quantity of available haplotypes allowed to analyze the genetic attributes in a countrywide extent. Nine Y-STRs, representing the minimal YHRD haplotype (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393 and DYS385a/b) were investigated in 959 unrelated males from 10 provinces of Argentina (Buenos Aires, Santa Fé, Mendoza, Río Negro, Chubut, Corrientes, Chaco, Formosa, Misiones and Salta). As outgroups 145 individuals belonging to three different Amerindian tribes were included in this study. Members of the Guaraní tribe, from the Misiones province, and Tobas and Pilagas tribes, from the Formosa province, were selected. Haplotype frequency distribution was determined either for Argentina as a whole or for each province, as well as for the Amerindian populations in order to establish if geographical differences were detectable. It was demonstrated that 609 out of 959 individuals, depicted different haplotypes (63.5%). Two of them denoted relatively high frequency (~3%). The overall Argentinean population exhibited a considerable Gene Diversity (GD= 0.996), similar to the European populations. However, when the GD values of 13 analyzed populations were evaluated, the Northern and the aboriginal groups denoted remarkably lower GD values. By AMOVA it was determined the extent of population stratification. A remarkable degree of homogeneity and no significant differences between the investigated provinces was detected. When the Amerindian populations are also compared, the differences became highly significant.  Genetic distance determined by Rst, showed three clusters, one of them, included Southern region (Chubut and Río Negro provincies) together with Santa Fe province (Center), the second one includs Central and Northern region provinces (except Santa Fe) and the last one includs the aboriginal groups. The only North Western province of Argentina included in this study is Salta, shows significant difference when compared with the other provinces, the same happens with the three Amerindian tribes, constituting a separated cluster, with no significant differences between them. The results presented herein show the possible impact of the European immigrants on the native aboriginal populations in terms of the male contribution. It has been shown that only about 17% of the male lineages are of Amerindian ancestry. Accordingly, it becomes apparent that a more informative platform might be required for forensic purposes as that offerd by the combined use of Y-STRs and Y-SNPs.