Padrões de herança paterna em populações da América do Sul

Abstract

The paternal admixture patterns currently observed in South American populations result from the encounter of native groups with Europeans and African populations. In addition, recent migrations from Europe and other countries in South America have also contributed to their genetic structure. Therefore, it is important to build genetic databases that capture the high genetic diversity and heterogeneity in different South American population groups. Due to their non-recombining nature and uniparental transmission, Y chromosome markers are widely used in population genetics to infer genealogical history and migrations of human populations. This study aimed to contribute to the study of the paternal lineages of South American populations, characterizing Y chromosome markers. Therefore, 2,202 samples from unrelated men, residing in Argentina, Brazil, Colombia, Ecuador and Paraguay, were genotyped for PowerPlex Y23. Furthermore, part of these samples was analyzed for 67 Y-SNPs. In addition to the main objective, marker-specific mutation rates were estimated in parent-child pairs, as part of a collaborative study, to increase the precision of mutation rate estimates in Y-STRs. A high haplotypic diversity was found in the studied populations (>0.9997), similar to what was observed for 14 other Latin American populations, for the 23 Y-STR markers. The analysis of genetic distances (FST) between the populations studied in this work and other populations in South America, as well as with European, African and Native American populations, revealed a greater proximity between the South American and the Iberian populations, except Bolivia and Peru, most probably due to the greater native component of these populations. In the analysis of haplogroups defined by Y-SNPs, a predominance of European paternal lineages was observed in the populations studied (>73.5%), with haplogroup R1b-S116, originating from the Iberian Peninsula, being the most frequent. The relative proportion of lineages of Native American and African origin varied between countries, with the highest proportion of native lineages being observed in Ecuador, and Brazilian populations and Colombia showing a predominance of African lineages over native ones, confirming what was expected from historical data. Finally, mutation rates calculated for 201 parent-child duos, together with those generated by other groups, totaling 84,715 allelic transfers, showed that: (i) single-step mutations showed to be more common than multi-step ones; (ii) longer alleles showed to be nearly twice more mutable than the shorter ones and the loss of repeats showed to be nearly twice more likely than the gain while short ones gain them; and (iii) the mutation rate and the father's age are positively correlated. The results obtained contributed to knowledge about the evolutionary and migratory processes that gave rise to contemporary South American populations.