Determinação da ancestralidade em populações da América do Sul

Abstract

Latin America has an admixed population made up of three ancestral groups: Amerindians, Europeans and Africans. The Native Americans were the first to occupy the American continent followed by the Europeans (in South America initially arrived the Spaniards and the Portuguese) and finally by the Africans who were brought to America as slave labor. This region has unique geographical, archaeological and historical records that are distinct from other regions of the Americas, which makes the populations of this subcontinent present interesting characteristics for the understanding of migration processes and admixture. The relative proportions of the ancestral populations that contribute to the formation of an admixed population can be estimated through ancestry informative markers (AIMs) characterized by a high diversity among groups of different continents. However, the results obtained based on the study of this type of markers present a degree of uncertainty that will depend on their allelic frequency differences, presented by these in the ancestral populations, as well as on the number of markers used. Thus, the greater the allelic differences between reference populations and the number of markers used, the lower the confidence intervals associated with the ancestry estimates obtained. In the present study, we evaluate the proportions of ancestry in different Latin American populations (Brazil - RJ, Colombia and Paraguay) and possible levels of population sub-structure. In addition, we test different ancestry inference strategies: (i) using 46 AIM-Indels (Pereira et al., 2012) and (ii) using 165 AIM-SNPs (HID-Ion AmpliSeq-Ion Torrent). The results obtained allowed the enlargement of the database for the populations of State of Rio de Janeiro and five regions of Colombia. For the first time, the ancestry genetic profile of the admixed population of Paraguay was evaluated. The HID-Ion AmpliSeq-Ion Torrent Ancestry Panel proved to be efficient in detecting sample variability and reducing the differences between sibling pairs. And finally, was observed the heterogeneity already expected among these population groups, which reflect the complex process of admixture that originated the present populations of Latin America.