Abstract
The genetic background of the Brazilian population is mainly characterized by three parental populations: European, African, and Native American. The aim of this study was to overview the genetic ancestry estimates for different Brazilian geographic regions and analyze factors involved in these estimates. In this systematic scoping review were included 51 studies, comprehending 81 populations of 19 states from five regions of Brazil. To reduce the potential of bias from studies with different sampling methods, we calculated the mean genetic ancestry weighted by the number of individuals. The weighted mean proportions of European, African, and Native American ancestries were 68.1%, 19.6%, and 11.6%, respectively. At the regional level, the highest European contribution occurred in the South, while the highest African and Native American contributions occurred in the Northeastern and Northern regions, respectively. Among states in the Northeast region, Bahia and Ceará showed significant differences, suggesting distinct demographic histories. This review contributes for a broader understanding of the Brazilian ancestry and indicates that the ancestry estimates are influenced by the type of molecular marker and the sampling method.
Highlights
The Brazilian population has one of the most heterogeneous genetic constitutions in the world with a predominant tri-hybrid composition and an extensive admixture (Sans, 2000)
70 studies were excluded
We performed an extensive review of the literature for a better understanding of the heterogeneity of the Brazilian population from different geographic regions and analyzed the influence of some factors, such as the molecular marker type and number of samples, in ancestry estimates
Summary
The Brazilian population has one of the most heterogeneous genetic constitutions in the world with a predominant tri-hybrid composition and an extensive admixture (Sans, 2000). This admixture is the result of more than 500 years of interethnic crosses between Native Americans, European colonizers, and African slaves. Recent surveys of genetic diversity in Native Americans replaced the hypothesis of a single stream of migration to a complex scenario involving multiple sources (Reich et al, 2012). Other ancestral population streams were detected with extensive gene flow among them (Lell et al, 2002; de Azevedo et al, 2011; Reich et al, 2012)
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