The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected

Abstract

Based on pre-DNA racial/color methodology, clinical and pharmacological trials have traditionally considered the different geographical regions of Brazil as being very heterogeneous. We wished to ascertain how such diversity of regional color categories correlated with ancestry. Using a panel of 40 validated ancestry-informative insertion-deletion DNA polymorphisms we estimated individually the European, African and Amerindian ancestry components of 934 self-categorized White, Brown or Black Brazilians from the four most populous regions of the Country. We unraveled great ancestral diversity between and within the different regions. Especially, color categories in the northern part of Brazil diverged significantly in their ancestry proportions from their counterparts in the southern part of the Country, indicating that diverse regional semantics were being used in the self-classification as White, Brown or Black. To circumvent these regional subjective differences in color perception, we estimated the general ancestry proportions of each of the four regions in a form independent of color considerations. For that, we multiplied the proportions of a given ancestry in a given color category by the official census information about the proportion of that color category in the specific region, to arrive at a “total ancestry” estimate. Once such a calculation was performed, there emerged a much higher level of uniformity than previously expected. In all regions studied, the European ancestry was predominant, with proportions ranging from 60.6% in the Northeast to 77.7% in the South. We propose that the immigration of six million Europeans to Brazil in the 19th and 20th centuries - a phenomenon described and intended as the “whitening of Brazil” - is in large part responsible for dissipating previous ancestry dissimilarities that reflected region-specific population histories. These findings, of both clinical and sociological importance for Brazil, should also be relevant to other countries with ancestrally admixed populations.

Mucolipidosis types II and III and non-syndromic stuttering are associated with different variants in the same genes

“…The excess of rare variants in cases compared with controls existed within all subpopulations in our sample, including those of European origin (75/578 cases vs 10/276 controls, χ 2 = 18.23, P = 1.9 × 10 − 5 ) and those of African ancestry including Brazilians, who have a large component of African ancestry, 14 (79/311 cases vs 31/305 controls, χ 2 = 24.4, P = 7.93 × 10 − 7 ).…”

The Genetic Diversity of the Americas

“…A common aim of these studies has been to relate current genetic patterns to aspects of the recent demographic history of the countries examined. In Brazil, for instance, the highest levels of European ancestry have been documented in the south of the country (the area of strongest European immigration during the "whitening" of Brazil), whereas the highest levels of African ancestry are in the northeast (historically the main area of African slave concentration) (72,82). Similarly, in US African Americans, African ancestry is highest in southern states, the area historically most strongly associated with slavery (9,19), and a south-to-north gradient of increasing European admixture has been interpreted as related to the northern migration of African Americans after the abolition of slavery (9,19,68,69).…”

“…By default, genetic studies of US population samples categorize individuals as European American, African American, Hispanic, or Asian (42,51,74,94,105). In Ibero-America, such categorization of research subjects is not standard, but studies of this type have been performed for some urban population samples (particularly in Brazil) (70,72,93,101) and for certain historic isolates (e.g., African-derived Brazilian Quilombos) (79). Studies in Ibero-America use the terms "white" and "black" as ancestry equivalents to the European American and African American categories used in the United States, we therefore focused on a comparison of these two categories across the continent.…”

Accuracy of mandibular measurements of sexual dimorphism using stabilizer equipment

“…In addition, when the genomic ancestry of Brazilian individuals was evaluated, low differences were observed among the regions of the country. 21 …”