Estudo diz que cerca de 70% da herança genética nacional vem da Europa
Variação de região para região do país é baixa; cor da pele tem elo com poucos genes e, por isso, é parâmetro enganoso
REINALDO JOSÉ LOPES
EDITOR DE CIÊNCIA
No Brasil, faz cada vez menos sentido considerar que brancos têm origem europeia e negros são "africanos". Segundo um novo estudo, mesmo quem se diz "preto" ou "pardo" nos censos nacionais traz forte contribuição da Europa em seu DNA.
O trabalho, coordenado por Sérgio Danilo Pena, da UFMG (Universidade Federal de Minas Gerais), indica ainda que, apesar das diferenças regionais, a ancestralidade dos brasileiros acaba sendo relativamente uniforme.
"A grande mensagem do trabalho é que [geneticamente] o Brasil é bem mais homogêneo do que se esperava", disse Pena à Folha.
De Belém (PA) a Porto Alegre, a ascendência europeia nunca é inferior, em média, a 60%, nem ultrapassa os 80%. Há doses mais ou menos generosas de sangue africano, enquanto a menor contribuição é a indígena, só ultrapassando os 10% na região Norte do Brasil.
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The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected
Sérgio D. J. Pena 1 et al
1 Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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.
Citation: Pena SDJ, Di Pietro G, Fuchshuber-Moraes M, Genro JP, Hutz MH, et al. (2011) The Genomic Ancestry of Individuals from Different Geographical Regions of Brazil Is More Uniform Than Expected. PLoS ONE 6(2): e17063. doi:10.1371/journal.pone.0017063
Editor: Henry Harpending, University of Utah, United States of America
Received: October 30, 2010; Accepted: January 18, 2011; Published: February 16, 2011
Copyright: © 2011 Pena et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was supported by the Financiadora de Estudos e Projetos (FINEP) of Brazil, by contract 01.08.0123.00 to the Rede Nacional de Farmacogenética/-genômica - REFARGEN. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: spena@dcc.ufmg.br
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