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THE CORRELATION BETWEEN ANCESTRY AND COLOR IN TWO CITIES OF NORTHEAST BRAZIL WITH CONTRASTING ETHNIC COMPOSITIONS
Censos
Desequilíbrio de ligação
Cidades
Negros
Brasil
Humanos
Author
Affilliation
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Case Western Reserve University. Center for Global Health. Cleveland, OH, USA.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
State University Santa Cruz. Ilhéus, BA, Brasil.
State University Santa Cruz. Ilhéus, BA, Brasil.
Case Western Reserve University. Department of Genetics. Cleveland, OH, USA.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Case Western Reserve University. Department of Genetics. Cleveland, OH, USA / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Case Western Reserve University. Center for Global Health. Cleveland, OH, USA.
Case Western Reserve University. Center for Global Health. Cleveland, OH, USA.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
State University Santa Cruz. Ilhéus, BA, Brasil.
State University Santa Cruz. Ilhéus, BA, Brasil.
Case Western Reserve University. Department of Genetics. Cleveland, OH, USA.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Case Western Reserve University. Department of Genetics. Cleveland, OH, USA / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil.
Federal University of Bahia. Institute for Collective Health. Salvador, BA, Brasil.
Case Western Reserve University. Center for Global Health. Cleveland, OH, USA.
Abstract
The degree of admixture in Brazil between historically isolated populations is complex and geographically variable. Studies differ
as to what the genetic and phenotypic consequences of this mixing have been. In Northeastern Brazil, we enrolled 522 residents
of Salvador and 620 of Fortaleza whose distributions of self-declared color were comparable to those in the national census.
Using the program Structure and principal components analysis there was a clear correlation between biogeographic ancestry
and categories of skin color. This correlation with African ancestry was stronger in Salvador (r=0.585; Po0.001) than in
Fortaleza (r=0.236; Po0.001). In Fortaleza, although self-declared blacks had a greater proportion of European ancestry,
they had more African ancestry than the other categories. When the populations were analyzed without pseudoancestors, as in
some studies, the relationship of ‘race’ to genetic ancestry tended to diffuse or disappear. The inclusion of different African
populations also influenced ancestry estimates. The percentage of unlinked ancestry informative markers in linkage
disequilibrium, a measure of population structure, was 3–5 times higher in both Brazilian populations than expected by chance.
We propose that certain methods, ascertainment bias and population history of the specific populations surveyed can result in
failure to demonstrate a correlation between skin color and genetic ancestry. Population structure in Brazil has important
implications for genetic studies, but genetic ancestry is irrelevant for how individuals are treated in society, their health, their
income or their inclusion. These track more closely with perceived skin color than genetic ancestry.
Keywords in Portuguese
Pigmentação da peleCensos
Desequilíbrio de ligação
Cidades
Negros
Brasil
Humanos
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