Genomic ancestry in urban Afro-Brazilians

Muniz, Yara Costa Netto; Ferreira, Luzitano Brandão; Mendes-Junior, Celso Teixeira; Wiezel, Cláudia Emília Vieira; Simões, Aguinaldo Luíz

doi:10.1080/03014460701782256

Cited by 28 publications

(27 citation statements)

References 13 publications

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“…Additionally, the predominant European male contribution has been also described in earlier analyses using Y chromosome markers (Builes et al 2007). The European ancestry proportion estimated in this group is lower than those described in studies of Latin American populations as Mexicans, Afro-Brazilians, Venezuelan, Costa Rican, and Colombians (Bedoya et al 2006;Bonilla et al 2004a, b;Carvajal-Carmona et al 2000;Martinez-Marignac et al 2007;Martinez et al 2007b;Morera et al 2003;Muniz et al 2008;Salari et al 2005;Shriver et al 2003), but higher than those in Mexican mestizos from Mexico city and African Americans (Juarez-Cedillo et al 2008;Parra et al 1998;Shriver et al 2003). On the contrary, the African ancestry in this population located in the Caribbean Coast of Colombia is lower than those described in other African Caribbean (Benn-Torres et al 2008;Miljkovic-Gacic et al 2005), and African American populations ) but higher than those described in urban Afro-Brazilian, Venezuelan and Costa Rican populations (Martinez et al 2007b;Morera et al 2003;Muniz et al 2008).…”

Section: Discussionmentioning

confidence: 75%

African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia

et al. 2009

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African descended populations exhibit an increased prevalence of asthma and allergies compared to Europeans. One approach to distinguish between environmental and genetic explanations for this difference is to study relationships of asthma risk to individual admixture. We aimed to determine the admixture proportions of a case-control sample from the Caribbean Coast of Colombia currently participating in genetic studies for asthma, and to test for population stratification and association between African ancestry and asthma and total serum IgE levels (tIgE). We genotyped 368 asthmatics and 365 non-asthmatics for 52 autosomal ancestry informative markers, six mtDNA haplogroups and nine haplogroups and five microsatellites in Y chromosome. Autosomal admixture proportions, population stratification, and associations between ancestry and the phenotypes were estimated by ADMIXMAP. The average admixture proportions among asthmatics were 42.8% European, 39.9% African and 17.2% Native American and among non-asthmatics they were 44.2% (P = 0.068), 37.6% (P = 0.007) and 18.1% (P = 0.050), respectively. In the total sample, the paternal contributions were 71% European, 25% African and 4.0% Native American and the maternal lineages were 56.8% Native American, and 20.2% African; 22.9% of the individuals carried other non-Native American mtDNA haplogroups. African ancestry was significantly associated with asthma (OR: 2.97; 95% CI: 1.08-8.08), high tIgE (OR: 1.9; 95% CI: 1.17-3.12) and socioeconomic status (OR = 0.64; 95% CI: 0.47-0.87). Significant population stratification was observed in this sample. Our findings indicate that genetic factors can explain the association between asthma and African ancestry and suggest that this sample is a useful resource for performing admixture mapping for asthma.

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Section: Discussionmentioning

confidence: 75%

African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia

et al. 2009

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“…4,5,7,[22][23][24] In contrast, this paper is only one of many showing that Brazil can exhibit marked population structure, and self-identified skin color is generally consistent with the dominant or relative ancestral contribution. 6,8,[25][26][27][28][29] In this study, for both cities, blacks were twice as African as others in the surrounding population and whites more European, whereas the browns were intermediate. However, within localities, the designation of skin color may be relative to the ancestral mixture of one's neighbors.…”

Section: Discussionmentioning

confidence: 84%

The correlation between ancestry and color in two cities of Northeast Brazil with contrasting ethnic compositions

et al. 2014

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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; P<0.001) than in Fortaleza (r=0.236; P<0.001). 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.

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“…These proportions are in agreement with expectations for the urban population of the State of São Paulo, given its ethnic composition. 41 It should be emphasized that in this classification scheme, ancestry or phenotypic characters other than the skin color have a secondary role. The PCR products were directly sequenced in an ABI310 Genetic Analyzer (Applied Biosystems, Foster City, CA, USA) using the reverse primer HLAG8R to prevent sequence overlaps in heterozygous 14-bp samples.…”

Section: Subjectsmentioning

confidence: 99%

The genetic structure of 3′untranslated region of the HLA-G gene: polymorphisms and haplotypes

et al. 2009

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The HLA-G gene is predominantly expressed at the maternal-fetal interface. It has been associated with maternal-fetal tolerance and in the inhibition of cytotoxic T lymphocyte and natural killer cytolytic functions. At least two variations in the 3'untranslated region (UTR) of HLA-G locus are associated with HLA-G expression levels, the 14-bp deletion/insertion polymorphism and the +3142 single-nucleotide polymorphism (SNP). However, this region has not been completely characterized yet. The variability of the 3'UTR of HLA-G gene and its haplotype structure were characterized in 155 individuals from Brazil, as well as HLA-G alleles associated with each of the 3'UTR haplotype. The following eight variation sites were detected: the 14-bp polymorphism and SNPs at the positions +3003T/C, +3010C/G, +3027A/C, +3035C/T, +3142G/C, +3187A/G and +3196C/G. Similarly, 11 different 3'UTR haplotypes were identified and several HLA-G alleles presented only one 3'UTR haplotype. In addition, a high linkage disequilibrium among the variation sites was detected, especially among the 14-bp insertion and the alleles +3142G and +3187A, all previously associated with low mRNA availability, demonstrating that their effects are not independent. The detailed analyses of 3'UTR of the HLA-G locus may shed some light into mechanisms underlying the regulation of HLA-G expression.

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Genomic ancestry in urban Afro-Brazilians

Cited by 28 publications

References 13 publications

African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia

African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia

The correlation between ancestry and color in two cities of Northeast Brazil with contrasting ethnic compositions

The genetic structure of 3′untranslated region of the HLA-G gene: polymorphisms and haplotypes

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