Polymorphic Alu insertions in six Brazilian African‐derived populations

Abstract

At least 25 African-derived populations (quilombo remnants) are believed to exist in the Ribeira River Valley, located in the southern part of São Paulo State, Brazil. We studied four Alu polymorphic loci (APO, ACE, TPA25, and FXIIIB) in individuals belonging to six quilombo remnants in addition to individuals sampled from the city of São Paulo. The allelic frequencies observed in the quilombo remnants were similar to those previously observed in African-derived populations from Central and North America. Genetic variability indexes (Fst and Gst values) in our quilombos were higher than the reported values for the majority of other populations analyzed for the same kind of markers, but lower than the variability usually observed in Amerindian groups. The observed high degree of genetic differentiation may be due to genetic drift, especially the founder effect. Our results suggest that these populations behave genetically as semi-isolates. The degree of genetic variability within populations was larger than among them, a finding described in other studies. In the neighbor-joining tree, some of the Brazilian quilombos clustered with the African and African-derived populations (São Pedro and Galvão), others with the Europeans (Pilões, Maria Rosa, and Abobral). Pedro Cubas was placed in an isolated branch. Principal component analysis was also performed and confirmed the trends observed in the neighbor-joining tree. Overall, the quilombos showed a higher degree of gene flow than average when compared to other worldwide populations, but similar to other African-derived populations.

Multilocus Family-Based Association Analysis of Seven Candidate Polymorphisms with Essential Hypertension in an African-Derived Semi-Isolated Brazilian Population

“…As described previously, quilombos may be an important target population for genetic studies of complex diseases, since this population displays peculiar genetic and environmental characteristics [8]. Specifically, quilombos are known not only to have a large contribution of African genes, but also strong founder effects, a substantial degree of inbreeding, and high prevalence of essential hypertension as well as overweight [7–10, 24]. …”

Interethnic admixture and the evolution of Latin American populations

“…Scliar et al (2009); 9. Kimura et al (2013); a subset of these communities was also studied for two Alu insertions, and the values used to estimate parental contributions (Cotrim et al , 2004), but the results obtained showed inconsistencies among the populations and were not considered; 10. Francez et al (2011a); 11.…”

Association of polymorphisms at the ADIPOR1 regulatory region with type 2 diabetes and body mass index in a Brazilian population with European or African ancestry

“…Although quilombo remnants form a semi-isolated population (15), no significant difference in SNP c.10225C>G minor allele frequency was found compared to the Brazilian AfA groups. Minor allele frequency in our AfA sample (-8503A = 0.16 and 10225G = 0.52) was different from that in African-Americans (-8503A = 0.36 and 10225G = 0.42).…”

“…Previous to the abolition of slavery in Brazil, many fugitive African slaves founded communities called "Quilombos". Currently, population groups living in Quilombos are referred as quilombo remnants, who are partially genetically isolated (15). Data on systolic blood pressure, diastolic blood pressure, height, weight, BMI, waist circumference, and plasma glucose level were available for the quilombo remnant individuals (15).…”