DRD2 TaqI haplotypes in three urban Brazilian populations

Abstract

Brazil is a continental-sized country divided into five geographic regions, each one with different history of colonization and human settlement. Manaus, located at the North region, is the capital of Amazonas. It suffered large populational influx mainly during the Rubber Age (1870–1920), and due to the Zona Franca de Manaus (established in 1967). Goiás is a Middle-Western state and its population increased with the discovery of gold, on the 17th century. The Federal District was relocated from Rio de Janeiro to the Middle-West in 1960, and since then has received people from all other regions of Brazil. Therefore, this population has been being considered as a reflex of Brazil's population. Here we describe the distribution of the DRD2 TaqI A, B and D haplotypes in Federal District, Manaus and Goiás. For this purpose, a total of 353 samples from Manaus (42), Federal District (134) and Goiás (177) were analyzed by using PCR and RFLP techniques. Data were analyzed employing Arlequin 3.11 and GENEPOP 3.4. Manaus was the only population that showed absence of a haplotype (haplotype 7) and also the lowest frequency of haplotype 6, indicating lower African parental contribution than the Middle-Western populations. Contrary to our expectations, all populations showed low frequencies of haplotype 8, a characteristically European marker. The DRD2 TaqI haplotype is an AIM with great power of discrimination, therefore being recommended in the analysis of genetic mixture, but it would be necessary to expand the set of AIM markers to obtain a more concrete admixture pattern in those populations.