Beta-globin gene cluster haplotypes as evidence of African gene flow to the northeastern coast of Venezuela.

In order to study the origin of mutation HBB*S in Sucre and Anzoátegui states and the genetic affinities of these Venezuelan populations with other human groups, the beta-globin gene cluster haplotypes were determined for 28 sickle cell and/or S-beta thalassemia patients and for 37 individuals with normal hematological parameters. Bantu, Benin, Senegal, and atypical haplotypes were identified in 50%, 36%, 2%, and 12% of the HBB*S chromosomes, respectively. Similar results have been published for Venezuelan patients from the central states, but a different trend is shown in a publication based on a group of patients from different regions of the country. For HBB*A, haplotype 2 (+ - - - -), characteristic of non-African groups, was the most common (39%), followed by haplotype 3 (- - - - +) of African origin, and haplotype 6 (- + + - +), also typical of non-Africans. The results reveal a high level of admixture of the Sucre-Anzoátegui population. The importance of specific conditions which have acted differently in the Venezuelan populations, such as founder effect, genetic drift, isolation, and endogamy are discussed. Genetic distances between the Sucre-Anzoátegui sample and several other human populations calculated on the basis of the HBB*S and HBB*A haplotypes revealed similar results, the closest genetic relationships being observed in relation to Bantu-speaking groups. These results confirm the utility of the beta-globin haplotypes for population studies and contribute to knowledge of the Venezuelan gene pool.