Haplotypes of alpha-globin gene regulatory element in two Brazilian native populations.

The alpha-major regulatory element (alpha-MRE), located 40 Kb far upstream of the alpha-globin gene cluster on chromosome 16, is involved in the regulation of human alpha-globin genes expression. The activity of this element is restricted to a 350-bp fragment in which several nuclear protein binding sites have been identified. This element is genetically polymorphic and different haplotypes, named A-F, have been determined in seven populations of Europe, Africa, Asia, and Oceania. We describe here the alpha-MRE haplotypes found in native Indians from two nonmiscegenated tribes of the north region of Brazil, in Amazonia, the Parakanã and the Xikrin. The A haplotype was predominant in both (70% and 87%, respectively), followed by the B haplotype (30% and 13%, respectively). The haplotype frequency distribution among the Parakanã was similar to that reported for Indonesians and Southeast Asian populations, while the distribution among the Xikrin showed higher similarity to that observed in Indonesians. These results corroborate the existence of genetic affinities between Brazilian Indians and Southeast Asian and Oceanic populations. This was the first investigative work on the alpha-MRE polymorphism in South American native populations in general or Brazilian native populations in particular.