African gene flow to north Brazil as revealed by HBB*S gene haplotype analysis

Haplotypes linked to the HBB*S gene were analyzed in a sample of 260 chromosomes of Brazilian sickle cell anemia patients from the population of Belém, state of Pará, to evaluate if the present-day haplotype frequencies correlate as well as expected with historical information on the geographic origin of African slaves sent directly to Northern Brazil. The HBB*S gene haplotype distribution (66% Bantu, 21.8% Benin, 10.9% Senegal, and 1.3% Cameroon) is in agreement with those observed for other Brazilian populations regarding the highest proportion of the Bantu type, followed by the Benin type, but it differs significantly concerning the Senegal type as this haplotype is rare or absent in samples from other Brazilian regions already studied. In addition, our results are in accordance with historical records that establish that about 90% of the slaves sent to Northern Brazil were from Angola, Congo, and Mozambique, where the Bantu haplotype predominates, in contrast to 10% of slaves from Senegambia, Guine-Bissau, and Cape Verde, where the Senegal haplotype is the most common. On the other hand, the observed frequency of the Benin haplotype in Belém was much higher than that expected by historical data. This fact corroborates the suggestion that the high prevalence of the Benin type in Belém is due to domestic slave trade and later internal migrations, mainly from the Northeast, since there are no historical records of direct slave trade from Central West Africa to North Brazil.