β-Globin haplotype analysis suggests that a major source of Malagasy ancestry is derived from Bantu-speaking Negroids

The origins of the inhabitants of Madagascar have not been fully resolved. Anthropological studies and preliminary genetic data point to two main sources of ancestry of the Malagasy, namely, Indonesian and African, with additional contributions from India and Arabia. The sickle-cell (β(S)) mutation is found in populations of African and Indian origin. The frequency of the β(S)-globin gene, derived from 1,425 Malagasy individuals, varies from 0 in some highland populations to .25 in some coastal populations. The β(S) mutation is thought to have arisen at least five times, on the basis of the presence of five distinct β(S)-associated haplotypes, each found in a separate geographic area. Twenty-five of the 35 Malagasy β(S) haplotypes were of the typical 'Bantu' type, 1 'Senegal' haplotype was found, and 2 rare or atypical haplotypes were observed; the remaining 7 haplotypes were consistent with the Bantu haplotype. The Bantu β(S) mutation is thought to have been introduced into Madagascar by Bantu-speaking immigrants (colonists or slaves) from central or east Africa. The Senegal β(S) mutation may have been introduced to the island via Portuguese naval explorers. This study provides the first definitive biological evidence that a major component of Malagasy ancestry is derived from African populations, in particular, Bantu- speaking Negroids. β(A) haplotypes are also consistent with the claim for a significant African contribution to Malagasy ancestry but are also suggestive of Asian/Oceanic and Caucasoid admixture within the Malagasy population.