Origin of Hb A′2 (Hb B2) [δ16(A13)Gly→Arg (GGC→CGC)]

On a field trip to the Dogon country (le Pays Dogon) in central Mali, we detected a high frequency of the Hb A2 abnormality, reaching higher numbers among blacksmiths (up to 12.4%) living in the same villages. In this report, by direct nucleotide sequencing and employing a polymerase chain reaction-restriction fragment length polymorphism approach, we show that the Hb A2 variant observed in the Dogon population is indeed Hb A′2, also called Hb B2, and that in all of the cases the 2 abnormal δ-globin gene is linked to a unique haplotype. The same haplotype was found linked to Hb A′2 in the Herero population belonging to the South African Bantu-speaking Blacks from Namibia. Although the unique origin of this mutation in Africa is a possibility, a recurrent mutational event cannot be excluded because the linked β cluster haplotype is one of the two major haplotypes found in all African populations. A study of populations from other regions of Africa is required to clarify this issue.