Human population genetics of Comoros islanders: Alu polymorphisms and the peopling of the three major islands

Abstract

BackgroundThe Comoros archipelago is located in the Indian Ocean between Madagascar and the East African coast. Their geographic localization yielded an admixed population of sub-Saharan African, Middle Eastern, and Austronesian influences. AimTo evaluate the genetic diversity whithin and between the three major islands (Grande Comore, Anjouan, and Moheli) using Alu polymorphisms, and to assess their genetic relationships with Africans, Middle Easterns and South Eastern Asians. - To investigate the peopling of these islands. Subjects & methods18 polymorphic Alu insertions have been typed in 295 unrelated individuals from Comoros archipelago: Grande Comore (122), Anjouan (95), and Moheli (78). The data were analyzed for intra and inter-population genetic variations. ResultsThe Comoros archipelago showed a high level of intra-population genetic diversity and a strong genetic homogeneity between the three islands (FST = 0.0037). The MDS analyses showed higher affinity between the Comorians and nerby sub-Saharans. Admixture estimates highlight a high sub-Saharan component in the genetic background of the current Comorians with some Middle Eastern and Southeast Asian contributions. ConclusionThe Alu polymorphisms used in the present study provided interesting results about the peopling of the Comoros. They showed a high level of genetic diversity probably shaped by successive migratory waves from the three historically related regions and underlined also a high genetic homogeneity among the three islands, probably originated by their common demographic history and/or the geographic proximity.