Alu insertion polymorphisms in four ethnic groups from northern Ivory Coast

Abstract

Patterns of genetic variation among geographically and ethnically diverse African populations have been under-represented in human genetics studies despite their importance for describing the evolutionary history of modern human populations. We conducted a study on 133 individuals, belonging to four northern Ivorian ethnic groups, based on the allele distribution of 11 Alu insertion loci, and compared the results with other African populations. All loci proved to be polymorphic in all ethnic groups, with the exception of HS2.43 and HS3.23, which were fixed for the absence and for the presence, respectively, of the Alu element. No significant departure from Hardy–Weinberg equilibrium was found among polymorphic loci, except for TPA25 loci in the Baoulé and Bété groups. Average heterozygosity (0.193 ± 0.042) was lower than that observed for the same loci in other African populations and the F_ST value among ethnic groups for all loci was also notably low (0.0456). Multidimensional scaling analysis clearly separated Ivorians from other African samples, while in the neighbor-joining tree this population represented a basal branch of the tree, close to the hypothetical ancestral lineage. The picture emerging from our analyses reveals a conspicuous genetic homogeneity among Dioulà, Sénoufos, Boulè, and Bètè despite their sociocultural subdivision. Moreover, this northern Ivory Coast population, as a whole, turns out to be relatively isolated from the other African populations, possibly as a consequence of local patterns of population history, limited migration rates, and random genetic drift.