HLA class-I diversity in Cameroon: evidence for a north-south structure of genetic variation and relationships with African populations.

HLA class I diversity (loci A, B and C) was analysed in four populations, two from North Cameroon (Podokwo and Uldeme) and two from South Cameroon (Ewondo and Bamileke). Northern and southern Cameroon populations show a substantial genetic diversity in terms of haplotype sharing and genetic distances, even despite the low percentage of variance due to differences among populations evidenced by analysis of molecular variance. The signals of differentiation among populations are consistent with their linguistic affiliation, and support previous evidence, based on autosomal microsatellites and protein loci, which has shown that the complex pattern of genetic variation of Cameroon can in part be described by contrasting the northern and southern part of the country. Looking at our results in the more general framework of HLA diversity in sub-Saharan Africa, it turns out that the Podokwo and Uldeme show some genetic links to populations of the southern western branch of the Sahel corridor, while their high frequency of A*02 and C*04 alleles is congruent with previously hypothesised introgression of non-sub-Saharan alleles. On the other hand, signals of shared ancestry between the Bamileke and Ewondo and the Bantu speakers from central and southern Africa were detected.