The molecular determination of HLA-Cw alleles in the Mandenka (West Africa) reveals a close genetic relationship between Africans and Europeans.

HLA-Cw alleles were determined by high-resolution polymerase chain reaction-sequence-specific oligonucleotide probe (PCR-SSOP) oligotyping in a sample of 165 Mandenka, a population from Eastern Senegal previously analysed for A/B and DRB/DQB polymorphisms. A total of 18 Cw alleles were identified, with Cw0401/5 and 1601 accounting for a combined frequency of 36%. A comparison of Cw allele frequencies among several populations of different origins, Mandenka, Swiss, English, Ashkenazi Jews from the UK and Japanese, reveals a high genetic heterogeneity among them, but also a much closer relationship between Mandenka, Europeans and Ashkenazi than between any of these populations and Japanese. Cw0501, Cw0701 and Cw1601, among others, appear to be restricted to the European and African populations. Many B-Cw haplotypes exhibit a significant linkage disequilibrium in the Mandenka, among which B3501-Cw0401 and B7801-Cw1601, formed by the most frequent B and Cw alleles, and B5201-Cw1601, B5702-Cw18 and B4410-Cw0401, not yet observed in other populations. B3501-Cw0401 is found with similar frequencies in Europeans. The results possibly support a close historical relationship between Africans and Europeans as compared to East Asiatics. However, the HLA-Cw frequency distributions are characterised by an excess of heterozygotes, indicating that balancing selection may have played a role in the evolution of this polymorphism.