Genetic linkage between Bf S0.7 (Bf S1) and HLA-Bw50

Two hundred and one unrelated French Basque individuals were studied for HLA-A, B, C, DR and Bf polymorphisms. The results show that the Bf S0.7 (Bf S1) variant, which is known to be associated with HLA-Bw21, presents a highly significant linkage disequilibrium with a subtypic specificity, i.e., Bw50 (delta = 0.0123, delta S=100%, P less than 10(-8)). As neither Bf S0.7 variant nor Bw50 antigen is found in Mongoloid populations, it is suggested that in evolutionary terms, the Bf S0.7 mutation is a more recent event than the HLA-Bw21 split.