No abstract

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.

Summary We studied 201 unrelated French Basque individuals for HLA and Bf polymorphisms. The haplotypes of eighty‐seven of them were deduced from family studies. The results show the frequency of the Bf F1 allele (0.1393) which is the highest one currently reported. They confirm the high frequencies of HLA‐Aw19.2 and B18 previously reported in that population and show that a whole haplotype with strong linkage disequilibria, namely Aw19.2, Cw5, B18, Bf F1, DRw3 is frequent. On the other hand, the gene frequency of Bf S is decreased (0.5497) as compared with the other European Caucasoïd populations, while a slight increase in the Bf F gene frequency (0.2960) appears. These results point out that it is of importance to consider the genetic background in choosing the population where linkage disequilibria are to be studied.