[Mo66, a new allele of the HLA-B locus. Preliminary note (author's transl)].

Mo66 is an allele of the HLA-B locus, which is demonstrated by HLA typing of 2 000 unrealted individuals and the members of eight informative families. Mo66 is a rare antigen, with a frequency of 0.65 % in the Languedocian population. Mo66 shows a strong association desequilibrium with HLA-A3. The identification of Mo66 is difficult, without a monospecific serum, because this antigen is united by cross-reactions above all with HLA-B13, but also with HLA-Bw40, HLA-B27, HLA-B12 and HLA-B7. The presence of an anti-Mo66 antibody in some apparently anti-HLA-B27 monospecific sera can provoke some errors in the diagnosis of ankylosing spondylitis and related diseases.