HLA antigen segregation analysis in multiple sclerosis (MS) families.

HLA antigen segregation analysis was performed in 38 families with a total of 52 multiple sclerosis (MS) patients including 14 families with 2 affected sibs. HLA-A3 and especially B7 occurred more frequently in familial MS cases (propositi) (A3: 42.9%, B7: 64.3%) than in non-familial cases (A3: 35.8%, B7: 35.3%). As could be expected from the increased phenotype frequencies of A3 and B7, the haplotype A3-B7 showed a disturbed segregation among the MS patients but not among their healthy sibs. A second haplotype, A1-B8, was found more frequently than expected among the MS patients but also among their unaffected sibs. These data may suggest increased MS susceptibility associated with the haplotype A3-B7 and, conversely autoimmune or protective properties associated with A1-B8 in MS patients and their healthy sibs, respectively.