HLA AND DISEASE - PREDICTIONS FOR HLA HAPLOTYPE SHARING IN FAMILIES

Abstract

An analysis of published data on the segregation of HLA haplotypes in families with more than 1 individual affected with insulin-dependent diabetes mellitus or multiple sclerosis yields 3 conclusions. In families with unaffected parents, affected sib pairs are much more often HLA haplotype identical in sibships with 2 affected sibs than in sibships with 3 or 4 affected sibs (P < 0.01). In families with unaffected parents with HLA 1/2-identical affected sibs, well siblings more often receive the single haplotype not found in the affected sibs than is expected by chance (P < 0.05). In families with 1 affected parent, well siblings of affected individuals may share with the affected child a haplotype from the unaffected parent < 50% of the time (P < 0.10). In some non-Mendelian, familial, HLA-associated diseases more than 1 gene may contribute to susceptibility to the disorder.