Close genetic linkage between diabetes mellitus and kidd blood group

27 polymorphic genetic markers were analysed for possible linkage with insulin-dependent diabetes mellitus (IDDM). The data set contained 71 families with at least one affected member each. Under three different genetic models for IDDM, evidence was found for linkage between the disease and two distinct sets of marker loci: three markers on chromosome 6 (HLA, properdin factor B, and glyoxalase-1), and the Kidd blood group locus. The families apparently do not fall into two groups, one exhibiting linkage to the HLA complex and the other to the Kidd locus. Thus, two distinct disease-susceptibility loci may be involved in the inheritance of IDDM.