Heterogeneity of insulin-dependent diabetes-new evidence.

We have performed complex segregation and linkage analysis in 182 families with at least one insulin-dependent diabetic proband. All families were typed for B histocompatibility (HLA) antigens and 118 for DR. The recessive model fit the data best, with maximum likelihood estimates of recombination between HLA DR and the susceptibility factor of 0.019. Substantial heterogeneity was suggested, with smallest estimated recombination for pedigrees whose probands have two high-risk DR alleles. The results are compatible with a strong, tightly HLA-linked susceptibility factor and evidence for additional non-HLA linked genetic factor(s).