Distribution of HLA-DRB1, -DQA1 and -DQB1 alleles and DQA1-DQB1 genotypes among Norwegian patients with insulin-dependent diabetes mellitus.

We have studied 87 unrelated Caucasian insulin-dependent diabetes mellitus (IDDM) patients and 181 healthy controls by oligotyping for 20 DRB1, eight DQA1 and 13 DQB1 alleles, and established their DR-DQ haplotypes and DQ genotypes. An increase of DRB1 alleles encoding DR4 was found among IDDM patients, but the distribution of DR4 subtypes did not differ among DR4-positive IDDM patients and controls. The frequency of certain DRB1-DQA1-DQB1 haplotypes and DQA1-DQB1 genotypes was significantly increased among IDDM patients. Taken together, the data suggest that IDDM is primarily associated with several (at least five) different DQ alpha beta heterodimers.