DRB genotyping supports recessive inheritance of DR3-associated susceptibility to insulin-dependent diabetes mellitus.

The mode of inheritance of HLA-associated susceptibility to insulin-dependent diabetes mellitus was investigated by the antigen genotype frequency among patients method in a white Caucasian population and a North Indian Asian population.DR genotypes were determined by DRB/DQB RFLP analysis.In white Caucasians, simple recessive and simple additive inheritance of a single HLA-associated disease susceptibility allele were rejected (P less than .025 and P less than 10(-6), respectively).The data were compatible with a three-allele model of disease susceptibility.In North Indian Asians, simple additive inheritance was rejected (P less than 10(-6)).The observed genotype frequencies were compatible with a single DR3-associated disease susceptibility allele which is inherited recessively.These data show that study of DR genotypes in populations of different ethnic origins may further the understanding of inherited susceptibility to insulin-dependent diabetes mellitus.