The immunogenetics of insulin-dependent diabetes.

Insulin-dependent (type 1) diabetes mellitus (IDDM) is a multifactorial disease with a strong genetic component. The majority of the genetic component can be explained by associations between IDDM and genes in the major histocompatibility complex (MHC). The best single marker for IDDM is based on amino acid polymorphism of the HLA-DQ gene. Current evidence, however, indicates that the MHC susceptibility to IDDM is determined by a combination of HLA class I, II and III genes contained on HLA haplotypes. A non-MHC genetic component to IDDM also exists. To date, the most consistent association is between IDDM and markers of the insulin gene locus.