Genes and diabetes mellitus.

Susceptibility to both insulin-dependent and non-insulin dependent diabetes mellitus is determined to a substantial extent by genetic factors. These probably interact with an environmental trigger to induce expression of the disease state. Significant progress has been made in defining these genetic factors in IDDM. The major contribution comes from a gene or genes within the HLA region, on the short arm of chromosome 6, at least one of which lies close to or within the DQ subregion. Other loci also contribute, most notably the insulin gene, or another closely linked gene on the short arm of chromosome 11, and possibly the T-cell receptor and immunoglobulin genes. In contrast very little is known for NIDDM and such associations as have been described remain controversial.