The aetiology of Type I diabetes

The aetiology of Type 1 diabetes involves both genetic and environmental fa ctors. The genes implicated are 'susceptibility genes', which modify risk. Individual susceptibility genes may not be required and are not sufficient for disease development. The strongest genetic risk component is encoded wi thin the major histocompatibility complex (MHC) and is designated IDDM1. Th e HLA-DQ genes contribute to the risk, but so may other MHC-encoded genes. The susceptibility encoded by IDDM2 refers to a variable number of tandem r epeats in the insulin gene region. Many other genomic regions have been des ignated as susceptibility intervals potentially containing candidate genes. Environmental factors appear to be important in disease expression in eith er a causative or a protective role. Epidemiological data indicate that suc h factors operate from early in life. Viral infection(s) may have a disease -initiating and/ or accelerating effect. A potential diabetogenic role for cows' milk protein remains unconfirmed. Further research is necessary to el ucidate fully the aetiological factors involved and how they interact.