[Genetic susceptibility of insulin-dependent diabetes]

Type I Insulin-Dependent Diabetes Mellitus (IDDM) is an autoimmune disease characterised by the destruction of pancreatic Beta cells. There is an evidence for a contribution of genetic factors to the development of the disease and it is widely documented that HLA antigens contribute to the disease susceptibility. HLA-DR3 and HLA-DR4 associations have been firstly described in Caucasian. Recent studies at the gene level have elucidated this HLA association more precisely, pointing out the prominent role of HLA-DQ locus genes. The hypothesis has been proposed that some critical amino-acid at position 57 of DQ Beta chain and at position 52 of DQ Alpha chain both contribute to disease susceptibility. According to the functional role of HLA class II molecules, these particular residues may affect the antigen binding and T cell recognition and therefore contribute to the triggering of the pathological auto-immune response.