No interaction between HLA and immunoglobulin IgG heavy chain allotypes in early onset type 1 diabetes

Immunoglobulin heavy and light chain genes are often discussed as susceptibility genes for insulin dependent (type 1) diabetes mellitus (IDDM) in addition to HLA-DR3 and DR4. Accordingly we analysed 175 unrelated patients for an interaction between immunoglobulin allotype antigens (Gm) and HLA. While DR3 and DR4 antigens and DR3/DR4 heterozygotes occur significantly more often among diabetics than among normal controls, their Gm allotype frequencies are very similar. An interaction between special Gm allotypes and phenotypes, on the one side, and DR3, DR4 or DR3, 4 on the other side could not be demonstrated.