Lack of association of T cell receptor beta-chain constant region polymorphism with insulin-dependent diabetes mellitus in Finland.

Allelic polymorphism in the T cell receptor constant beta-chain gene region has been reported to be associated with autoimmune diseases, including insulin-dependent diabetes mellitus (IDDM). The present analysis of 164 children and adolescents with IDDM and 193 controls for BqlII polymorphism using a TcR-C beta cDNA probe revealed two allelic restriction fragments with sizes of 10.5 kb (U) and 9.6 kb (L). No particular association was observed between the RFLP genotypes and IDDM (UU 27% versus 31%; UL 53% versus 52%; and LL 20% versus 17%, in diabetic subjects and controls, respectively), nor were any differences found between patients with various HLA risk antigens. The frequency of heterozygotes was 52% in 63 DR3-positive diabetic subjects and 53% in 73 DR3-negative ones. The results do not support any involvement of the TcR constant region genes in susceptibility to IDDM.