T-cell receptor alpha, delta, and gamma chain genes in insulin-dependent diabetes mellitus

We have studied the genotypic, haplotypic, and allelic distribution of germline Restriction Fragment Length Polymorphism (RFLP) of T-cell receptor (Tcr) alpha, gamma, and delta loci in 75 insulin-dependent diabetes mellitus (IDDM) patients and 84 healthy blood donors as control population. The restriction endonuclease PvuII produces three allelic fragments of Tcr C gamma (TcrCG) gene segment of 16, 13, and 11.3 Kb respectively. Our observations revealed that PvuII/TcrCG RFLP allelic distributions were not significantly different in the IDDM and the control group. However, 85% of IDDM patients carried HLA DR3 and/or DR4 haplotypes, and when comparing these patients with a second group of HLA DR3+ and/or DR4+ healthy individuals, the 11.3 Kb/PvuII fragment of TcrCG gene was found to be associated with IDDM patients (chi 2 = 11.4, P = 0.003). 54.9% of IDDM patients carried at least one 11.3 Kb allele vs. 21% in controls (chi 2 = 10.77, P = 0.004). No significant association was found between RFLP in Tcr, C alpha, C delta, V gamma 9 loci and IDDM.