Association of HLA Antigen and Restriction Fragment Length Polymorphism of T Cell Receptor β- Chain Gene with Graves’ Disease and Hashimoto's Thyroiditis

HLA antigen phenotypes and BglII restriction fragment length polymorphism of T cell receptor β-chain (TCRβ) gene were analyzed in 61 patients with Graves’ disease and 50 patients with Hashimoto's thyroiditis. The antigen frequency of HLA-Bw46 in both Graves’ disease (23.0%) and Hashimoto's thyroiditis (24.0%) was significantly higher than that in normal population (8.0%), with relative risks (RR) of 3.45 [corrected P (Pc) < 0.009] and 3.66 (Pc < 0.02), respectively. Significantly increased frequency of HLA-B51 antigen was also found in Hashimoto's thyroiditis (40.0% vs. 16.3% in controls; RR, 3.42; Pc < 0.002). Hybridization of BglII-digested DNA with TCRβ probe revealed two alleles of 9.3 and 8.6 kilobases. The allele frequency of 8.6 kilobases in Graves’ disease (79%) and Hashimoto's thyroiditis (76%) was significantly higher (P < 0.01 and P < 0.05, respectively) than that in controls (64%). The frequency of homozygous state 8.6/8.6 was significantly increased in both Graves’ disease (62%) and Hashimoto's thyroiditis (60%) over that in controls (39%); the RR of 8.6/8.6 in Graves’ disease and Hashimoto's thyroiditis were 2.55 (P < 0.01) and 2.31 (P < 0.05), respectively. These results indicate that in Japanese subjects at least two loci are involved in the susceptibility to Graves’ disease and Hashimoto's thyroiditis, one related to HLA and another to TCRβ.