Previous studies of HLA and Hashimoto's thyroiditis have shown weak associations between the disease and various HLA-DR antigens.
Objective: To define better the contribution of HLA class II alleles to susceptibility to Hashimoto's thyroiditis.
Design and measurements: Comparison of HLA-DRB, DQA and DQB restriction fragment length polymorphisms in patients with Hashimoto's thyroiditis and control subjects, and meta-analysis of this and other published studies.
Patients: Fifty Caucasian patients with Hashimoto's thyroiditis and 93 racially-matched control subjects.
Results: A 4.6 kb Taq 1 DQA restriction fragment length polymorphism occurred in 60% of patients compared with 35.5% of controls, Pc < 0.025. No other restriction fragment length polymorphism was significantly associated with the disease. Meta-analysis of several studies demonstrated weak, positive associations between the disease and DR3 and DR4. An association with DR5 was not significant.
Conclusions: DR antigens are unlikely to determine disease susceptibility directly. These findings indicate that any contribution of HLA genes to inherited susceptibility to Hashimoto's thyroiditis is small and requires confirmation in family studies.