In an Eastern Hungarian population of patients, we sought to confirm an association with IgG heavy-chain allotypes (Gm) with Graves' disease. We found an increase in the phenotype fb (chi 2(1) = 4.7, p less than 0.05) among the patient group compared to controls. The influence of Ig-linked genes to Graves' disease susceptibility is, thus, dose-dependent. We found no interaction between fb homozygosity and HLA-DR3 positivity in Graves' disease susceptibility.