Clinical and pathological significance of sibling Graves' disease

The clinical picture and serum antithyroid antibodies in 16 pairs of siblings with Graves' disease were compared with an age and sex matched group of 32 patients with Graves' disease who did not have a family history of any thyroid disease (control patients). There was a significant difference in frequency and mean titres of antibodies to thyroglobulin between sibling patients. (positive 76.0%) and control patients (positive 40.0 %), but not in microsomal antibodies (sibling; positive 92.0%, control; 92.0%). There were no significant differences in the mean values of 24 h 131I-thyroidal uptake, serum T3U, serum T4 and T3 concentrations before treatment between the two groups. Lymphoid follicles and degeneration of the epithelia were more often found in the thyroid glands of sibling patients than in those of the control patients, when 32 (16 sibling, 16 control) thyroid glands from the same groups in the clinical study, including antibody series, were examined pathologically after subtotal thyroidectomy for Graves' disease. Moreover, there was a strong tendency to increased lymphocyte and plasma cell infiltration in the thyroid glands of sibling patients with Grave's disease. The findings might indicate that Graves' disease is closely related to Hashimoto's thyroiditis, especially in sibling patients with Graves' disease.