GRAVES' DIEASE AND HASHIMOTO'S THYROIDITIS IN MONOZYGOUS TWINS

Abstract

ABSTRACT Monozygous twins and their family were studied. One twin had Graves' disease and the other had Hashimoto's thyroiditis. Their mother had Hashimoto's thyroiditis and their maternal grandmother and maternal great aunt had hyperthyroidism. Thyroid biopsies were obtained in each of the twins and showed changes of Graves' disease and Hashimoto's thyroiditis, respectively. High concentrations of anti-thyroid microsomal and anti-thyroglobulin antibodies were present by competitive protein binding assay, but LATS was absent in the twins and their mother. The occurrence of Graves' disease and Hashimoto's thyroiditis in monozygotic twins supports the concept of a common genetic aetiologic factor in the basic pathogenesis of these two diseases; however, the expression of this factor is variable, acquired, and, at least in part, genetically independent.