FAMILIAL THYROXINE-BINDING GLOBULIN DEFICIENCY ASSOCIATED WITH HYPERTHYROIDISM

A 24-year-old woman with familial thyroxine-binding globulin (TBG) def iciency associated with hyperthyroidism is reported, Thyroid-stimulati ng hormone (TSH)-binding inhibitor immunoglobulin (TBII) was negative, whereas thyroid-stimulating antibody (TSAb) was positive, Serum thyro xine-binding globulin (TBG) levels were extremely low, and remained lo w even after the normalization of thyroid function with methimazole (M MI) treatment. The serum TBG level of the mother of patient was also b elow the normal lower limit. Genetic analysis revealed single nucleoti de deletion, common among Japanese with complete TBG deficiency (TBG-C D), from the allele-specific amplification of the TBG genes of the pat ient.