Abstract
Serum thyroxine-binding globulin (TBG), thyroxine, and thyrotrophin were estimated in members of a family with TBG deficiency. Xg(a) red cell antigen status was also studied. TBG deficiency appeared to be inherited as an X-linked condition. Four male members of the family showed absent TBG and seven heterozygous women showed intermediate TBG levels. Five informative phase known members of the family showed no recombination between Xg and TBG.