Congenital thyroxine binding globulin deficiency: incidence and inheritance.

Ninety-nine cases of thyroxine binding globulin (TBG) deficiency (90 males and 9 females) were identified among low-T4 infants after newborn hypothyroid screening. The data indicate that inherited TBG deficiency occurs in at least 1:5,000 newborns (1:2,800 males) and that mild and more pronounced forms are found in approximately equal proportions. Genetic analysis indicates that X-linked inheritance is the usual mode with no suggestion of autosomal inheritance.