Familial hypothyroidism with autosomal dominant inheritance.

Three generations of a family with clinical and subclinical hypothyroidism caused by thyroid stimulating hormone (TSH) unresponsiveness are described. Findings were low to normal serum thyroxine, raised serum TSH, and low radioiodine uptake; goitre was notably absent. This family is the first evidence of an autosomal dominant mode of transmission of TSH unresponsiveness and may enable identification of the precise defect by genetic linkage study.