Premature birth and low birth weight associated with nonautoimmune hyperthyroidism due to an activating thyrotropin receptor gene mutation

objective Nonautoimmune hyperthyroidism (NAH), a rare autosomal dominantly inherited condition characterized by nonremitting thyrotoxicosis and the absence of features of autoimmune thyrotoxicosis, can result from activating germline mutations in the thyrotropin receptor (TSHR) gene. We report clinical and genetic features of a new family with NAH, and highlight that premature delivery and low birth weight are important characteristics of this condition. patients and methods Thyrotoxicosis was diagnosed in two children at the ages 20 months and 4 years and in their father at the age of 9 years. Both children were born prematurely by Caesarian section at 33 and 30 weeks following early rupture of the membranes. Their birth weights were 1750 g (27th centile) and 790 g (