A mutation in thyroid hormone receptor beta causing "resistance to thyroid hormone" in a neonate.

Resistance to thyroid hormone (RTH) is an inherited syndrome characterized by reduced tissue responsiveness to thyroid hormones. The main defects are due to mutations in thyroid hormone receptor beta (TRbeta). A male, term neonate was admitted because of indirect hyperbilirubinemia and polycythemia. Physical examination revealed ophtalmopathy. High serum T 4 with unsupressed thyroid stimulating hormone (TSH) levels suggested RTH. In this presented case, A317T mutation was detected on exon 9 of the TRβ-1 gene and precise diagnosis had been confirmed with genetic testing. In neonates and infants exhibiting hypo or hyperthyroidism features with increased circulating levels of thyroid hormones with a normal or increased serum TSH concentration should raise the suspicion of RTH.