Thyroid hormone resistance due to a novel THRß mutation.

Dear Editor, Resistance to thyroid hormone (RTH) is a syndrome of reduced responsiveness of target tissues to thyroid hormone. Patients with thyroid hormone resistance have elevated free triiodothyronine (fT3) and/or free thyroxine (fT4) with inappropriately normal or elevated thyroid stimulating hormone (TSH). It is a diagnosis to consider in newborns presenting with abnormal thyroid function. We report a case of a 1 year 8 months old boy with RTH who had a novel mutation of the THRβ gene. This mutation is, to the best of our knowledge, the fi rst such mutation reported in Singapore.