RESUMO
To study thyroid hormone receptor β(THRβ)gene mutation in a pituitary-resistance to thyroid hormone syndrome family. The peripheral blood samples of the patient, his sister, parents, and 4 maternal relatives were collected. Then serum was isolated for detecting thyroid hormone levels with chemiluminescence immunoassay, and DNA was extracted for PCR, and 10 exons of THRβ gene were sequenced. The patient and his mother had the hyperthyroid symptom for many years and his mother with atrial fibrillation. The G→A heterozygous transition mutation was confirmed by exon sequencing at nucleotide 949 within exon 9 of THRβ gene in the patient and his mother, which was a missense mutation causing a substitution of Alanine to Threonine(A317T). No mutation was found in THRβ gene in other family members. This is the first Chinese family reported with pituitary thyroid hormone resistance syndrome caused by a A317T mutation in the thyroid hormone receptor β gene.