The study on mutations of the gene of extracellular domain of human thyrotropin receptor in the patients with thyroid diseases

Objective To define the sequence of the gene of extracellular domain of normal human thyrotropin receptor (hTSHR) and to investigate into the mutations of the gene in the patients with thyroid diseases. Methods Total RNAs were extracted from the thyroid tissue of four normal controls, twelve Graves' disease, four Hashimoto's thyroiditis and eleven nodular goiter patients. The extracellular domain of hTSHR genes were amplified by reverse transcription-polymerase chain reaction (RT-PCR) and sequenced with CEQ 2000 Genetic Analyzer. Results The normal controls and the patients with thyroid disease had the same gene sequences of the extracellular domain of hTSHR. No mutation was found, except a silent base exchange in exon 7 (Asn187) at 661 base, in which 20 samples were "T", 11 samples were "C", without changes of amino acid of the TSHR. Conclusions This study has not revealed mutations in the gene of extracellular domain of hTSHR. Other molecular pathogenetic mechanisms may be involved and more research is demanded.