ABSTRACT
Thyrotropin receptor(TSHR) mutations must be considered when congenital hyperthyroidism has persisted, but there has been no evidence for autoimmunity. TSHR mutations leading to constitutive activation of the thyroid gland were identified as the molecular cause of autosomal dominant nonautoimmune hyperthyroidism and sporadic congenital hyperthyroidism. We report two cases of hyperthyroidism caused by germline TSHR mutation who presented with exessive sweating and no evidence of autoimmune thyroid disease. They were brothers and their mother had undergone thyroidectomy because of hyperthyroidism. Direct sequencing of the polymerase chain reaction-amplified exon 10 of the TSHR genomic DNA revealed a transition of GCT to GTT, resulting in an exchange of alanine 627 to valine in the patients and their mother. This might be a novel mutation or polymorphism, but we did not perform any functional gene study. But considering the clinical profiles, we can conclude that hyperthyroidism of these two brothers might come from the point mutation described above.