Endocrine Abstracts

Nonautoimmune hyperthyroidism (NAH) due to activating mutation of the TSH receptor (TSHR) gene is extremely rare. We report 4 unrelated families with NAH experienced for the last two years in Kumamoto Prefecture, Kyushu, Japan. TSHR gene mutation site of these four families are all the same: p.Asn406Ser (heterozygous). Thyroid functions observed in these families were subclinical hyperthyroidism or overt hyperthyroidism except for one case with euthyroidism. Thyroid autoantibodies (TRAb, TPOAb, TgAb) were all negative.

[Family 1] We have already reported about this family (Clin Endocrinol (Oxf).2011).

[Family 2] 29-year-old male showing hyperthyroidism with large goiter(estimated weight:84.2g).

[Family 3] 59-year-old male showing subclinical hyperthyroidism with with nodules in the thyroid gland which was diagnosed as papillary carcinoma.

[Family 4] 40-year-old female showing subclinical hyperthyroidism with nodule in the thyroid gland which was diagnosed as papillary carcinoma. Her son had overt hyperthyroidism.

[Conclusion] This mutation(p.Asn406Ser) has not been found outside the southern Kumamoto Prefecture. Many pedigrees of NAH may have accumulated in this area.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.