A Novel TSHR Gene Mutation in a Family with Non-autoimmune Hyperthyroidism

Background

Familial non-autoimmune hyperthyroidism is a rare disorder characterized by the absence of thyroid autoimmunity, particularly TSH receptor antibody [TRAb].

Objective

The aim of this study was to describe a novel TSHR mutation identified in a family of two siblings and their father.

Methods

Two siblings presented for endocrine assessment at ages 7 and 14 years with mild T3 toxicosis, and the father presented at 30 years of age with non-autoimmune thyrotoxicosis. Both siblings were treated with oral antithyroid therapy to achieve reasonable symptom control and thyroid function normalization. The father was treated with oral antithyroid therapy, radioactive iodine, thyroidectomy, and thyroid replacement therapy. Peripheral blood DNA was extracted from both affected siblings and father. Mutation analysis of TSHR was carried out by PCR and Sanger sequencing of both strands of the extracted DNA.

Results

Both siblings and their father were heterozygous for the missense TSHR variant c.1855G>C, p.[Asp619His], in exon 10.

Conclusions

This novel TSHR variant is associated with T3 toxicosis during childhood. Therefore, early identification and treatment may improve patient outcomes.

Recurrent, refractory hypokalemia as a diagnostic clue to thyrotoxic periodic paralysis in a patient with acute kidney injury and suspected Guillain-Barre syndrome

When clinical presentation is atypical, especially in a non-Asian population, the finding of recurrent and refractory hypokalemia can serve as a key diagnostic clue for timely diagnoses and management of thyrotoxic periodic paralysis. In suspected cases, complete thyroid laboratory panel should be measured so that T3 toxicosis is not missed.