A novel germline mutation in the TSH receptor gene causes non-autoimmune autosomal dominant hyperthyroidism.
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Alberti L, Proverbio MC, Costagliola S, Weber G, Beck-Peccoz P, Chiumello G, Persani L
A novel germline mutation in the TSH receptor gene causes non-autoimmune autosomal dominant hyperthyroidism.
Eur J Endocrinol. 2001 Sep;145(3):249-54.
- PubMed ID
- 11517004 [ View in PubMed]
- Abstract
OBJECTIVE: Clinical and genetic investigations were undertaken in a case of familial hyperthyroidism, with onset of thyrotoxic symptoms varying between childhood/adolescence. METHODS: Automatic sequence analysis was carried out of the TSH receptor (TSHR) gene. Functional studies were undertaken of mutant TSHR in transient expression experiments in COS-7 cells including the evaluation of cAMP accumulation and of protein expression by flow cytometry, as well as the calculation of specific constitutive activity (SCA). RESULTS: In four affected cases, the age of onset of thyrotoxic manifestations of non-autoimmune origin varied between 5 and 18 years. The disease transmission was typically autosomal dominant. TSHR gene sequence revealed the presence of a germline heterozygous substitution at codon 597 leading to the novel mutation V597F. This residue is located in the 5th transmembrane domain of the receptor protein in a critical region for membrane targeting and signal transduction. Functional studies of the V597F mutant indicate an 11-fold increase in SCA, associated with a reduction in receptor protein expression on the cytoplasmic membrane. CONCLUSIONS: Description was made of a family with non-autoimmune autosomal dominant hyperthyroidism carrying a novel mutation of TSHR leading to the increment in specific constitutive activity. Factors that may influence the clinical expression of TSHR germline mutations are discussed.