Objective: Genetic analysis of the TSH receptor gene in seven subjects with subclinical hypothyroidism (SH), in whom the diagnosis of autoimmune thyroid disease had been excluded by laboratory and instrumental techniques currently available. Patients: Three families where different members (2 children and 5 adults) affected by SH were studied. Genetic analysis: Genomic DNA was extracted from peripheral lymphocytes and the entire coding sequence of the TSHr gene was sequenced. pSVL-TSHr construct harbouring a Q8fsX62 insertion was obtained by site-directed mutagenesis. COS-7 cells transfected with wild-type and mutant receptor were used for binding studies, flow cytometry, and cyclic AMP (cAMP) determination. Results: A four base pair (bp) duplication in position 41 (41TGCAins), leading to a premature stop of translation at codon 62 (Q8fsX62), was found to be heterozygous in the proband, the father and the sister in Family 1. In Family 2 the proband and the sister were heterozygous for the mutation D410N. In Family 3 the proband and the father were heterozygous for the mutation P162A. After transfection in COS-7 cells, the mutant receptor Q8fsX62 displayed a low expression at the cell surface, and a reduced response to bovine TSH (bTSH) in terms of cAMP production. Conclusions: We identified TSH receptor mutations in seven members of three families with subclinical hypothyroidism. © 2007 The Authors.

Identification of TSH receptor mutations in three families with resistance to TSH

Perri A.;
2007-01-01

Abstract

Objective: Genetic analysis of the TSH receptor gene in seven subjects with subclinical hypothyroidism (SH), in whom the diagnosis of autoimmune thyroid disease had been excluded by laboratory and instrumental techniques currently available. Patients: Three families where different members (2 children and 5 adults) affected by SH were studied. Genetic analysis: Genomic DNA was extracted from peripheral lymphocytes and the entire coding sequence of the TSHr gene was sequenced. pSVL-TSHr construct harbouring a Q8fsX62 insertion was obtained by site-directed mutagenesis. COS-7 cells transfected with wild-type and mutant receptor were used for binding studies, flow cytometry, and cyclic AMP (cAMP) determination. Results: A four base pair (bp) duplication in position 41 (41TGCAins), leading to a premature stop of translation at codon 62 (Q8fsX62), was found to be heterozygous in the proband, the father and the sister in Family 1. In Family 2 the proband and the sister were heterozygous for the mutation D410N. In Family 3 the proband and the father were heterozygous for the mutation P162A. After transfection in COS-7 cells, the mutant receptor Q8fsX62 displayed a low expression at the cell surface, and a reduced response to bovine TSH (bTSH) in terms of cAMP production. Conclusions: We identified TSH receptor mutations in seven members of three families with subclinical hypothyroidism. © 2007 The Authors.
2007
Adolescent
Adult
Animals
Base Sequence
COS Cells
Child
Chlorocebus aethiops
Cyclic AMP
Female
Genotype
Heterozygote
Humans
Male
Molecular Sequence Data
Mutagenesis, Site-Directed
Pedigree
Receptors, Thyrotropin
Thyroid Hormone Resistance Syndrome
Thyrotropin
Thyrotropin-Releasing Hormone
Thyroxine
Transfection
Triiodothyronine
Mutation
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11770/307165
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