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The detection of somatic mutations of thyrotropin receptor gene in fine needle biopsy samples from thyroid nodules
A Syrenicz1, G Kurzawski, A Ciechanowicz
1Department of Endocrinology, Hypertension and Metabolic Diseases, Pomeranian Academy, 71-455 Sczecin, Poland.
Objective:
To evaluate the detection possibility of TSH receptor gene mutation within the third cytoplasmic loop and the sixth transmembrane domain in the cytological material obtained by means of fine needle biopsy of autonomous and non-autonomous nodules.
Methods:
The study has been carried out in 16 women with goitre showing no clinical signs of hyperthyroidism. According to the thyroid scintigraphy and serum level of thyrotropin (TSH) the patients were divided into two groups: 1. 6 patients with autonomous nodules; 2. 10 patients with non-autonomous nodules. Genomic DNA has been isolated from the cytological material and the peripheral blood nuclear cells in order to confirm possible somatic character of TSH receptor gene mutations. DNA has been amplified in polymerase chain reaction (PCR) with the use of a specific pair of primers. Purified PCR products have been subjected to further automatic sequencing.
Results:
Among 6 autonomous nodules tested one heterozygotic somatic mutation of adenine for cytosine at 1804 nucleotide of TSH receptor gene was detected. This mutation resulted in the change of threonine (codon ACC) at 632 position of TSH receptor protein for proline (codon CCC). Among the non-autonomous nodules one heterozygotic somatic mutation of adenine for cytosine at 1870 nucleotide of receptor TSH gene has been detected. From this mutation followed the change of lysine (codon AAG) at 624 position of the polypeptide chain for glutamine (codon CAG) followed as a consequence.
Conclusions:
We emphasize the validity of fine needle biopsy in the detection of somatic mutations in the TSH receptor gene. For the first time the somatic mutation in the TSH receptor gene in a non-autonomous nodule has been reported.
Insights
Fine needle biopsy successfully detected TSH receptor gene mutations in both autonomous and non-autonomous thyroid nodules. This study reports the first somatic mutation in the TSH receptor gene within a non-autonomous nodule.
Area of Science:
- Endocrinology
- Molecular Biology
- Genetics
Background:
- Thyroid nodules are common, and understanding their genetic basis is crucial for diagnosis and treatment.
- The TSH receptor gene plays a key role in thyroid function and nodule development.
Purpose of the Study:
- To investigate the presence of TSH receptor gene mutations in cytological samples from thyroid nodules.
- To evaluate the utility of fine needle biopsy for detecting these mutations.
Main Methods:
- Genomic DNA was isolated from fine needle biopsy samples of 16 women with goiter.
- Polymerase chain reaction (PCR) and automatic sequencing were used to analyze the TSH receptor gene.
- Patients were categorized into autonomous and non-autonomous nodule groups based on clinical and biochemical data.
Main Results:
- A somatic mutation (A to C at nucleotide 1804) was found in one autonomous nodule, altering threonine to proline at position 632.
- A somatic mutation (A to C at nucleotide 1870) was identified in one non-autonomous nodule, changing lysine to glutamine at position 624.
- These mutations occurred in the third cytoplasmic loop and sixth transmembrane domain of the TSH receptor.
Conclusions:
- Fine needle biopsy is a valid method for detecting somatic mutations in the TSH receptor gene.
- This study reports the first instance of a somatic mutation in the TSH receptor gene within a non-autonomous thyroid nodule.