High prevalence of TSHR/Gsα mutation-negative clonal hot thyroid nodules (HNs) in a Turkish cohort

Relationship between TSHR, BRAF and PIK3CA gene copy number variations and thyroid nodules

PURPOSE

This study aims to investigate the relationship between the TSHR, BRAF, and PIK3CA gene copy number variations (CNVs) and thyroid nodules by analyzing gene CNVs, and to explore the interaction between iodine status and the above genes CNVs in the occurrence of thyroid nodules.

METHODS

Three hundred and ninety-five subjects were selected from 3 regions with different iodine status in Shanxi Province of China, including 192 patients with thyroid nodules and 203 healthy controls. The basic information about subjects had been obtained through a questionnaire. B ultrasound was utilized to check thyroid nodules. Blood and urine samples were harvested to detect the thyroid function and urinary iodine concentration. Real-time quantitative polymerase chains reaction (RT-PCR) served to detect CNVs in DNA from human blood.

RESULTS

There was an association between TSHR gene CNV and thyroid nodules (χ² = 8.403, P = 0.004). The prevalence of BRAF and PIK3CA gene CNVs was not statistically significant between the case group and the control group. Differences in the TSHR gene CNV rates for cases of the 3 areas were statistically significant (χ² = 10.072, P = 0.007). No statistical difference in the prevalence rates of the 3 genes CNVs between diverse characteristics of thyroid nodules was observed. UIC > 300 μg/L (OR = 1.74, 95% CI: 1.02-2.96, P = 0.041) and TSHR gene CNV (OR = 3.53, 95% CI: 1.40-8.92, P = 0.008) were risk factors for thyroid nodules. There was no significant interaction between the UIC and the examined genes CNVs.

CONCLUSIONS

TSHR gene CNV and high urinary iodine levels can increase the risk of thyroid nodules. But the interactions between the 3 above genes CNVs and iodine nutrition were not found in the occurrence of thyroid nodules.

Sensitive Sequencing Analysis Suggests Thyrotropin Receptor and Guanine Nucleotide-Binding Protein G Subunit Alpha as Sole Driver Mutations in Hot Thyroid Nodules

Background: Constitutively activating mutations in the thyrotropin receptor (TSHR) and the guanine nucleotide-binding protein G subunit alpha (GNAS) are the primary cause of hot thyroid nodules (HTNs). The reported prevalence of TSHR and GNAS mutations in HTNs varies. Previous studies show TSHR mutations in 8-82% of HTNs and GNAS mutations in 8-75% of HTNs. With sensitive and comprehensive targeted next-generation sequencing (tNGS), we re-evaluated the prevalence of TSHR and GNAS mutations in HTNs. Methods: Samples from three previous studies found to be TSHR and GNAS mutation negative were selected and re-evaluated using high-resolution melting (HRM) PCR. Remaining mutation negative samples were further reanalyzed by tNGS with a sequencing depth between 3000 × and 10,000 × . Our tNGS panel covered the entire TSHR coding sequence along with mutation hot spots in GNAS. Sequencing reads were aligned to reference and variants were called using Torrent Suite software v5.8. Results: In total, 154 of 182 previously mutation negative HTNs were positive for TSHR or GNAS mutations, resulting in an 85% prevalence of TSHR and GNAS mutations in HTNs, 79% and 6%, respectively. In a subset of 25 HTNs with multiple samples per nodule, and analyzed by tNGS at high sequencing depth, TSHR mutations were detected in 23 (92%) HTNs and 1 GNAS mutation was detected in 1 (4%) HTN, 96% mutation positive HTNs in this subset. Conclusions: Owing to the higher sensitivity of tNGS as compared with denaturing gradient gel electrophoresis and HRM-PCR, TSHR or GNAS mutations could be detected in 85% of HTNs. The detection of TSHR and GNAS mutations occurred in 96% of HTNs in a sample set with multiple samples per nodule analyzed by tNGS. Taken together with the fact that no other driver mutations could be identified by whole exome sequencing, our study strongly supports the hypothesis that TSHR and GNAS mutations are the main somatic mutations leading to HTNs.

Incidence of Breakthrough Reaction in Patients with Prior Acute Allergic-Like Reactions to Iodinated Contrast Media according to the Administration Route

Objective

This study assessed the risk of acute allergic-like reactions (AARs) after extravascular administration of iodinated contrast media (ICM) in at-risk patients compared with that after intravascular ICM administration.

Materials and Methods

From July 2012 to January 2016, 264 patients with a history of moderate or severe reactions to ICM, with re-exposure to ICM intravascularly or extravascularly were included. The incidence of recurrent AARs after ICM re-exposure were assessed according to the administration routes by reviewing electronic medical records and comparison between the two routes.

Results

Among 264 patients, 244 patients had been subsequently exposed to ICM intravascularly, 7 patients via an extravascular route and 13 patients with dual re-exposure. Of 257 patients with intravascular ICM re-exposure, 87 (33.9%) had mild to severe recurrent AARs and 143 (19.5%) cases of recurrent AARs occurred among 733 cases of intravascular ICM re-exposure on a case-by-case basis. However, there was no case of recurrent ARR after extravascular administration of ICM in 20 patients (45 cases) with ICM administrated extravascularly.

Conclusion

For high-risk patients with a history of moderate or severe reactions to ICM, AARs upon extravascular administration of ICM are significantly infrequent compared with intravascular ICM administration.

Stratified premedication strategy for the prevention of contrast media hypersensitivity in high-risk patients

BACKGROUND

Although the severity of hypersensitivity reactions to iodinated contrast media varies, it is well correlated with the severity of recurrent reactions; however, prophylaxis protocols are not severity-stratified.

OBJECTIVE

To assess the outcomes of tailored prophylaxis according to the severity of hypersensitivity reactions to iodinated contrast media.

METHODS

Our premedication protocols were stratified based on the severity of previous reactions: (1) 4 mg of chlorpheniramine for mild reactions, (2) adding 40 mg of methylprednisolone for moderate reactions, and (3) adding multiple doses of 40 mg of methylprednisolone for severe index reactions. Cases of reexposure in patients with a history of hypersensitivity reactions were routinely monitored and mandatorily recorded.

RESULTS

Among a total of 850 patients who underwent enhanced computed tomography after severity-tailored prophylaxis, breakthrough reactions occurred in 17.1%, but most breakthrough reactions (89.0%) were mild and did not require medical treatment. Additional corticosteroid use did not reduce the breakthrough reaction rate in cases with a mild index reaction (16.8% vs 17.2%, P = .70). However, underpremedication with a single dose of corticosteroid revealed significantly higher rates of breakthrough reaction than did double doses of corticosteroid in cases with a severe index reaction (55.6% vs 17.4%, P = .02). Changing the iodinated contrast media resulted in an additional reduction of the breakthrough reaction rate overall (14.9% vs 32.1%, P = .001).

CONCLUSION

In a total severity-based stratified prophylaxis regimens and changing iodinated contrast media can be considered in patients with a history of previous hypersensitivity reaction to iodinated contrast media to reduce the risk of breakthrough reactions.

Somatic mutations in 33 benign and malignant hot thyroid nodules in children and adolescents

Hot thyroid nodules (HTNs) in children are rare. Their reported malignancy rate is higher than in adults. However molecular data are rare. We present clinical and molecular data for 33 consecutive (29 benign and 4 malignant) HTNs. 17/29 Benign HTNs (59%) harbored somatic TSHR mutations. The most commonly observed mutation was M453T (in 8/29 samples). T632I and D633Y mutations were each detected twice. All other TSHR mutations were each found in one sample, including the new A538T mutation. One NRAS mutation was detected in a benign HTN with a M453T mutation. A PAX8/PPARG rearrangement was found in one malignant HTN. A T632I mutation was detected in one hot papillary thyroid carcinoma. The percentage of TSHR mutation positive HTNs in children and adolescents is within the range observed in adults. Contrary to adults, the M453T mutation is the predominant TSHR mutation in HTNs of children and adolescents. The increased malignancy rate of HTNs of children does not appear to be associated with RAS, BRAF, PAX8/PPARG and RET/PTC mutations.

Lack of association between autonomously functioning thyroid nodules and germline polymorphisms of the thyrotropin receptor and Gαs genes in a mild to moderate iodine-deficient Caucasian population

BACKGROUND

Mutations of the thyrotropin receptor (TSHR) and/or Gαs gene have been found in a number of, but not all, autonomously functioning thyroid nodules (AFTNs). Recently, in a 15-year-old girl with a hyperfunctioning papillary thyroid carcinoma, we found two somatic and germline single nucleotide polymorphisms (SNPs): a SNP of the TSHR gene (exon 7, codon 187) and a SNP of Gαs gene (exon 8, codon 185). The same silent SNP of the TSHR gene had been reported in patients with AFTN or familial non-autoimmune hyperthyroidism. No further data about the prevalence of the two SNPs in AFTNs as well as in the general population are available in the literature.

AIM

To clarify the possible role of these SNPs in predisposing to AFTN.

METHODS

Germline DNA was extracted from blood leukocytes of 115 patients with AFTNs (43 males and 72 females, aged 31-85 years, mean ± SD = 64 ± 13) and 100 sex-matched healthy individuals from the same geographic area, which is marginally iodine deficient. The genotype distribution of the two SNPs was investigated by restriction fragment length polymorphism-polymerase chain reaction.

RESULTS

The prevalence of the two SNPs in our study population was low and not different to that found in healthy individuals: 8 % of patients vs. 9 % of controls were heterozygous for the TSHR SNP and 4 % patients vs. 6 % controls were heterozygous for the Gαs SNP. One patient harbored both SNPs.

CONCLUSIONS

These results suggest that these two SNPs do not confer susceptibility for the development of AFTN.

Follicular variant of papillary thyroid carcinoma presenting as toxic nodule in an adolescent: coexistent polymorphism of the TSHR and Gsα genes

BACKGROUND

Autonomously functioning, "hot", thyroid nodules are not common in children and adolescents. Such nodules are not considered alarming because they are assumed to be benign adenomas. Herein, we present a 15-year-old girl with a papillary thyroid carcinoma of 3.5 cm in diameter, which was functionally autonomous and scintigraphically hot.

PATIENT FINDINGS

The patient, initially referred to our Endocrine Unit because of a thyroid nodule, returned 6 months later for symptoms of hyperthyroidism. Hyperthyroidism was confirmed biochemically. Radioactive iodine ((131)I) thyroid scintigraphy was consistent with an autonomous thyroid nodule. As per guidelines, the patient underwent surgery and a pathological examination revealed papillary carcinoma, follicular variant. The excised nodule was examined for activating mutations of the thyrotropin receptor (TSHR), Gsα (GNAS1), H-RAS, N-RAS, K-RAS, and BRAF genes by direct sequencing. No mutations were found. Nevertheless, two combined nonfunctioning mutations were detected: a single-nucleotide polymorphism (SNP) of the TSHR gene, in exon 7, at codon 187 (AAT→AAC, both encoding asparagine), and a SNP within exon 8 of the Gsα gene at codon 185 (ATC→ATT, both encoding isoleucine). Both SNPs were also identified in the germline DNA of the patient. The same SNPs were sought in the parents and brother of our patient. Her father was heterozygous for the TSHR SNP, her mother heterozygous for the Gsα SNP, and her brother was wild type.

CONCLUSIONS

This case demonstrates that the presence of hyperfunctioning thyroid nodule(s) does not rule out cancer and warrants careful evaluation, especially in childhood and adolescence to overlook malignancy.