Extra-nuclear TERT counteracts oxidative stress and promotes progression in papillary thyroid carcinoma.

The reactivation of TERT is associated with poor outcome in papillary thyroid cancer (PTC). Extra-telomeric functions of TERT were reported, with a protective role against oxidative stress (OS). The aim of the present study was to explore the extra-nuclear TERT localization in PTC and its role in cancer progression. TERT nuclear export under OS were analyzed in K1 PTC cell line. We investigated the role of different TERT localizations using specific TERT constructs that limit its localization to the nucleus or to the mitochondria. The effect of SRC kinase inhibitor PP2, which reduces TERT nuclear export, was investigated as well. Moreover, TERT localization was analyzed in 39 PTC tissues and correlated with the genetic profile and the level of OS, DNA damage and apoptosis in the tumors and with the clinical characteristics of the patients. We demonstrated that TERT is exported from the nucleus in response to OS induced either from H2O2 or the BRAF inhibitor PLX4720. We proved that extra-nuclear TERT reduces mitochondrial OS and induces mitochondrial fragmentation. Moreover, limiting mitochondrial TERT localization reduced proliferation, migration, AKT phosphorylation and glycolysis and increased DNA damage and p21 expression. Finally, in PTC tissues the fraction of mitochondrial/nuclear TERT resulted inversely correlated with OS and p21 expression and associated with tumor persistence. In conclusion, our data indicate that extra-nuclear TERT is involved in reducing the effect of excessive OS, thus promoting cancer cell survival. Extra-nuclear TERT may thus represent a marker of cancer progression and a possible therapeutic target in PTC.

Radiofrequency ablation is an effective treatment for Bethesda III thyroid nodules without genetic alterations.

Background: Radiofrequency ablation (RFA) is effective in the treatment of thyroid nodules, leading to a 50-90% reduction with respect to baseline. Current guidelines indicate the need for a benign cytology prior to RFA, though, on the other side, this procedure is also successfully used for the treatment of papillary microcarcinomas. No specific indications are available for nodules with an indeterminate cytology (Bethesda III/IV). Aim: To evaluate the efficacy of RFA in Bethesda III nodules without genetic alterations as verified by means of a custom panel. Methods: We have treated 33 patients (mean delivered energy 1069 ± 1201 J/mL of basal volume) with Bethesda III cytology, EU-TIRADS 3-4, and negative genetic panel. The mean basal nodular volume was 17.3 ± 10.7 mL. Results: Considering the whole series, the mean volume reduction rate (VRR) was 36.8 ± 16.5% at 1 month, 59.9 ± 15.5% at 6 months, and 62 ± 15.7% at 1-year follow-up. The sub-analysis done in patients with 1 and 2 years follow-up data available (n = 20 and n = 5, respectively) confirmed a progressive nodular volume decrease. At all-time points, the rate of reduction was statistically significant (P < 0.0001), without significant correlation between the VRR and the basal volume. Neither cytological changes nor complications were observed after the procedure. Conclusion: RFA is effective in Bethesda III, oncogene-negative nodules, with reduction rates similar to those obtained in confirmed benign lesions. This procedure represents a good alternative to surgery or active surveillance in this particular class of nodules, regardless of their initial volume. A longer follow-up will allow to evaluate further reduction or possible regrowth.

Canagliflozin reduces thyroid cancer cells migration in vitro by inhibiting CXCL8 and CCL2: An additional anti-tumor effect of the drug.

PURPOSE: Canagliflozin exert anti-cancer effects in several types of cancer including thyroid cancer (TC). However, whether it could modulate chemokines secreted in TC microenvironment is still unknown. The aim of the present study is to evaluate whether Canagliflozin could inhibit pro-tumorigenic chemokines CXCL8 and CCL2 and/or the TC cell migration induced by them. EXPERIMENTAL DESIGN: TC cell lines, TPC-1 and 8505C, HUVEC and normal thyroid cells NHT were treated with increasing concentrations of Canagliflozin. Viability was assessed by WST-1 and colony formation/proliferation by cristal violet. Chemokines were measured in cell supernatants by ELISA. mRNAs were evaluated by RT-PCR. TC migration (trans-well) and HUVEC proliferation (cristal violet) were assessed by treating cells with Canagliflozin alone or in combination with CXCL8 or CCL2. RESULTS: Canagliflozin reduced TC, HUVEC and NHT cells viability. The ability to form colonies of TC and the HUVEC proliferation (basal and CXCL8 or CCL2-induced) was also inhibited. mRNA and the secretion of CXCL8 was reduced in all cell types. The secretion of CCL2 was reduced by Canagliflozin in all cell types whereas its mRNA levels were reduced only in TPC-1. IL-6 was reduced in all cell types, while CXCL10 increased. More interestingly the CXCL8 and CCL2-induced TC cell migration as well as HUVEC proliferation was inhibited by Canagliflozin in both cell types. CONCLUSION: Canagliflozin exerts anti-cancer effects not only by reducing TC viability or colonies formation, but also by modulating two pro-tumorigenic chemokines resulting in reduced TC cells migration. These results expand the spectrum of canagliflozin-promoted anti-cancer effects.

Oxidative Stress Correlates with More Aggressive Features in Thyroid Cancer.

Oxidative stress (OS) can have an impact in the pathogenesis and in the progression of thyroid cancer. We investigated the levels of reactive oxygen species (ROS) in 50 malignant and benign thyroid lesions and 41 normal tissues, and correlated them with the thyroid differentiation score-TDS and the clinico-pathologic features. NOX4 expression, GPx activity and the genetic pattern of tumors were evaluated. In malignant and benign lesions, ROS generation and NOX4 protein expression were higher than in normal tissues. Follicular (FTCs) and anaplastic/poorly differentiated cancers had increased OS relative to papillary tumors (PTCs). Moreover, OS in FTCs was higher than in follicular adenomas. Mutated PTCs showed increased OS compared with non-mutated PTCs. In malignant tumors, OS was inversely correlated with TDS, and directly correlated with tumor stage and ATA risk. GPx activity was increased in tumors compared with normal tissues, and inversely correlated to OS. In conclusion, our data indicate that thyroid tumors are exposed to higher OS compared with normal tissues, while showing a compensative increased GPx activity. OS correlates with tumor aggressiveness and mutations in the MEK-ERK pathway in PTC. The inverse correlation between OS and TDS suggests that ROS may repress genes involved in thyroid differentiation.

Thyroid cancer harboring PTEN and TP53 mutations: A peculiar molecular and clinical case report.

To date, the molecular mechanisms that underline aggressiveness and resistance to tyrosine kinase inhibitors in some thyroid carcinomas (TCs) are not known yet. We report the case of a young patient with a metastatic poorly differentiated (PDTC) and follicular thyroid carcinoma (FTC) refractory to conventional therapies and to Sorafenib. The patient, despite an initial partial response, died of progressive disease 21 months after diagnosis. The genetic analysis performed on the primary tumor and on lymph nodes and distant metastases allowed to identify a frameshift mutation (p.P248Tfs*5) in the PTEN gene, never described in TC. This mutation was present in the primary tumor and, with a lower allelic frequency, in metastases diagnosed after treatment with Sorafenib. Mutations in TP53 (p.C135Y and c.920-2A>G previously detected in anaplastic carcinomas and p.M133R never found in TC) were also detected in the primary tissue together with a mono-allelic expression of the p.C135Y mutant at RNA level. At metastatic sites level, we found only the TP53 splicing mutation c.920-2A>G. The presence of defects in mismatch repair (MMR) proteins and genomic instability was also evaluated. The primary tumor showed a partial expression of MMR proteins together with a strong genomic instability. In conclusion, we demonstrated that the rare combination of somatic PTEN and TP53 mutations in a patient with a metastatic FTC, together with the presence of tumor heterogeneity and genomic instability, might be associated with a high tumor aggressiveness and resistance to treatments.

FAM83B is involved in thyroid cancer cell differentiation and migration.

FAM83B has been recently identified as an oncogene, but its role in thyroid cancers (TC) is still unclear. We examined the expression of FAM83B and its possible involvement in cell migration and differentiation, in neoplastic/normal thyroid tissues and in TC human cell lines. FAM83B expression in TC varies according to the tumor histotype, being significantly downregulated in more aggressive and metastatic tissues. FAM83B levels in cell lines recapitulate patients' samples variations, and its total and cytoplasmic levels decrease upon the induction of migration, together with an increase in its nuclear localization. Similar variations were detected in the primary tumor and in the metastatic tissues from a follicular TC. FAM83B knock down experiments confirmed its role in thyroid differentiation and cell migration, as demonstrated by the reduction of markers of thyroid differentiation and the increase of the mesenchymal marker vimentin. Moreover, the silencing of FAM83B significantly increased cells migration abilities, while not affecting the oncogenic RAS/MAPK/PI3K pathways. Our data indicate for the first time a role for FAM83B in TC cell differentiation and migration. Its expression is reduced in dedifferentiated tumors and its nuclear re-localization could favour distant migration, suggesting that FAM83B should be considered a possible diagnostic and prognostic biomarker.

Combined Mutational and Clonality Analyses Support the Existence of Intra-Tumor Heterogeneity in Papillary Thyroid Cancer.

Despite its potential clinical impact, intra-tumor genetic heterogeneity (ITH) has been scantly investigated in papillary thyroid cancer (PTC). We studied ITH in PTC by combining, for the first time, data derived from the evaluation of the normalized allelic frequencies (NAF) of the mutation/s, using a customized MassARRAY panel, and those obtained by the HUMARA clonality assay. Among tumors with a single mutation, 80% of cases with NAF 50 ± 5% were clonal, consistent with the presence of a single mutated clone, while 20% of cases showed a polyclonal pattern, suggesting the presence of the same mutation in two or more clones. Differently, all cases with NAF < 45% were polyclonal. Among tumors with double mutation, cases with both mutations showing NAF 50 ± 5% were monoclonal, consistent with the presence of a single clone harboring both mutations. On the other hand, all cases with double mutation at NAF < 45% were polyclonal, indicating the presence of two clones with different mutations. Finally, no significant differences in the clinico-pathological characteristics were found between monoclonal and polyclonal tumors. In conclusion, the present study adds insights into the concept of ITH in PTC, which warrants attention because the occurrence of this phenomenon is likely to affect the response to targeted drugs.

New genetics in congenital hypothyroidism.

INTRODUCTION: Congenital hypothyroidism (CH) is the most frequent neonatal endocrine disorder and one of the most common preventable forms of mental retardation worldwide. CH is due to thyroid development or thyroid function defects (primary) or may be of hypothalamic-pituitary origin (central). Primary CH is caused essentially by abnormal thyroid gland morphogenesis (thyroid dysgenesis, TD) or defective thyroid hormone synthesis (dyshormonogenesis, DH). TD accounts for about 65% of CH, however a genetic cause is identified in less than 5% of patients. PURPOSE: The pathogenesis of CH is largely unknown and may include the contribution of individual and environmental factors. During the last years, detailed phenotypic description of patients, next-generation sequence technologies and use of animal models allowed the discovery of novel candidate genes in thyroid development, function and pathways. RESULTS AND CONCLUSION: We provide an overview of recent genetic causes of primary and central CH. In addition, mode of inheritance and the oligogenic model of CH are discussed.

The thyroid risk score (TRS) for nodules with indeterminate cytology.

Cytology is the gold standard method for the differential diagnosis of thyroid nodules, though 25-30% of them are classified as indeterminate. We aimed to set up a 'thyroid risk score' (TRS) to increase the diagnostic accuracy in these cases. We prospectively tested 135 indeterminate thyroid nodules. The pre-surgical TRS derived from the sum of the scores assigned at cytology, EU-TIRADS classification, nodule measurement, and molecular characterization, which was done by our PTC-MA assay, a customized array able to cost-effectively evaluate 24 different genetic alterations including point mutations and gene fusions. The risk of malignancy (ROM) increased paralleling the score: in the category >4 and ≤ 6 (low suspicion), >6 ≤ 8 (intermediate suspicion), and >8 (high suspicion); ROM was 10, 47 and 100%, respectively. ROC curves selected the score >6.5 as the best threshold to differentiate between malignant and benign nodules (P < 0.001). The TRS > 6.5 had a better performance than the single parameters evaluated separately, with an accuracy of 77 and 82% upon inclusion of noninvasive follicular thyroid neoplasm with papillary-like nuclear features among malignant or benign cases, respectively. In conclusion, for the first time, we generated a score combining a cost-effective molecular assay with already validated tools, harboring different specificities and sensitivities, for the differential diagnosis of indeterminate nodules. The combination of different parameters reduced the number of false negatives inherent to each classification system. The TRS > 6.5 was highly suggestive for malignancy and retained a high accuracy in the identification of patients to be submitted to surgery.

The clonal origin of multifocal papillary thyroid cancer: intrathyroidal spread or independent tumors?

Multifocality is a common finding in papillary thyroid cancer but the molecular pathogenesis, prognosis and management of multifocal papillary thyroid cancer are debated. The clonal origin of multifocal papillary thyroid cancer represents a controversial aspect, as two opposite viewpoints have been proposed: independent origin or intraglandular spread. Different approaches have been used for inferring the clonality of multifocal papillary thyroid cancer, including X-chromosome inactivation, mutational analysis, determination of loss of heterozygosity and, more recently, next-generation sequencing. Next-generation sequencing, able to provide information on genetic heterogeneity and phylogenetic evolution in multifocal tumors, represents the most reliable approach. While most evidences indicated an independent origin of multifocal papillary thyroid cancer, a minority of studies suggested that multifocal papillary thyroid tumors might be monoclonally derived. This discrepancy may reflect technical limitations; nevertheless, studies based on next-generation sequencing indicated that both independent and clonal origins are possible. The co-existence of multiple tumors implies a high degree of genetic heterogeneity, which may influence the best and targeted therapeutic strategy. On the other hand, intrathyroidal dissemination may indicate metastatic potential of the dominant tumor, thereby prompting more aggressive treatments. In conclusion, data available in the literature indicated that multifocal papillary thyroid cancer may derived from both intraglandular spread and independent tumor foci. The understanding of the clonal origin of multifocal papillary thyroid tumors might represent an important issue in patient treatment.

The molecular and gene/miRNA expression profiles of radioiodine resistant papillary thyroid cancer.

BACKGROUND: Papillary thyroid cancer (PTC) is the most frequent endocrine tumor. Radioiodine (RAI) treatment is highly effective in these tumors, but up to 60% of metastatic cases become RAI-refractory. Scanty data are available on either the molecular pattern of radioiodine refractory papillary thyroid cancers (PTC) or the mechanisms responsible for RAI resistance. METHODS: We analyzed the molecular profile and gene/miRNA expression in primary PTCs, synchronous and RAI-refractory lymph node metastases (LNMs) in correlation to RAI avidity or refractoriness. We classified patients as RAI+/D+ (RAI uptake/disease persistence), RAI-/D+ (absent RAI uptake/disease persistence), and RAI+/D- (RAI uptake/disease remission), and analyzed the molecular and gene/miRNA profiles, and the expression of thyroid differentiation (TD) related genes. RESULTS: A different molecular profile according to the RAI class was observed: BRAFV600E cases were more frequent in RAI-/D+ (P = 0.032), and fusion genes in RAI+/D+ cases. RAI+/D- patients were less frequently pTERT mutations positive, and more frequently wild type for the tested mutations/fusions. Expression profiles clearly distinguished PTC from normal thyroid. On the other hand, in refractory cases (RAI+/D+ and RAI-/D+) no distinctive PTC expression patterns were associated with either tissue type, or RAI uptake, but with the driving lesion and BRAF-/RAS-like subtype. Primary tumors and RAI-refractory LNMs with BRAFV600E mutation display transcriptome similarity suggesting that RAI minimally affects the expression profiles of RAI-refractory metastases. Molecular profiles associated with the expression of TPO, SLC26A4 and TD genes, that were found more downregulated in BRAFV600E than in gene fusions tumors. CONCLUSIONS: The present data indicate a different molecular profile in RAI-avid and RAI-refractory metastatic PTCs. Moreover, BRAFV600E tumors displayed reduced differentiation and intrinsic RAI refractoriness, while PTCs with fusion oncogenes are RAI-avid but persistent, suggesting different oncogene-driven mechanisms leading to RAI refractoriness.

Update on Fundamental Mechanisms of Thyroid Cancer.

The incidence of thyroid cancer (TC) has increased worldwide over the past four decades. TC is divided into three main histological types: differentiated (papillary and follicular TC), undifferentiated (poorly differentiated and anaplastic TC), and medullary TC, arising from TC cells. This review discusses the molecular mechanisms associated to the pathogenesis of different types of TC and their clinical relevance. In the last years, progresses in the genetic characterization of TC have provided molecular markers for diagnosis, risk stratification, and treatment targets. Recently, papillary TC, the most frequent form of TC, has been reclassified into two molecular subtypes, named BRAF-like and RAS-like, associated to a different range of cancer risks. Similarly, the genetic characterization of follicular TC has been proposed to complement the new histopathological classification in order to estimate the prognosis. New analyses characterized a comprehensive molecular profile of medullary TC, raising the role of RET mutations. More recent evidences suggested that immune microenvironment associated to TC may play a critical role in tumor invasion, with potential immunotherapeutic implications in advanced and metastatic TC. Several types of ancillary approaches have been developed to improve the diagnostic value of fine needle aspiration biopsies in indeterminate thyroid nodules. Finally, liquid biopsy, as a non-invasive diagnostic tool for body fluid genotyping, brings a new prospective of disease and therapy monitoring. Despite all these novelties, much work remains to be done to fully understand the pathogenesis and biological behaviors of the different types of TC and to transfer this knowledge in clinical practice.

Intratumoral Genetic Heterogeneity in Papillary Thyroid Cancer: Occurrence and Clinical Significance.

Intratumoral heterogeneity (ITH) refers to a subclonal genetic diversity observed within a tumor. ITH is the consequence of genetic instability and accumulation of genetic alterations, two mechanisms involved in the progression from an early tumor stage to a more aggressive cancer. While this process is widely accepted, the ITH of early stage papillary thyroid carcinoma (PTC) is debated. By different genetic analysis, several authors reported the frequent occurrence of PTCs composed of both tumor cells with and without RET/PTC or BRAFV600E genetic alterations. While these data, and the report of discrepancies in the genetic pattern between metastases and the primary tumor, demonstrate the existence of ITH in PTC, its extension and biological significance is debated. The ITH takes on a great significance when involves oncogenes, such as RET rearrangements and BRAFV600E as it calls into question their role of driver genes. ITH is also predicted to play a major clinical role as it could have a significant impact on prognosis and on the response to targeted therapy. In this review, we analyzed several data indicating that ITH is not a marginal event, occurring in PTC at any step of development, and suggesting the existence of unknown genetic or epigenetic alterations that still need to be identified.

DUOX2/DUOXA2 Mutations Frequently Cause Congenital Hypothyroidism that Evades Detection on Newborn Screening in the United Kingdom.

Background: The etiology, course, and most appropriate management of borderline congenital hypothyroidism (CH) are poorly defined, such that the optimal threshold for diagnosis with bloodspot screening thyrotropin (bsTSH) measurement remains controversial. Dual oxidase 2 (DUOX2) mutations may initially cause borderline elevation of bsTSH, which later evolves into significant hypothyroidism on venous blood measurement. It was hypothesized that mutations in both DUOX2 and its accessory protein DUOXA2 may occur frequently, even in patients with borderline bsTSH elevation, such that higher diagnostic thresholds in bsTSH screening may fail to detect such cases, with consequent risk of undiagnosed neonatal hypothyroidism of sufficient magnitude to require thyroxine therapy. This study aimed to investigate the frequency and characteristics of DUOX2 and DUOXA2 mutations in a borderline CH cohort. Methods: A cross-sectional study of patients with borderline CH was undertaken at Great Ormond Street Hospital, a tertiary British pediatric center. DUOX2 was sequenced in 52 patients with a bsTSH of 6-19.9 mIU/L, venous TSH of >25 mIU/L, and eutopic thyroid gland in situ. DUOXA2 was sequenced in DUOX2 mutation-negative cases, and novel DUOXA2 mutations were functionally characterized. Results: A total of 26 (50%) patients harbored likely pathogenic mutations in DUOX2 (n = 20; 38%) or DUOXA2 (n = 6; 12%), including novel gene variants (DUOX2, n = 3; DUOXA2, n = 7). Two recurrent DUOX2 mutations (p.Q570L, p.F966Sfs*29) occurred frequently in population databases (MAF ≥0.01). Despite bsTSH being <10 mIU/L in 46% of DUOX2 and DUOXA2 mutation-positive cases, venous free thyroxine levels in these patients were in the moderate CH range (M = 9.3 pmol/L, range <3.9-15.8 pmol/L), Conclusions: Targeted DUOX2 and DUOXA2 sequencing in a borderline CH cohort has a high diagnostic yield. These findings might argue for a lowering of bsTSH thresholds, but follow-up studies are required to assess whether cases with borderline bsTSH harboring DUOX2/DUOXA2 mutations will benefit from an early diagnosis and subsequent levothyroxine treatment.

The BRAF-inhibitor PLX4720 inhibits CXCL8 secretion in BRAFV600E mutated and normal thyroid cells: a further anti-cancer effect of BRAF-inhibitors.

CXCL8 is a chemokine secreted by normal and thyroid cancer cells with proven tumor-promoting effects. The presence of BRAFV600E mutation is associated with a more aggressive clinical behavior and increased ability to secrete CXCL8 by papillary-thyroid-cancer cells. Aim of this study was to test the effect of the BRAF-inhibitor (PLX4720) on the basal and TNF-α-induced CXCL8 secretions in BRAFV600E mutated (BCPAP, 8305C, 8505C), in RET/PTC rearranged (TPC-1) thyroid-cancer-cell-lines and in normal-human-thyrocytes (NHT). Cells were incubated with increasing concentrations of PLX4720 alone or in combination with TNF-α for 24-hours. CXCL8 concentrations were measured in the cell supernatants. PLX4720 dose-dependently inhibited the basal and the TNF-α-induced CXCL8 secretions in BCPAP (F: 14.3, p < 0.0001 for basal and F: 12.29 p < 0.0001 for TNF-α), 8305C (F: 407.9 p < 0.0001 for basal and F: 5.76 p < 0.0001 for TNF-α) and 8505C (F:55.24 p < 0.0001 for basal and F: 42.85 p < 0.0001 for TNF-α). No effect was found in TPC-1 (F: 1.8, p = 0.134 for basal; F: 1.6, p = 0.178 for TNF-α). In NHT an inhibitory effect was found only at the highest concentration of PLX4720 (F: 13.13 p < 0.001 for basal and F: 2.5 p < 0.01 for TNF-α). Cell migration assays showed that PLX4720 reduced both basal and CXCL8-induced cell migration in BCPAP, 8305C, 8505C and NHT but not in TPC-1 cells. These results constitutes the first demonstration that PLX4720 is able to inhibit the secretion of CXCL8 in BRAFV600E mutated thyroid cancer cells indicating that, at least some, of the anti-tumor activities of PLX4720 could be exerted through a lowering of CXCL8 in the thyroid-cancer-microenvironment.

Impact of Mutation Density and Heterogeneity on Papillary Thyroid Cancer Clinical Features and Remission Probability.

BACKGROUND: The need to integrate the classification of cancer with information on the genetic pattern has emerged in recent years for several tumors. METHODS: The genomic background of a large series of 208 papillary thyroid cancers (PTC) followed at a single center was analyzed by a custom MassARRAY genotyping platform, which allows the simultaneous detection of 19 common genetic alterations, including point mutations and fusions. RESULTS: Of the PTCs investigated, 71% were found to have pathognomonic genetic findings, with BRAFV600E and TERT promoter mutations being the most frequent monoallelic alterations (42% and 23.5%, respectively), followed by RET/PTC fusions. In 19.2% of cases, two or more point mutations were found, and the co-occurrence of a fusion with one or more point mutation(s) was also observed. Coexisting BRAFV600E and TERT promoter mutations were detected in a subgroup of aggressive PTCs (12%). A correlation between several aggressive features and mutation density was found, regardless of the type of association (i.e., only point mutations, or point mutations and fusions). Importantly, Kaplan-Meier curves demonstrated that mutation density significantly correlated with a higher risk of persistent disease. In most cases, the evaluation of the allelic frequencies normalized for the cancer cell content indicated the presence of the monoallelic mutation in virtually all tumor cells. A minority of cases was found to harbor low allelic frequencies, consistent with the presence of the mutations in a small subset of cancer cells, thus indicating tumor heterogeneity. Consistently, the presence of coexisting genetic alterations with different allelic frequencies in some tumors suggests that PTC can be formed by clones/subclones with different mutational profiles. CONCLUSIONS: A large mono-institutional series of PTCs was fully genotyped by means of a cost- and time-effective customized panel, revealing a strong impact of mutation density and genetic heterogeneity on the clinical features and on disease outcomes, indicating that an accurate risk stratification of thyroid cancer cannot rely on the analysis of a single genetic event. Finally, the heterogeneity found in some tumors warrants attention, since the occurrence of this phenomenon is likely to affect response to targeted therapies.

Genetics and management of congenital hypothyroidism.

Several evidences support a relevant genetic origin for Congenital Hypothyroidism (CH), however familial forms are uncommon. CH can be due to morphogenetic or functional defects and several genes have been originally associated either with thyroid dysgenesis or dyshormonogenesis, with a highly variable expressivity and a frequently incomplete penetrance of the genetic defects. The phenotype-driven genetic analyses rarely yielded positive results in more than 10% of cases, thus raising doubts on the genetic origin of CH. However, more recent unsupervised approaches with systematic Next Generation Sequencing (NGS) analysis revealed the existence of hypomorphic alleles of these candidate genes whose combination can explain a significant portion of CH cases. The co-segregation studies of the hypothyroid phenotype with multiple gene variants in pedigrees confirmed the potential oligogenic origin of CH, which finally represents a suitable explanation for the frequent sporadic occurrence of this disease.

Letter regarding the article: "Multiple HABP2 variants in familial papillary thyroid carcinoma: Contribution of a group of "thyroid-checked" controls" by Kern et al.

This Journal recently published a study (Kern et al., 2017) reporting the genetic analysis of the whole HABP2 gene in 11 independent kindreds with familial non medullary thyroid cancer (FNMTC). The Authors showed that a new variant (p.R122W) displayed a minor allele frequency (MAF) significantly higher in FNMTC patients than in controls (7.5 vs 0.73%, p = 0.016) and cosegregated with thyroid cancer in one kindred, thus suggesting the need for the evaluation of its possible pathogenicity in other series. We thus analyzed this new HABP2 p.R122W variant in our wide series of 32 unrelated FNMTC Italian kindreds. The variant was not found in any of the 72 affected and 12 not affected family members. In conclusion, the HABP2R122W was not found in our wide series and it is thus unlikely to be causal to FNMTC. We therefore suggest that careful replication studies should be performed when assessing the possible association between FNMTC risk and any HABP2 variant.

MassARRAY-based simultaneous detection of hotspot somatic mutations and recurrent fusion genes in papillary thyroid carcinoma: the PTC-MA assay.

PURPOSE: We exploited the MassARRAY (MA) genotyping platform to develop the "PTC-MA assay", which allows the simultaneous detection of 13 hotspot mutations, in the BRAF, KRAS, NRAS, HRAS, TERT, AKT1, PIK3CA, and EIF1AX genes, and six recurrent genetic rearrangements, involving the RET and TRK genes in papillary thyroid cancer (PTC). METHODS: The assay was developed using DNA and cDNA from 12 frozen and 11 formalin-fixed paraffin embedded samples from 23 PTC cases, together with positive and negative controls. RESULTS: The PTC-MA assay displays high sensitivity towards point mutations and gene rearrangements, detecting their presence at frequencies as low as 5%. Moreover, this technique allows quantification of the mutated alleles identified at each tested locus. CONCLUSIONS: The PTC-MA assay is a novel MA test, which is able to detect fusion genes generated by genomic rearrangements concomitantly with the analysis of hotspot point mutations, thus allowing the evaluation of key diagnostic, prognostic, and therapeutic markers of PTC in a single experiment without any informatics analysis. As the assay is sensitive, robust, easily achievable, and affordable, it is suitable for the diagnostic practice. Finally, the PTC-MA assay can be easily implemented and updated by adding novel genetic markers, according to clinical requirements.

Disorders of H2O2 generation.

After the identification of thyroid H2O2 generation system (DUOX) and of its maturation factors (DUOXA), defects in DUOX2 and/or DUOXA2 were rapidly recognized as the possible cause of congenital hypothyroidism (CH) due to thyroid dyshormonogenesis. The present Review reports data on the prevalence of DUOX2 mutations, which is variable among different series but invariably high, pointing to DUOX2 defects as one of the leading causes of dyshormonogenesis. Differently, DUOXA defects seem to be rarely involved in the pathogenesis of CH. Genotype-phenotype correlations are also reported, highlighting the great intra- and inter-familial phenotype variability which appears to be a constant feature of the defects in the H2O2 generation systems. Finally, the hypotheses to explain the phenotypic variability of the DUOX2/A2 mutations are discussed, such as the existence of other H2O2 generating systems, the age variability in thyroid hormones requirements, the differences in ethnicity, in iodine intake, and in the methodological approaches.