Classical V600E and other non-hotspot BRAF mutations in adult differentiated thyroid cancer.

BACKGROUND: BRAF is the most frequently mutated gene in differentiated thyroid cancer (DTC). Previous studies on DTC have well documented high rates of the BRAF (V600E) mutation in patients of mixed ages. Previous studies either included a mix of pediatric and adult patients or pediatric patients only. However, the prevalence of hotspot and non-hotspot BRAF mutations and its significance in pure adult DTCs is not yet well determined. In this study we determine the frequency of this classical BRAF mutation and other rare BRAF mutations in pure adult DTCs. METHODS: A total of 204 adult DTC samples (Age >18 years) were analyzed for mutations in exon 15 of the BRAF gene by performing polymerase chain reaction (PCR) amplification of tumor genomic DNAs and direct sequencing of amplicons using Sanger sequencing. Obtained results were correlated to clinical and pathological characteristics of DTCs. Statistical analyses were performed using SPSS (The Statistical Package for Social Sciences) version 20 software. RESULTS: Overall, BRAF mutations were identified in 48.5 % (99/204) of adult DTCs. Three rare non-hotspot mutations (T599I, T599dup and K601E) were detected in four tumor samples (2 %). One (K601E) of these non-hotspot mutations occurred in conventional papillary thyroid cancer (CPTC) and other three (T599I, T599dup and K601E) were found in follicular variant PTC. We found significant association between BRAF (V600E) mutation and age (P < 0.0001), extrathyroidal invasion (P = 0.017), lymph node metastasis (P = 0.038) and TNM stage III/IV (P = 0.001). CONCLUSIONS: Our study is the first to report BRAF mutations in a pure adult sample of DTCs of Saudi Arabian ethnicity. Our results show a high rate and a strong prognostic role of the classical BRAF (V600E) mutation and also suggest a common occurrence of non-hot spot mutations in adult DTC from this highly inbred population.

Divergent gender identity in three siblings with 46XX karyotype and severely virilizing congenital adrenal hyperplasia caused by a novel CYP11B1 mutation.

OBJECTIVE: To describe conflicting gender identities in three karyotypically female siblings with congenital adrenal hyperplasia (CAH) caused by a novel mutation in the CYP11B1 gene, who were assigned as males at birth and followed up to adulthood. METHODS: We present 3 siblings (16, 14 and 10 years old) who were born with severe genital virilization and raised as males. Clinical examination showed Prader IV to V external genitalia with a stretched penile length of 7 to 11 cm. Adrenocorticotrophic hormone (ACTH) stimulation test showed a stimulated 11 deoxycortisol (11DOC) level of 12,300-18,700 µg/L (normal 0-5 µg/L). Their karyotypes were 46 XX, and they had normal-sized uterus and ovaries on pelvic ultrasound. DNA was isolated from peripheral leukocytes, and polymerase chain reaction (PCR) and direct sequencing revealed a novel CYP11B1 mutation. This mutation leads to a c.53_54 T insertion (c.53_54insT) with frameshift and truncation at c.115 (codon 39) of CYP11B1. RESULTS: Psychological evaluation of the oldest sibling suggested a female gender identity, and she declared herself as female, and female sex was re-assigned after 1 year of psychosocial adjustment. Psychological assessment for the 2 younger siblings and a fourth 46XY sibling with the same condition revealed male gender identities, and they continued their lives as males without significant difficulties. CONCLUSION: Divergent gender identity was observed in three severely masculinized 46XX siblings with CAH who carried the same CYP11B1 mutation and had comparable postnatal and probably prenatal androgen exposure and environmental circumstances. These cases suggest that the basis of gender identity is more complex than chromosomal, biochemical, and genetic constitution.

Apparent Mineralocorticoid Excess Caused by a Novel Mutation in 11-ß Hydroxysteroid Dehydrogenase Type 2 Enzyme: Its Genetics and Response to Therapy.

OBJECTIVE: To present a case of apparent mineralocorticoid excess (AME) due to a novel mutation in the HSD11B2 gene and describe the patient's response to therapy. METHODS: The clinical, biochemical, and genetic features of the proband and his family are presented. For the genetic study, DNA was extracted from peripheral leucocytes. The exons and exon-intron boundaries were polymerase chain reaction (PCR)-amplified and directly sequenced. RESULTS: A 10-year-old male presented with hypertension (HTN) and weakness and was found to have hypokalemia of 2.6 mmol/L. Plasma renin was undetectable, and plasma and urinary aldosterone were low. Serum cortisol and deoxycorticosterone were normal. Daily urinary excretion of cortisol was normal, but urinary and serum cortisone levels were undetectable. The patient was treated with spiranolactone with inadequate response. A small dose of dexamethasone was added and led to excellent control of HTN and hypokalemia. Genetic studies showed a novel missense biallelic mutation changing guanine to adenine in exon 3 (c.G526A) of the HSD11B2. This mutation changes the amino acid aspartic acid to asparagine at codon 176 (p.D176N). A monoallelic form of the same mutation was found in the parents and 3 of his 4 healthy siblings but not in a healthy sister or 100 normal subjects. CONCLUSIONS: A case of AME due to a novel mutation in HSD11B2 showed the usual features of AME but exhibited an inadequate response to spironolactone. A small dose of dexamethasone resulted in an excellent response.

Analysis of ALK, IDH1, IDH2 and MMP8 somatic mutations in differentiated thyroid cancers.

Anaplastic lymphoma kinase (ALK), isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) and matrix metalloproteinase 8 (MMP8) gene mutations have been frequently reported in human cancers; however, to the best of our knowledge, they have not been specifically examined in differentiated thyroid cancers (DTCs). Therefore, the present study aimed to determine the somatic mutational frequencies of these genes in DTCs. Mutational analysis of the ALK (exons 23, 24 and 25), IDH1 (exon 4), IDH2 (exon 4), and MMP8 (all exons 1-10) was performed in 126, 271, 271 and 50 DTCs, respectively. All the indicated exons were PCR-amplified and the PCR products were directly sequenced by Sanger sequencing. The present study identified a high frequency (86%; 43/50) of MMP8 single nucleotide polymorphism (SNP) and also found some rare SNPs of this gene (S3C, T32I, L310P and K460T) in DTCs but no somatic mutation in ALK, IDH1, IDH2 and MMP8. Analyses of 414 DTCs from The Cancer Genome Atlas revealed rare ALK (1%) and MMP8 (0.24%) mutations and none in IDH1 and IDH2. Conversely, analyses of 117 aggressive thyroid cancers [84, poorly differentiated thyroid cancer (PDTC); 33, anaplastic thyroid cancer (ATC)] from the Memorial Sloan Kettering Cancer Center cohort revealed ALK mutations in 3% of ATCs and fusions in 3.6% of PDTCs. IDH1 mutation was identified in 1.25% of PDTCs but not in ATC. IDH2 mutation was identified in 3% of ATCs but not in PDTC. The present study demonstrated that these genes are less frequently mutated in DTCs, but common in ATCs and PDTCs. It suggests that these genes serve a role in a small portion of DTCs and a more important role in ATCs and PDTCs and may serve as potential therapeutic targets in these subsets.

A Unique Genotype of Pseudohypoaldosteronism Type 1b in a Highly Consanguineous Population.

CONTEXT: Pseudohypoaldosteronism (PHA) is a condition in which serum aldosterone level is normal or elevated but its action is deficient. OBJECTIVE: This study describes the molecular genetics of PHA 1b in the highly consanguineous population of 2 Arabian Gulf countries, Saudi Arabia and Oman. METHODS: This study enrolled 22 patients from 13 unrelated families (2 families with 5 patients from Oman and 11 families with 17 patients from Saudi Arabia). All of these patients had presented within the first 10 days of life with nausea and vomiting, hyponatremia, hyperkalemia, and hypotension. We isolated DNA from peripheral blood and PCR-sequenced all exons and exon-intron boundaries of SCNN1A and, if negative, SCNN1B and SCNN1G using the Dideoxy Chain termination method. RESULTS: We found a total of 8 mutations in 13 families as follows: 6 mutations in SCNN1A, 1 in SCNN1B, and 1 in SCNN1G. All of these mutations were novel except one. SCNN1A mutations were: c.1496A>G, p.Q499R (novel) in 1 patient; c.1453C>T, p.Q485X (novel) in 1 patient; c.1322_1322delA, p.N441Tfs*41 (novel) in 2 patients of 1 family; c.876 + 2 delGAGT (novel) in 3 patients of 1 family; c.203_204 delTC, p.I68Tfs*76 (a known mutation) in 8 patients of 5 families; and whole SCNN1A gene deletion (novel) in 2 patients of 2 families. In addition, a nonsense SCNN1B mutation c.1694C>A, p.S565X (novel) was found in 3 siblings from 1 Omani family, and an SCNN1G deletion mutation c.527_528 delCA, p.T176Rfs*9 (novel) in 2 siblings from another Omani family. CONCLUSION: We characterized a unique genotype of PHA 1b with several novel gene structure-disrupting mutations in SCNN1A, SCNN1B, and SCNN1G in a highly consanguineous population.

GPCR-mediated PI3K pathway mutations in pediatric and adult thyroid cancer.

Whole exome sequencing (WES) recently identified frequent mutations in the genes of GPCR-mediated PI3K pathway (LPAR4, PIK3CA, and PTEN) in a Chinese population with papillary thyroid cancers (PTCs). The study found LPAR4 mutations as novel gene mutations in adult population with differentiated thyroid cancer (DTC). Here, we determine the prevalence of somatic mutations in this pathway (LPAR4 (exon 1), PIK3CA (exons 9 and 20) and PTEN (exons 5, 6, 7 and 8) in 323 thyroid samples consisting of 17 multinodular goiters (MNG), 89 pediatric DTCs, 204 adult DTCs, and 13 aggressive thyroid cancers including 10 poorly differentiated (PDTC) and 3 anaplastic thyroid cancer (ATC) from another ethnic population. We found 3.37% and 2.45% (includes Q214H, a novel PTEN mutation) in GPCR-mediated PI3K pathway of pediatric and adult DTCs, respectively. Analyses of 507 DTCs from thyroid Cancer Genome Atlas data (TCGA) revealed a low prevalence of mutations in this pathway (1.18%). In 13 cases with PDTC and ATC, we found no mutation in genes of this pathway. By contrast, analyses of 117 aggressive thyroid cancers (PDTC and ATC) from TCGA showed 13% of mutations in this pathway. Moreover, analyses of 1080 pan-cancer cell lines and 9020 solid tumors of TCGA data revealed high rates of mutations in this pathway (cell lines, 24.8%; tumors, 24.8%). In addition, PIK3CA + PTEN (p = <0.001) and LPAR4 + PIK3CA (p = 0.003) significantly co-occurred. Our study reveals a low prevalence of GPCR-mediated PI3K pathway mutations both in pediatric and adult DTCs corroborating the TCGA data and suggests a significant role of this pathway only in a small portion of DTCs. The high prevalence of mutations in this pathway in other solid malignancies suggests an important role in their pathogenesis making it an attractive target for therapeutic intervention both in a small subset of DTCs and other solid cancers.

Absence of EIF1AX, PPM1D, and CHEK2 mutations reported in Thyroid Cancer Genome Atlas (TCGA) in a large series of thyroid cancer.

INTRODUCTION: The Thyroid Cancer Genome Atlas (TCGA) was a major project that significantly clarified the key underlying genetic aberrations in papillary thyroid cancer. It confirmed the previously known somatic mutations and gene fusions and disclosed additional genetic alterations that were previously unknown. Among the most significant novel genetic mutations were those in EIF1AX, PPM1D, and CHEK2. OBJECTIVES: We sought to determine the rates of these novel genetic alterations in a large sample of our patients to test the prevalence, reproducibility, and significance of these findings. PATIENTS AND METHODS: We studied thyroid cancer (TC) tumor tissues from 301 unselected patients using polymerase chain reaction (PCR) and direct Sanger sequencing. DNA was isolated from paraffin-embedded formalin-fixed tumor tissue. Exons and exon-intron boundaries harboring the previously reported mutations in TCGA were amplified using PCR and directly sequenced. RESULTS: We found only one of the 301 tumors (0.3%) harboring A113_splice site mutation at the intron 5/exon 6 splice site of EIF1AX gene. Apart from this single mutation, none of the 301 tumors harbored any of the previously reported mutations in any of the three genes, EIF1AX, PPM1D, and CHEK2. A number of previously reported single nucleotide polymorphisms (SNP) were found in CHEK2, PPM1D but not in EIF1AX. These include CHEK2 SNPs, rs375130261, rs200928781, rs540635787, rs142763740, and rs202104749. The PPM1D SNPs rs771831676 and rs61757742 were present in 1.49% and 0.74%, respectively. Each of these SNPs was present in a heterozygous form in 100% of the tumors. An additional analysis of these samples for the most frequently reported mutations in DTC such as BRAFV600E, TERT promoter, and RAS showed a prevalence of 38.87% (117/301), 11.96% (36/301), and 7.64% (23/301), respectively. CONCLUSIONS: Except for a rare A113_splice site mutation in EIF1AX, other recently described somatic mutations in EIF1AX, PPM1D, and CHEK2 were absent in this large series of patients with TC from a different racial group (Saudi Arabia). This might be related to the different techniques used (PCR and direct sequencing) or low density of the mutants. It might also reflect racial differences in the rate of these mutations.

Correction to: Absence of EIF1AX, PPM1D, and CHEK2 mutations reported in Thyroid Cancer Genome Atlas (TCGA) in a large series of thyroid cancer.

The original version of this article unfortunately contained a mistake in the abstract and body of the article, the acronym TCGA should refer to "The Cancer Genome Atlas" not "Thyroid Cancer Genome Atlas". This has been corrected with this erratum.

Lung Metastasis in Pediatric Thyroid Cancer: Radiological Pattern, Molecular Genetics, Response to Therapy, and Outcome.

Context: Lung metastases are common in pediatric thyroid cancer (TC). We present an analysis of a series of lung metastases in pediatric TC. Patients and Methods: Data from 20 patients (16 females, 4 males; median age, 14.5 years; range 10 to 18 years) were analyzed. The tumors included differentiated TC in 19 patients and poorly differentiated TC in 1 patient. Results: Lung metastasis presented with three distinct radiological patterns: lung uptake on diagnostic radioactive iodine whole body scan (DxWBS) only in 3 patients (15%); lung uptake on DxWBS and CT scan as micrometastases (≤1 cm) in 16 patients (80%); and lung uptake on DxWBS and CT scan as macrometastases (>1 cm) in 1 patient (5%). Iodine-131 therapies were administered to all patients (median, three; range one to eight) with a median cumulative administered activity of 317.5 mCi (range, 109 to 682 mCi). None of the patients achieved a complete response but the biochemical response was substantial. During a median follow-up period of 8.2 years (range, 0.75 to 16.3 years), 1 patient (5%) died, 1 patient (5%) had a biochemically incomplete response, 2 patients (10%) had an indeterminate response, 1 patient (5%) had progressive structural disease, and 14 patients (70%) had stable structural disease. Mutational testing of 10 of 20 tumors revealed only two PIK3CA mutations in a single tumor. Conclusions: Lung metastases are common in pediatric TC and present most frequently with bilateral radioiodine-avid micrometastases. Known single point mutations in adult TC are rare in pediatric TC. The biochemical response to iodine-131 can be substantial but resolution of structural abnormalities is rare.

Molecular genetics and phenotype/genotype correlation of 5-α reductase deficiency in a highly consanguineous population.

CONTEXT AND OBJECTIVES: 5-α reductase deficiency is a rare 46,XY disorder of sex development. We present detailed phenotypic and genotypic features of a cohort of 24 subjects from a highly consanguineous population of Saudi Arabia SUBJECTS AND METHODS: We studied the clinical presentation and hormonal profiles of 24 subjects diagnosed with 5-α reductase deficiency and performed genetic testing on DNA isolated from their peripheral blood using polymerase chain reaction and direct sequencing of the SRD5A2. RESULTS: All subjects had 46,XY karyotype and presented with atypical appearance of external genitalia ranging from clitoromegaly, micophallus with hypospadias, undescended testes to completely normally looking female genitalia. Thirteen (54%) of them had severe under virilization and were assigned female sex at birth. The other 11 subjects were raised as males. Stimulated Testosterone:Dihydrotestosterone ratio was high in all 16 subjects in whom it was measured. The genetic testing revealed 2 nonsense mutations (p.R103X and p.R227X) in 2 unrelated subjects, 3 missense mutations (p.P181L, p.A228T, p.R246Q) in 11 subjects and a splice site mutation (IVS1-2A > G) in 11 other subjects. There was significant phenotypic variability even in subjects with the same mutation and also within the same family. CONCLUSION: This is the first and largest report of the clinical and molecular genetics of 5-α reductase deficiency from the Middle East. It shows weak genotype/phenotype correlation and significant phenotypic heterogeneity. IVS1-2A > G mutation is the most common mutation and is likely to be a founder mutation in this part of the world.

Mutational analysis of rare subtypes of congenital adrenal hyperplasia in a highly inbred population.

CONTEXT: Apart from 21 Hydroxylase deficiency, other subtypes of congenital adrenal hyperplasia (CAH) are rare. We studied the clinical features and molecular genetics of a relatively large series of patients with CYP17A1, HSD3ß2 and StAR deficiencies. PATIENTS AND METHODS: We studied 21 patients including 7 patients with CYP17A1, 10 patients with HSD3ß2 and 4 patients with StAR deficiencies. For mutation detection, we isolated DNA from peripheral leucocytes, amplified genes of interest using polymerase chain reaction and directly sequenced the amplicons using Dideoxy Chain Termination method. RESULTS: Regardless of their karyotype, patients with CYP17A1 deficiency presented with normally looking external female genitalia and were raised as females. Hypertension and hypokalemia were prominent features in 4 of 7 patients. Two missense (p.R416H, p.R239Q) and 2 non-sense (p.Y329X, p.Y329X) mutations were found in these 7 cases. In 3 unrelated families with 10 affected siblings with HSD3ß2 mutations, two non-sense mutations were found (p.Q334X, p.R335X). 46XY patients with HSD3ß2 deficiency presented with ambiguous genitalia while 46XX patients presented with normal female external genitalia. Adrenal crisis was common in patients with both karyotypes. In the 4 patients with StAR deficiency, both genetic male and female patients presented with normally looking female external genitalia and adrenal crisis. One previously reported missense mutation (p.R182H) was found in 3 unrelated patients and a novel non-sense mutation (p.Q264X) in the fourth patient. CONCLUSIONS: These cases of rare subtypes of CAH illustrate the heterogeneous phenotypic and genetic features of these subtypes and add unique novel mutations to the previously known ones.

Single Point Mutations in Pediatric Differentiated Thyroid Cancer.

PURPOSE: Differentiated thyroid cancer (DTC) is rare in children. Previous studies have suggested that it has different clinicopathologic features and mutation profiles compared with adult DTC. However, those studies focused on a single or limited number of gene mutations. This study comprehensively investigated a large series of pediatric DTC for single point mutations in BRAF, HRAS, KRAS, NRAS, PIK3CA, PTEN, and TERT. It also analyzed associations between clinicopathologic features and the BRAFV600E mutation. PATIENTS AND METHODS: Eighty-nine consecutive cases seen in children and adolescents (≤18 years) during 1998-2015 were identified. Rare variants of DTC were excluded, and the study focused on 72 (91.1%) classical papillary thyroid carcinoma (PTC) and seven (8.9%) follicular variant PTC. These included 68 (86.1%) females and 11 (13.9%) males, with a median age of 15.5 years (range 8-18 years). The clinical and histopathological data were obtained from medical records. DNA was extracted from paraffin-embedded tumor tissue, and was PCR-amplified and directly sequenced. RESULTS: Mutations detected included BRAFV600E in 19/72 (26.4%) classical PTC samples, and in none of seven follicular variant PTC. Other mutations included: 1/78 (1.3%) successfully amplified tumor samples with TERT C228T; 2/79 (2.5%) NRAS 61 (c.181C>A and c.182A>G); 1/73 (1.4%) PIK3CA exon 9 (c.1589A>G and c.1598C>T in one tumor); 1/79 (1.3%) PIK3CA exon 20 (c.2951G>A); and 1/74 (1.4%) PTEN exon 5 (c.295G>A). No mutation was found in HRAS, KRAS, NRAS12, PTEN exons 6, 7, and 8, and TERT C250T. No significant association was found between BRAFV600E mutation and sex, extrathyroidal invasion, tumor multifocality, vascular invasion, lymph node or distant metastases, and persistent/recurrent disease. CONCLUSIONS: In pediatric DTC, the prevalence of the BRAFV600E mutation is significantly less common compared with adult DTC, and there is no association between this mutation and the histopathological features and outcome of PTC. PIK3CA, PTEN, NRAS 61, and TERT C228T mutations are rare.

A high rate of novel CYP11B1 mutations in Saudi Arabia.

Despite ethnic variation, 11 ß-hydroxylase deficiency (11ß-OHD) has generally been considered the second most common subtype of congenital adrenal hyperplasia (CAH). We report a high rate of novel mutations in this gene (CYP11B1) in patients from Saudi Arabia. We studied 16 patients with 11ß-OHD from 8 unrelated families. DNA was isolated from peripheral blood. The 9 exons and exon-intron boundaries of CYP11B1 were PCR-amplified and directly sequenced. The novel mutations were functionally characterized using subcloning, in vitro mutagenesis, cell transfection and 11-deoxycortisol: cortisol conversion assays. Six mutations were found in these 8 unrelated families. Three of these mutations are completely novel and two have just been recently described as novel mutations from the same population. These include a single nucleotide insertion mutation in codon 18 (c.53_54insT) leading to frameshift and truncation in 4 siblings, a novel mutation (c.1343G>C, p.R448P) in 3 unrelated families, a novel mutation (c.1394A>T, p.H465L) in 2 siblings, a novel mutation (c.617G>T, p.G206V) in 1 patient, and a recently described non-sense novel mutation (c.780G>A, p.W260X) in another patient. Out of the 6 mutations described in this report, only one mutation (p.Q356X) was reported previously. In vitro functional testing of the 3 missense and nonsense novel mutations revealed complete loss of the 11 hydroxylase activity. We conclude that 11 ß-OHD in Saudi Arabia has a unique genotype with a high rate of novel mutations. The novel p. R448P mutation is the most common mutation in this highly inbred population.

HABP2 Gene Mutations Do Not Cause Familial or Sporadic Non-Medullary Thyroid Cancer in a Highly Inbred Middle Eastern Population.

BACKGROUND: Familial non-medullary thyroid cancer (NMTC) occurs either as part of known hereditary syndromes or as a non-syndromic isolated hereditary tumor. Although the genes underlying the syndromic type of NMTC have been identified in most syndromes, no clear underlying gene has been identified in the non-syndromic NMTC. Recently, a c.1601G>A, p.G534E mutation in the HABP2 gene was reported to be the underlying genetic defect in a family with seven members affected by NMTC. The G534E variant has also been reported to occur in about 4.7% of cases of the Thyroid Cancer Genome Atlas (TCGA) database. OBJECTIVES: The aim of this study was to explore whether the recent finding of G534E genetic variant can be replicated in a large sample of NMTC, including 11 members of four unrelated families with familial NMTC and 509 cases of sporadic pediatric (63 cases) and adult NMTC (446 cases). METHODS: All exons and exon-intron boundaries of HABP2 were screened in 11 members of four families with familial non-syndromic NMTC using DNA isolated from peripheral leucocytes, polymerase chain reaction, and direct sequencing. The G534E variant was also screened for specifically in 229 cases of sporadic NMTC using DNA isolated from peripheral leucocytes and an additional 217 cases of NMTC using DNA isolated from formalin-fixed paraffin-embedded tumor tissues. As a control cohort, 190 healthy individuals without known thyroid disease were also studied for the presence of the G534E variant using DNA isolated from peripheral leucocytes. RESULTS: None of the familial NMTC carried HABP2 mutations. Of 509 sporadic NMTC, only one case (0.2%) harbored the G534E variant. Similarly, only one case (0.5%) of the control group harbored the G534E variant. CONCLUSION: In this study, HABP2 mutations were not found in familial NMTC, and the G534E variant is not the underlying genetic defect in a large sample of sporadic NMTC from the Middle East.

Uncommon TERT Promoter Mutations in Pediatric Thyroid Cancer.

PURPOSE: The aim of this study was to determine the rate and significance of TERT promoter mutations that have been recently described in adult thyroid cancer (TC) but not yet in the uncommonly occurring pediatric TC. Furthermore, the role of the BRAF(V600E) mutation in the clinical outcome of pediatric TC is unknown. METHOD: The study included 55 pediatric (median age 16 years, range 9-18 years; 46 females) and 210 adult TC patients (median age 40 years, range 20-75 years; 155 females) seen during the same time period. DNA was isolated from TC tissues and subjected to direct sequencing. Genetic-clinicopathological correlations were analyzed. RESULTS: Only one case of pediatric TC was found to harbor the C228T TERT promoter mutation (1.8%). The C250T mutation was not detected in any of the 55 pediatric TC. In contrast, there was a significantly higher rate of TERT promoter mutations in the adult patients (15.7%, 33/210) compared with the pediatric patients (p = 0.003). In addition, persistent/recurrent TC was seen in 8/12 (66.7%) pediatric patients harboring the BRAF(V600E) mutation versus 14/41 (34.1%) patients harboring the wild type BRAF (p = 0.05), and when only conventional papillary TC was examined, in 7/9 (77.8%) cases harboring BRAF(V600E) mutation versus 11/33 (33.3%) cases harboring wild type BRAF (p = 0.025). CONCLUSIONS: This is the first study on TERT promoter mutations in pediatric TC, which revealed an exceedingly low prevalence, suggesting a limited role of these mutations in pediatric TC. This study also for the first time demonstrates an association of the BRAF(V600E) mutation with TC recurrence in pediatric patients.

Absence of somatic mutations of the mTOR gene in differentiated thyroid cancer.

Thyroid cancer is the most common endocrine malignancy with increasing incidence. Mammalian target of rapamycin (mTOR) is an important downstream mediator of phosphatidylinositol 3-kinase (PI3K/Akt) signaling and regulates cell growth, apoptosis and metabolism. The mTOR gene is frequently mutated in human cancers. Although PI3K/Akt pathway and its component genes were extensively studied in thyroid cancer, it is not known whether mTOR gene is somatically mutated and play a role in differentiated thyroid cancer (DTC). To determine the status of mTOR mutations in 53 DTC, we extensively examined 19 selected exons of mTOR gene which were reported to be frequently mutated in other human cancers. Unlike in other human cancers, we did not find common somatic mutations in the mTOR gene in differentiated thyroid cancer, except for some synonymous single nucleotide polymorphisms. Our results suggest that mTOR mutation is very rare and may not play a significant role in DTC.

TERT promoter mutations in thyroid cancer: a report from a Middle Eastern population.

Telomerase reverse transcriptase (TERT) promoter mutations C228T and C250T have recently been described in follicular cell-derived thyroid cancer (TC) in patients from North America and Europe. In this study, we explored whether these findings could be replicated in patients from a different ethnic group. We screened 17 benign thyroid adenomas and 265 TC samples from patients in the Middle East for these mutations by PCR and direct sequencing using DNA isolated from paraffin-embedded tumor tissues. None of the 17 benign adenomas harbored TERT promoter mutations. Of 265 TC, 34 (12.8%) harbored TERT promoter mutations, including 10/153 (6.5%) conventional papillary TC (CPTC), 8/57 (14.0%) follicular variant PTC, 9/30 (30%) tall cell variant PTC, 1/3 (30%) Hurthle cell thyroid cancer (HTC), 1/5 (20%) follicular TC, and 5/13 (38.5%) poorly differentiated TC. C250T mutation was present in only 6/265 (2.3%) cases, while C228T mutation was present in a total of 28/265 (10.6%) cases. These two mutations were mutually exclusive. TERT promoter mutations were significantly more common in older (≥45 years) than younger patients and were associated with larger tumour size, vascular invasion, higher TNM stage (stage III and IV), BRAF(V600E) mutation and persistent/recurrent disease at 6-12 months after initial treatment and at the last follow up. These associations were stronger in non-CPTC. Thus, this study on a large cohort of TC patients from Middle East demonstrates that TERT promoter mutations are relatively common, especially in the non-CPTC, and are associated with more aggressive histopathological features, BRAF(V600E) mutation, and disease persistence/recurrence than the WT TERT.