Genetic Predisposition to Pheochromocytoma and Paraganglioma: 21 Years' Experience in the Field.

CONTEXT: Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors with high heritability, justifying systematic genetic screening for a germline variant in one of the twenty predisposing genes described to date. PURPOSE: To describe the experience of one endocrine oncogenetic laboratory over a period of 21 years (2001-2022), from the beginning of PPGL genotyping with Sanger sequencing in 2001 to the implementation of next-generation sequencing (NGS). METHOD: The activity database of an academic oncogenetic laboratory was searched to extract patients/relatives identified with a pathogenic variant/likely pathogenic variant (PV/LPV) over a period of 21 years. Clinical and genetic data were compared. RESULTS: 606 index cases with PPGL and 444 relatives were genotyped. Genotyping of index cases was performed by Sanger sequencing and gene deletion analysis in 327 cases and by NGS in 279. Germline PV/LPV spanning 10 genes was identified in 165 index cases (27.2%). Several recurrent PV/LPVs in SDHx were observed in non-related index cases, the most frequent being SDHD, c.170-1G>T (n=28). This subgroup showed great phenotypic variability both between and within families in terms of both tumor location and number. Four patients (1.1%) with PV/LPV in SDHx had 3PA (Pituitary Adenoma and pheochromocytoma/paraganglioma) syndrome. 258 relatives (58.1%) had inherited a PV/LPV in one driver gene. The rate of PV/LPV carriers who were symptomatic at first imaging evaluation was 32%, but varied between <20% in SDHB and SDHC and >50% in SDHD, VHL and MAX. CONCLUSION: Our experience confirmed previously established genotype-phenotype correlations, but also highlights atypical clinical presentations, even for the same genetic variant. These data must be taken into account for optimal patient follow-up and management.

Lessons from prospective longitudinal follow-up of a French APECED cohort.

BACKGROUND: APECED syndrome is a rare disease caused by biallelic mutations of the AIRE gene, usually presenting with the triad "hypoparathyroidism-adrenal failure-chronic mucocutaneous candidiasis (CMC)" and non-endocrine manifestations. The aim of this study was to determine the molecular profile of the AIRE gene, the prevalence of rare manifestations and to characterize immunological disturbances in a French cohort. PATIENTS AND METHODS: A national, multicenter prospective observational study to collect genetic, clinical, biological and immunological data (NCT03751683). RESULTS: 25 patients (23 families) were enrolled. Eleven distinct AIRE variants were identified, two of which were not previously reported: an intronic variant, c.653-70G > A, and a c.1066del (p.Arg356GlyfsX22) variant (exon 9). The most common was the Finnish variant c.769C > T (16 alleles), followed by the variant c.967_979del13 (15 alleles), which seemed associated with a less severe phenotype. 17/25 patients were homozygote. The median number of clinical manifestations was seven; 19/25 patients presented with the hypoparathyroidism-adrenal failure-CMC triad, 8/13 showed pulmonary involvement, 20/25 had ectodermal dystrophy, 8/25 had malabsorption, and 6/23 had asplenia. Fifteen out of 19 patients had NK cell lymphopenia with an increase in CD4+ and CD8+ T lymphocytes and an age-dependent alteration of B lymphocyte homeostasis compared with matched controls (p < 0.001), related to the severity of the disease. All tested sera (n = 18) were positive for anti-interferon-α, 15/18 for anti-interleukin-22 antibodies, and 13/18 for anti-interleukin-17F antibodies, without clear phenotypic correlation other than with CMC. CONCLUSION: This first prospective cohort showed a high AIRE genotype variability, with two new gene variants. The prevalence of potentially life-threatening non-endocrine manifestations, was higher with systematic screening. These manifestations could, along with age-dependent B-cell lymphopenia, contribute to disease severity. Systematic screening for all the manifestations of the syndrome would allow earlier diagnosis, supporting vaccination, and targeted therapeutic approaches.

A cohort study of CNS tumors in Multiple Endocrine Neoplasia Type 1.

PURPOSE: Multiple Endocrine Neoplasia Type-1 (MEN1) is thought to increase the risk of meningioma and ependymoma. Hereby, we aimed to describe the frequency, the incidence and specific clinical and histological features of CNS tumors in the MEN1 population (except pituitary tumors). EXPERIMENTAL DESIGN: The study population included patients harboring CNS tumors diagnosed with MEN1 syndrome after 1990 and followed-up in the French MEN1 national cohort. Standardized incidence rate (SIR) was calculated based on the French Gironde CNS tumors registry. Genomic analyses were performed on somatic DNA from 7 CNS tumors including meningiomas and ependymomas from MEN1 patients, then in 50 sporadic meningiomas and ependymomas. RESULTS: Twenty-nine CNS tumors were found among the 1498 symptomatic patients (2%) (incidence=47.4/100'000 person-years; SIR=4.5), including 12 meningiomas (0.8%) (incidence=16.2/100'000; SIR=2.5), 8 ependymomas (0.5%) (incidence=10.8/100'000; SIR=17.6), 5 astrocytomas (0.3%) (incidence=6.7/100'000; SIR=5.8), and 4 schwannomas (0.3%) (incidence=5.4/100'000; SIR=12.7). Meningiomas in MEN1 patients were benign, mostly meningothelial, with 11 years earlier onset compared to the sporadic population and an F/M ratio of 1/1. Spinal and cranial ependymomas were mostly classified WHO grade 2. A biallelic MEN1 inactivation was observed in 4/5 ependymomas and 1/2 meningiomas from the MEN1 patients, whereas MEN1 deletion in one allele was present in respectively 3/41 and 0/9 sporadic meningiomas and ependymomas. CONCLUSIONS: Incidence of each CNS tumor was higher in the MEN1 population than in the French general population. Meningiomas and ependymomas should be considered part of the MEN1 syndrome, but somatic molecular data are missing to conclude for astrocytomas and schwannomas.

Beyond MEN1, when to think about MEN4? Retrospective study on 5600 patients in the French population & literature review.

CONTEXT: Germline CDKN1B variants predispose patients to multiple endocrine neoplasia type 4 (MEN4), a rare MEN1-like syndrome, with <100 reported cases since its discovery in 2006. Although CDKN1B mutations are frequently suggested to explain cases of genetically-negative MEN1, the prevalence and phenotype of MEN4 patients is poorly known, and genetic counseling is unclear. OBJECTIVE: To evaluate the prevalence of MEN4 in MEN1-suspected patients and characterize the phenotype of MEN4 patients. DESIGN: Retrospective observational nationwide study. Narrative review of literature and variant class reassessment. PATIENTS: We included all adult patients with class 3/4/5 CDKN1B variants identified by the laboratories from the French TENGEN network between 2015 and 2022 through germline genetic testing for MEN1 suspicion. After class reassessment, we compared the phenotype of symptomatic patients with class 4/5 CDKN1B variants, i.e. with genetically-confirmed MEN4 diagnosis, in our series and in literature with 66 matched MEN1 patients from the UMD-MEN1 database. RESULTS: From 5600 MEN1-suspected patients analyzed, four patients with class 4/5 CDKN1B variant were found (0.07%). They presented with multiple duodenal NET, PHPT and adrenal nodule, isolated PHPT, PHPT and pNET. We listed 29 patients with CDKN1B class 4/5 variants from literature. Compared to matched MEN1 patients, MEN4 patients presented lower NET incidence and older age at PHPT diagnosis. CONCLUSION: The prevalence of MEN4 is low. PHPT and PA represent the main associated lesions, NETs are rare. Our results suggest a milder and later phenotype than in MEN1. Our observations will help to improve genetic counseling and management of MEN4 families.

Carney complex predisposes to breast cancer: prospective study of 50 women.

OBJECTIVE: Carney complex (CNC) is a rare genetic syndrome, mostly due to germline loss-of-function pathogenic variants in PRKAR1A. Carney complex includes pigmented skin lesions, cardiac myxomas, primary pigmented nodular adrenocortical dysplasia, and various breast benign tumors. DESIGN: The present study was designed to describe the characteristics of breast lesions in CNC patients and their association with other manifestations of CNC and PRKAR1A genotype. METHODS: A 3-year follow-up multicenter French prospective study of CNC patients included 50 women who were analyzed for CNC manifestations and particularly breast lesions, with breast imaging, genotyping, and hormonal settings. RESULTS: Among the 38 women with breast imaging, 14 (39%) had breast lesions, half of them bilateral. Ten women (26%) presented with benign lesions and six with breast carcinomas (16%): one had ductal carcinoma in situ at 54, and five had invasive cancer before 50 years old, whom one with contralateral breast cancer during follow-up. The occurrence of breast cancer was more frequent in women with PRKAR1A pathogenic variant odds ratio = 6.34 (1.63-17.91) than in general population of same age. The mean age at breast cancer diagnosis was 44.7 years old: 17 years younger than in the general population. Breast cancer patients had good prognosis factors. All breast carcinomas occurred in individuals with familial CNC and PRKAR1A pathogenic variants. Loss of heterozygosity at the PRKAR1A locus in the 2 invasive breast carcinomas analyzed suggested a driver role of this tumor suppressor gene. CONCLUSIONS: As CNC could predispose to breast carcinoma, an adequate screening strategy and follow-up should be discussed in affected women. CLINICAL TRIAL REGISTRATION: ClinicalTrial.gov NCT00668291.

Prevalence of Endocrine Manifestations and GIST in 108 Systematically Screened Patients With Neurofibromatosis Type 1.

Context: In patients with neurofibromatosis type 1 (NF1), guidelines suggest screening for pheochromocytoma by metanephrine measurement and abdominal imaging, which may lead to the discovery of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) and their differential diagnosis, gastrointestinal stromal tumors (GISTs). Other endocrine manifestations such as follicular thyroid carcinoma and primary hyperparathyroidism have also been reported in a few cases. Objective: This study aimed to describe prevalence and clinical presentation of these manifestations through systematic screening in a large cohort of patients. Methods: In this monocentric retrospective study, 108 patients with NF1 were included and screened for endocrine manifestations and GISTs. Clinical, laboratory, molecular profile, pathology, and morphologic (abdominal computed tomography scan and/or magnetic resonance imaging) and functional imaging were collected. Results: Twenty-four patients (22.2% of the cohort, 16 female, mean age 42.6 years) presented with pheochromocytomas that were unilateral in 65.5%, benign in 89.7%, and with a ganglioneural component in 20.7%. Three female patients (2.8% of the cohort, aged 42-63 years) presented with well-differentiated GEP-NETs, and 4 (3.7%) with GISTs. One patient had primary hyperparathyroidism, 1 patient had medullary microcarcinoma, and 16 patients had goiter, multinodular in 10 cases. There was no correlation between pheochromocytoma and other NF1 tumoral manifestations, nor correlations between pheochromocytoma and NF1 genotype, despite a familial clustering in one-third of patients. Conclusion: The pheochromocytoma prevalence in this NF1 cohort was higher (>20%) than previously described, confirming the interest of systematic screening, especially in young women. The prevalence of GEP-NETs and GISTs was about 3%, respectively. No phenotype-genotype correlation was observed.

Serum Succinate/Fumarate Ratio in Patients With Paraganglioma/Pheochromocytoma Attending an Endocrine Oncogenetic Unit.

CONTEXT: Pheochromocytomas and paragangliomas (PPGLs) with SDHx pathogenic variants (PVs) are characterized by a higher intratissular succinate/fumarate ratio (RS/F) than non-SDHx-mutated ones. Also, an increase in serum succinate levels has been reported in patients with germline SDHB or SDHD PV. OBJECTIVE: To assess whether measurement of serum succinate, fumarate levels, and RS/F might aid identification of an SDHx germline PV/likely pathogenic variant (LPV) in patients with PPGL or in asymptomatic relatives; and to guide identification of a PV/LPV among the variants of unknown significance (VUS) identified in SDHx by next-generation sequencing. METHODS: This prospective monocentric study included 93 patients attending an endocrine oncogenetic unit for genetic testing. Succinate and fumarate were measured in serum by gas chromatography coupled to mass spectrometry. The RS/F was calculated to assess SDH enzymatic function. Diagnostic performance was assessed by receiver operating characteristic analysis. RESULTS: RS/F had a higher discriminant power than succinate alone to identify an SDHx PV/LPV in patients with PPGL. However, SDHD PVs/LPVs are frequently missed. Only RS/F differed between asymptomatic SDHB/SDHD PV/LPV carriers and SDHB/SDHD-linked patients with PPGL. Finally RS/F could be helpful to easily evaluate the functional impact of VUS in SDHx. CONCLUSION: Measurement of serum RS/F in patients with PPGL and in asymptomatic relatives is a valuable initial workup tool to detect those carrying a germline PV/LPV in SDHx. Its discriminative power is equal or superior to those of succinate measured alone. SDHD PVs/LPVs are less frequently identified by these biochemical tools. Use of RS/F for SDHx VUS reclassification needs to be evaluated further.

Life expectancy and likelihood of surgery in multiple endocrine neoplasia type 1: AFCE and GTE cohort study.

BACKGROUND: The overall natural history, risk of death and surgical burden of patients with multiple endocrine neoplasia type 1 (MEN1) is not well known. METHODS: Patients with MEN1 from a nationwide cohort were included. The survival of patients with MEN1 was compared with that of the general population using simulated controls. The cumulative probabilities of MEN1-specific operations and postoperative mortality were assessed, and surgical sequences were analysed using sunburst charts and Venn diagrams. RESULTS: A total of 1386 patients with MEN1 were included. Life expectancy was significantly reduced in patients with MEN1 compared with simulated controls from the general population, with a lifetime difference of 15 years. Mutations affecting the JunD interaction domain had a significant negative impact on survival. Survival for patients with MEN1 compared with the general population improved over time. The probability of experiencing at least one specific MEN1 operation was above 95 per cent after 75 years, and most patients had surgery at least twice during their lifetime. Time to a 50 per cent risk of MEN1 surgery was 30.5 years for patients born after 1960, compared with 47.9 years for those born before 1960. Sex and mutations affecting the JunD interacting domain had no impact on time to first surgery. There was considerable heterogeneity in surgical sequences, with no specific clinical pathway. CONCLUSION: Life expectancy was significantly lower among patients with MEN1 compared with the general population, and further decreased in patients with mutations affecting the JunD interacting domain. Almost all patients underwent at least one MEN1-specific operation during their lifetime, but there was no standardized sequence of surgery.

Serum fatty acid profiling in patients with SDHx mutations: New advances on cellular metabolism in SDH deficiency.

Apart from the oncometabolite succinate, little studies have appeared on extra-mitochondrial pathways in Succinate Dehydrogenase (SDH) genetic deficiency. The role of NADH/NAD+ redox status and dependent pathways was recently emphasized. Therein, fatty acid (FA) metabolism data were collected here in 30 patients with a loss of function (LOF) variant in one SDHx gene (either with a pheochromocytoma/paraganglioma (PPGL) or asymptomatic) and in 22 wild-type SDHx controls (with PPGL or asymptomatic). Blood acylcarnitines in two patients, peroxisomal biomarkers, very long-chain saturated FA (VLCFA), and C20 to C24 n-3 polyunsaturated fatty acids (PUFA), in all patients were measured by mass spectrometry. Preliminary data showed elevated even and odd long- and very long-chain acylcarnitines in two patients with a SDHB variant. In the whole series, no abnormalities were observed in biomarkers of peroxisomal ß-oxidation (C27-bile acids, VLCFAs and phytanic/pristanic acids) in SDHx patients. However, an increased hexaene to pentaene PUFA ratio ([TetraHexaenoic Acid + DocosaHexaenoic Acid]/[n-3 DocosaPentaenoic Acid + EicosaPentaenoic Acid]) was noticed in patients with SDHC/SDHD variants vs patients with SDHA/SDHB variants or controls, suggesting a higher degree of unsaturation of PUFAs. Within the group with a SDHx variant, Eicosapentaenoate/Tetracosahexaenoate ratio, as an empiric index of shortening/elongation balance, discriminated patients with PPGL from asymptomatic ones. Present findings argue for stimulated elongation of saturated FAs, changes in shortening/elongation balance and desaturation rates of C20-C24 PUFAs in SDH-deficient patients with PPGL. Overall, oxidation of NADH sustained by these pathways might reflect or impact glycolytic NAD+ recycling and hence tumor proliferation.

Genetic biomarkers of life-threatening pheochromocytoma-induced cardiomyopathy.

The release of excessive amounts of catecholamine by pheochromocytoma-paragangliomas (PPGL) can lead to life-threatening catecholamine-induced cardiomyopathy (CIC). Single-nucleotide polymorphisms of the beta1 and alpha-2c adrenergic receptors alter myocyte receptor function and enhanced norepinephrine release. We tested the hypothesis that such genetic variations may impact the risk of developing CIC in the context of PPGL. Thirty-one patients with PPGL, including nine with a history of CIC, were analyzed for alpha-2-adrenergic receptors: ADRA2C, beta-1 and beta-2 adrenergic receptors: ADRB1 and ADRB2 genotyping. CIC was defined either by a history of heart failure or cardiogenic shock associated with dilated or Takotsubo cardiomyopathy. Subjects were genotyped for ADRA2C (rs61767072 for del322_325), ADRB1 (rs1801252 for Ser49Gly and rs1801253 for Arg389Gly) and ADRB2 (rs1042713 for Arg16Gly and rs1042714 for Gln27Glu). Single-locus analysis revealed that variant in ADRA2C (alpha 2CDel322-325) was more common among patients with CIC than among controls (allele frequency, 0.44 vs 0.05; P< 0.001). The lack of alpha 2CDel322-325 polymorphism has a negative predictive value of 95% for the onset of CIC. In a replication cohort including 26 patients with PPGL whom eight have developed a CIC, the association between Alpha 2CDel322-325 and CIC was confirmed (allele frequency, 0.33 vs 0.; P= 0.0001). In conclusion, Alpha 2CDel322-325 through the identification of patients at low risk of developing CIC can help physicians to better determine the most appropriate therapeutic approach, notably in patients at high risk of surgical complications.

Pituitary adenoma in patients with multiple endocrine neoplasia type 1: a cohort study.

OBJECTIVE: Pituitary adenoma (PA) is one of the three major components of multiple endocrine neoplasia type 1 (MEN1). Recent studies have suggested that MEN1-associated PAs are less aggressive than initially estimated. We propose an analysis of the outcome of PAs with a standard of care treatment in a nationwide cohort of MEN1 patients. DESIGN: Retrospective observational nationwide cohort study using the MEN1 patient registry from the French Group of Endocrine Tumours (GTE). METHODS: The GTE database population consists of 1435 patients with MEN1. This analysis focused on 551 patients recruited after 2000 with at least 3 years of follow-up. The study outcome was tumour progression of PA defined by an increase in Hardy classification (HC) during follow-up according to referring physician regular reports. RESULTS: Among 551 MEN1 patients (index and related), 202 (36.7%) had PA, with 114 (56.4%) diagnosed by MEN1-related screening. PAs were defined according to HC as microadenoma (grade I) in 117 cases (57.9%), macroadenoma in 59 (29.2%) with 20 HC grade II and 39 HC grades III-IV and unspecified in 26 (12.8%). They were prolactinomas in 92 cases (45.5%) and non-secreting in 73 (36.1%). After a median follow-up of 3 years among the 137 patients with HC grades I-II, 4 patients (2.9%) presented tumour progression. CONCLUSION: PAs in patients with MEN1 are less aggressive than previously thought. Tumour progression is rare with a standard of care monitoring and treatment, especially in related patients who mostly present non-secreting microadenoma. MRI monitoring for asymptomatic MEN1 patients should be reduced accordingly.

Phakomatoses and Endocrine Gland Tumors: Noteworthy and (Not so) Rare Associations.

Phakomatoses encompass a group of rare genetic diseases, such as von Hippel-Lindau syndrome (VHL), neurofibromatosis type 1 (NF1), tuberous sclerosis complex (TSC) and Cowden syndrome (CS). These disorders are due to molecular abnormalities on the RAS-PI3K-Akt-mTOR pathway for NF1, TSC and CS, and to hypoxia sensing for VHL. Phakomatoses share some phenotypic traits such as neurological, ophthalmological and cutaneous features. Patients with these diseases are also predisposed to developing multiple endocrine tissue tumors, e.g., pheochromocytomas/paragangliomas are frequent in VHL and NF1. All forms of phakomatoses except CS may be associated with digestive neuroendocrine tumors. More rarely, thyroid cancer and pituitary or parathyroid adenomas have been reported. These susceptibilities are noteworthy, because their occurrence rate, prognosis and management differ slightly from the sporadic forms. The aim of this review is to summarize current knowledge on endocrine glands tumors associated with VHL, NF1, TSC, and CS, especially neuroendocrine tumors and pheochromocytomas/paragangliomas. We particularly detail recent advances concerning prognosis and management, especially parenchyma-sparing surgery and medical targeted therapies such as mTOR, MEK and HIF-2 α inhibitors, which have shown truly encouraging results.

Genetic predisposition to neural crest-derived tumors: revisiting the role of KIF1B.

OBJECTIVE: We previously described a family in which predisposition to pheochromocytoma (PCC) segregates with a germline heterozygous KIF1B nucleotide variant (c.4442G>A, p.Ser1481Asn) in three generations. During the clinical follow-up, one proband's brother, negative for the KIF1B nucleotide variant, developed a bilateral PCC at 31 years. This prompted us to reconsider the genetic analysis. DESIGN AND METHODS: Germline DNA was analyzed by next-generation sequencing (NGS) using a multi-gene panel plus MLPA or by whole exome sequencing (WES). Tumor-derived DNA was analyzed by SnapShot, Sanger sequencing or NGS to identify loss-of-heterozygosity (LOH) or additional somatic mutations. RESULTS: A germline heterozygous variant of unknown significance in MAX (c.145T>C, p.Ser49Pro) was identified in the proband's brother. Loss of the wild-type MAX allele occurred in his PCCs thus demonstrating that this variant was responsible for the bilateral PCC in this patient. The proband and her affected grandfather also carried the MAX variant but no second hit could be found at the somatic level. No other pathogenic mutations were detected in 36 genes predisposing to familial PCC/PGL or familial cancers by WES of the proband germline. Germline variants detected in other genes, TFAP2E and TMEM214, may contribute to the multiple tumors of the proband. CONCLUSION: In this family, the heritability of PCC is linked to the MAX germline variant and not to the KIF1B germline variant which, however, may have contributed to the occurrence of neuroblastoma (NB) in the proband.

Frequency and Incidence of Carney Complex Manifestations: A Prospective Multicenter Study With a Three-Year Follow-Up.

INTRODUCTION: Carney Complex (CNC) is a rare multiple endocrine and nonendocrine neoplasia syndrome. Manifestations and genotype-phenotype correlations have been described by retrospective studies, but no prospective study evaluating the occurrence of the different manifestations has been available so far. METHODS: This multicenter national prospective study included patients with CNC, primary pigmented nodular adrenal disease (PPNAD), or a pathogenic PRKAR1A mutation; after a full initial workup, participants were followed for 3 years with annual standardized evaluation. RESULTS: The cohort included 70 patients (50 female/20 male, mean age 35.4 ± 16.7 years, 81% carrying PRKAR1A mutation). The initial investigations allowed identification of several manifestations. At the end of the 3-year follow-up, the newly diagnosed manifestations of the disease were subclinical acromegaly in 6 patients, bilateral testicular calcifications in 1 patient, and cardiac myxomas in 2 patients. Recurrences of cardiac myxomas were diagnosed in 4 patients during the 3-year follow-up study period. Asymptomatic abnormalities of the corticotroph and somatotroph axis that did not meet criteria of PPNAD and acromegaly were observed in 11.4% and 30% of the patients, respectively. Patients carrying the PRKAR1A c.709-7del6 mutation had a mild phenotype. CONCLUSION: This study underlines the importance of a systematic follow-up of the CNC manifestations, especially a biannual screening for cardiac myxoma. By contrast, regular screening for the other manifestations after a first extensive workup could be spread out, leading to a lighter and more acceptable follow-up schedule for patients. These are important results for recommendations for long-term management of CNC patients.

Metastatic Potential and Survival of Duodenal and Pancreatic Tumors in Multiple Endocrine Neoplasia Type 1: A GTE and AFCE Cohort Study (Groupe d'étude des Tumeurs Endocrines and Association Francophone de Chirurgie Endocrinienne).

OBJECTIVE: To assess the distant metastatic potential of duodeno-pancreatic neuroendocrine tumors (DP-NETs) in patients with MEN1, according to functional status and size. SUMMARY BACKGROUND DATA: DP-NETs, with their numerous lesions and endocrine secretion-related symptoms, continue to be a medical challenge; unfortunately they can become aggressive tumors associated with distant metastasis, shortening survival. The survival of patients with large nonfunctional DP-NETs is known to be poor, but the overall contribution of DP-NETs to metastatic spread is poorly known. METHODS: The study population included patients with DP-NETs diagnosed after 1990 and followed in the MEN1 cohort of the Groupe d'étude des Tumeurs Endocrines (GTE). A multistate Markov piecewise constant intensities model was applied to separate the effects of prognostic factors on 1) metastasis, and 2) metastasis-free death or 3) death after appearance of metastases. RESULTS: Among the 603 patients included, 39 had metastasis at diagnosis of DP-NET, 50 developed metastases during follow-up, and 69 died. The Markov model showed that Zollinger-Ellison-related tumors (regardless of tumor size and thymic tumor pejorative impact), large tumors over 2 cm, and age over 40 years were independently associated with an increased risk of metastases. Men, patients over 40 years old and patients with tumors larger than 2 cm, also had an increased risk of death once metastasis appeared. CONCLUSIONS: DP-NETs of 2 cm in size or more, regardless of the associated secretion, should be removed to prevent metastasis and increase survival. Surgery for gastrinoma remains debatable.

Should the GCM2 gene be tested when screening for familial primary hyperparathyroidism?

OBJECTIVE: Primary hyperparathyroism (PHPT) is a disease with either sporadic or inherited presentation. Germline mutations responsible for this disease can be found in different genes, the most frequently involved being MEN1, CDC73 = HRPT2 and CASR. During the last few years, new genes have been described as responsible for the development of PHPT such as GCM2. These genes are not systematically included in PHPT genetic screening yet. The aim of this work was to assess the importance of GCM2 genetic analysis in PHPT to determine if this gene should be included in gene panel investigated for this disease. DESIGN AND METHODS: The TENGEN network (French Oncogenetic Network of Neuroendocrine Tumors) collected and interpreted allelic variants according to the clinical characteristics of the GCM2-positive patients identified through genetic testing performed in French laboratories (713 patients with PHPT). RESULTS: From 713 patients with PHPT included in this study, 85 (6.6%) carried at least one GCM2 variant. A total of 12 variants classified as uncertain significance or likely pathogenic were reported in 47 patients. Their mean age at PHPT diagnosis was 49 years. Additionally, the investigation of a large family showed that GCM2 variants could be associated with low penetrance. CONCLUSION: We provide a description and interpretation for GCM2 variants identified in a French population. We suggest that this gene should be included in genetic screening of patients with PHPT and propose the follow-up of asymptomatic patients carrying such variants for calcemia.

A Full Phenotype of Paraganglioma Linked to a Germline SDHB Mosaic Mutation.

CONTEXT: Heterozygous germline pathogenic variants found in succinate dehydrogenase (SDH) complex genes predispose to hereditary paraganglioma (PGL) syndromes. No mosaicism has yet been reported in this setting. DESIGN AND PARTICIPANT: We describe the clinical history of a case of SDH complex, subunit B (SDHB) mosaicism. A 24-year-old woman who developed a cardiogenic shock during dental surgery was diagnosed with a functional para-aortic PGL, which produced predominantly norepinephrine and its metabolites. The tumor was removed and showed a loss of SDHB expression by immunohistochemistry. Four years after initial laparotomy, the patient had a rapid cardiac decompensation during her second pregnancy, despite negative imaging 10 months before. Two recurrent functional PGLs were found and surgically removed. Initial genetic analysis performed by Sanger sequencing did not reveal any germline pathogenic variant in SDHB, VHL, SDHD, SDHC, SDHAF2, RET, MAX, and TMEM127. Next-generation sequencing performed on tumor- and blood-extracted DNAs highlighted the presence of a mosaic rare variant in SDHB (c.557G>A, p.Cys186Tyr) with an allelic ratio of 15% in the blood DNA. CONCLUSIONS: We report the full clinical description of a proband with SDHB mosaicism associated with a functional, recurrent PGL. This case strengthens the necessity to complete the genetic analysis with methodologies able to identify germline mosaicism, especially in the case of early disease onset.

Targeted next-generation sequencing detects rare genetic events in pheochromocytoma and paraganglioma.

BACKGROUND: Knowing the genetic status of patients affected by paragangliomas and pheochromocytomas (PPGL) is important for the guidance of their management and their relatives. Our objective was to improve the diagnostic performances of PPGL genetic testing by next-generation sequencing (NGS). METHODS: We developed a custom multigene panel, which includes 17 PPGL genes and is compatible with both germline and tumour DNA screening. The NGS assay was first validated in a retrospective cohort of 201 frozen tumour DNAs and then applied prospectively to 623 DNAs extracted from leucocytes, frozen or paraffin-embedded PPGL tumours. RESULTS: In the retrospective cohort, the sensitivity of the NGS assay was evaluated at 100% for point and indels mutations and 86% for large rearrangements. The mutation rate was re-evaluated from 65% (132/202) to 78% (156/201) after NGS analysis. In the prospective cohort, NGS detected not only germline and somatic mutations but also co-occurring variants and mosaicism. A mutation was identified in 74% of patients for whom both germline and tumour DNA were available. CONCLUSION: The analysis of 824 DNAs from patients with PPGL demonstrated that NGS assay significantly improves the performances of PPGL genetic testing compared with conventional methods, increasing the rate of identified mutations and identifying rare genetic mechanisms.