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1. Recent clinical and fundamental research studies have revolutionized our understanding of the genetics of phaeochromocytoma (PH) and functional paraganglioma (FPGL). It was widely thought that only 10% of PH patients had familial disease and that the malignant phenotype of PH could not be diagnosed before occurrence of the first metastasis. 2. Human genetic studies have now shown that 25-30% of patients have hereditary PH due to a germline mutation in the SDHB, SDHD, VHL, RET or NF1 gene and that the identification of a germline SDHB mutation is associated with a high risk of malignancy and a poor prognosis in PH/PGL patients. 3. Fundamental research studies have shown that SDH genes are tumour suppressor genes and that succinate dehydrogenase inactivation induces abnormal stimulation of the hypoxia-angiogenesis pathway. 4. Finally various fundamental research studies, conducted through the Cortico and Medullo-surrenale: les Tumeurs Endocrines (COMETE) network in France and by other groups worldwide, have produced new recommendations for genetic counselling and testing and for the management of PH patients. They have also improved our understanding of the molecular mechanisms involved in PH tumorigenesis.
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PMID:Recent advances in the genetics of phaeochromocytoma and functional paraganglioma. 1830 24

Clinical and fundamental research based on the pheochromocytoma cohort of the COMETE network has drastically improved our knowledge of pheochromocytoma (PH). Previously, it was widely thought that only 10 % of PH patients had familial forms and that the malignant phenotype of PH could not be diagnosed before the first metastasis had already occurred. Genetic studies of the COMETE DNA collection contributed to showing that 25% to 30% of patients in fact have hereditary PH, due to a germline mutation of the SDHB, SDHD, VHL, RET or NF1 genes. The high-quality post-surgical clinical data collected by the COMETE network also show that SDHB germline mutations are a major risk factor for malignancy and poor outcome. Fundamental research work on the COMETE tumour collection shows that SDH genes are new tumour suppressor genes and that succinate dehydrogenase inactivation induces abnormal stimulation of the hypoxia-angiogenesis pathway. Since 2001, work by the COMETE network has led to new recommendations for genetic counselling and genetic testing in pheochromocytoma, and also for patient management. Finally, it has identified new molecular mechanisms involved in PH-related tumorigenesis.
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PMID:[Achievements of the COMETE program in the genetics of pheochromocytoma]. 1866 85

Familial renal cell carcinoma (RCC) is a heterogeneous disorder that is most commonly caused by germline mutations in the VHL, MET, and FLCN genes or by constitutional chromosome 3 translocations. However, for many patients with familial RCC, the genetic basis of the disease is undefined. We investigated whether germline mutations in fumarate hydratase (FH) or succinate dehydrogenase subunit genes (SDHB, SDHC, SDHD) were associated with RCC susceptibility in 68 patients with no clinical evidence of an RCC susceptibility syndrome. No mutations in FH, SDHC, or SDHD were identified in probands, but 3 of the 68 (4.4%) probands had a germline SDHB mutation. Patients with a germline SDHB mutation presented with familial RCC (n = 1) or bilateral RCC (n = 2) and no personal or family history of pheochromocytoma or head and neck paraganglioma. Age at diagnosis of RCC in SDHB mutation carriers ranged from 24 to 73 years. These findings 1) demonstrate that patients with suspected inherited RCC should be examined for germline SDHB mutations, 2) suggest that all identified SDHB mutation carriers should be offered surveillance for RCC, and 3) provide a further link between familial RCC and activation of hypoxic-gene response pathways.
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PMID:Germline SDHB mutations and familial renal cell carcinoma. 1872 80

Hereditary susceptibility to pheochromocytoma (PCC) and paraganglioma (PGL) represents a very complex genetic scenario. It has been reported that the absence of familial antecedents of the disease does not preclude the existence of a mutation affecting any of the five major susceptibility genes. In fact, 11-24% of apparently sporadic cases (without familial or syndromic antecedents) harbor an unexpected germline mutation, but we do not know what is happening in "truly apparently" sporadic patients (i.e., apparently sporadic cases diagnosed with only one tumor). In the present study, we have analyzed 135 apparently sporadic patients developing a single tumor for the five major susceptibility genes: VHL, RET, SDHB, SDHC, and SDHD. Fourteen percent of cases were found to harbor a germline mutation, and only 2.2% of patients were older than 45 years at onset. By taking into account the tumor location and a threshold age at onset of 45 years, we propose a rational scheme for genetic testing. Analyzing VHL and RET genes would be recommended only in young patients developing a single PCC. On the other hand, genetic testing of SDHD should be done in all patients developing an extra-adrenal tumor before the age of 45, and SDHC could be the responsible gene in cases developing a single head and neck tumor, independently of age. Finally, the analysis of SDHB should always be performed because of its association to malignancy and the low penetrance of mutations affecting this gene.
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PMID:Rationalization of genetic testing in patients with apparently sporadic pheochromocytoma/paraganglioma. 1934 21

The prevalence of germ line mutations within the RET-protooncogene and the tumor suppressor genes SDHB, SDHD, and VHL in pheochromocytomas (PC) varies in recent studies from 12 to 24%, if one look at them collectively. DNA was extracted from frozen tumor tissue as well as from blood leukocytes of 36 PC (26 sporadic/10 MEN2). Exons 1-8 of the SDHB-gene, 1-4 of the SDHD-gene, 1-3 of the VHL-gene, and exons 10, 11, 13, 14, 16 of the RET-gene were amplified by PCR and analyzed by DHPLC with the Transgenomic WAVE-System. Samples with aberrant wave profiles were subjected to direct sequencing. Genetic aberrations were correlated to clinical characteristics. Germ line mutations in sporadic PC were identified in four patients (11%) whereas somatic mutations were observed in two (5%) patients. Nine coding polymorphisms (PM) were identified in seven (19%) patients. Intronic variants were observed in six (17%) patients and were all located in the SHDB gene. Patients with wild type alleles in all assessed genes were older (53 vs. 37 years, P = 0.007) and presented with an increased tumor size (49 vs. 32 mm, P = 0.003) compared to patients with mutations. Malignant PC revealed multiple (>2) genetic alterations more frequently than benign PC (4/7 vs. 4/29, P = 0.03). Interestingly intronic variants of the SDHB gene occur more frequently in malignant than in benign PC (3/7 vs. 2/29, P = 0.04). The frequency of germ line mutations in sporadic pheochromocytomas was lower in our cohort than previously reported. Polymorphisms of the RET gene are common (17%) and occur in familial and sporadic PC. Multiple genetic alterations including mutations, polymorphisms and intronic variants are more frequently observed in malignant PC.
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PMID:Mutations and polymorphisms in the SDHB, SDHD, VHL, and RET genes in sporadic and familial pheochromocytomas. 1939 50

Pheochromocytomas/paragangliomas(PHEOs/PGLs) are rare but treacherous catecholamine-producing tumors which, if overlooked or improperly treated, will almost invariably prove fatal. Patients with MEN2 PHEOs have a high incidence of paroxysmal attacks and a higher prevalence of hypertension and other cardiovascular problems than do patients with Von-Hippel-Lindau (VHL) PHEOs. Compared to measurements of deconjugated metanephrines, plasma concentrations of free metanephrines are relatively independent of renal function and therefore more suitable for diagnosis of PHEO/PGL. Recently, the focus of Positron Emission Tomography (PET) imaging for these tumors has been the localization of PHEO. Although a limited number of studies are available, [18F]-fluorodopamine ([18F]DA) PET has been found to be the best overall imaging modality in the localization of PHEO. For adrenal PHEOs, this method seems to be comparable to other functional modalities such as [18F]-fluorodopa ([18F]DOPA) PET or [123I]-metaiodobenzylguanidine ([123I]MIBG)scintigraphy. For extraadrenal PHEOs, data are limited and more extensive studies are needed. In patients with metastatic PHEO, the sensitivity of [18F]DA PET is superior to [123I]MIBG. The so called "flip-flop" imaging showing superiority of non-specific [18F] flurodeoxyglucose (FDG) PET over specific [18F]DA PET has been described in rapidly progressive, often metastatic SDHB-associated PHEOs. Whether these data reflect PHEO cell dedifferentiation (e.g. losing Norepinephrine Transporter-NET) or increased metabolic rate remains to be established.
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PMID:Diagnosis of pheochromocytoma with special emphasis on MEN2 syndrome. 1957 Jul 38

Carney triad is a rare syndrome of unknown etiology characterized by having at least two out of three following neoplasms: gastrointestinal stromal tumor, pulmonary chondroma and extra-adrenal paraganglioma. About 100 cases have been reported worldwide. We report a case of Carney triad in a 42-year-old woman presented with a gastrointestinal stromal tumor in the stomach and a malignant functioning paraganglioma in the retroperitoneum that was fatal five years after diagnosis. The gastrointestinal stromal tumor was diagnosed as intermediate-risk of aggressive behavior and diffusely positive for c-kit whereas the retroperitoneal paraganglioma was negative for c-kit. Genetic analyses showed no mutations of KIT, PDGFRA, SDHB, SDHC, and SDHD genes in both tumors. To our best knowledge, this is the first case of Carney triad in Korea.
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PMID:Carney triad in an adult with aggressive behavior: the first case in Korea. 1988 77

Pheochromocytoma (pheo) is adrenal or less frequently extraadrenal tumour of chromafine tissue. Pheos are rare, but cardiovascular and metabolic abnormalities are common. Unrecognised pheo may lead to fatal hypertensive crisis during anesthesia or other stresses. Proper diagnosis of pheo is thus of utmost importance. 24-h blood pressure (BP) monitoring may contribute to the diagnosis of pheo due to increased BP variability and absence of night BP decline. Pheo contains large amount of enzyme catechol-O-methyl transpherase (COMT) with subsequent excessive production of COMT metabolites like metanephrines. Measurement of plasma free metanephrines or urinary fraccionated metanephrines has usually higher sensivitivity and specificity compared with plasma or urinary catecholamines. Morphological diagnosis of adrenal/extraadrenal pheo is based on CT/MR visualisation and 123I-metaiodobenzylguanidin (MIBG) or PET 18F-fluorodeoxyglucose scan. Genetic analysis should be performed in all confirmed pheo cases, especially in younger subjects below 50 years of age in order to detect mutations of following genes: von Hippel-Lindau (VHL), RET- protooncogen, genes encoding B, C and D subunit of mitochondrial sukcinat dehydrogenaze (SDHB, SDHC, SDHD) and neurofibromatosis type I gene. Pharmacological treatment is based on alpha blockers with subsequent (after 24-48 hours) administration of beta-blockers/especially in patients with tendency to tachycardia/. Following this therapy normalisation of BP is common and laparoscopic excision of pheo tumour can be realised. Malignant pheos are difficult to treat due to early occurrence of metastasis and lack of response to chemotherapy or iradiation in most cases.
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PMID:[Pheochromocytoma: diagnosis and treatment]. 1989 21

Up to 30% of pheochromocytomas and paragangliomas are associated with germline RET, Von Hippel-Lindau (VHL), neurofibromatosis type I (NF1), and succinate dehydrogenase subunits (SDHB, SDHC, and SDHD) mutations. Genetic testing allows familial counseling and identifies subjects at high risk of malignancy (SDHB mutations) or significant multiorgan disease (RET, VHL, or NF1). However, conventional genetic testing for all loci is burdensome and costly. We performed immunohistochemistry for SDHB on 58 tumors with known SDH mutation status. We defined positive as granular cytoplasmic staining (a mitochondrial pattern), weak diffuse as a cytoplasmic blush lacking definite granularity, and negative as completely absent staining in the presence of an internal positive control. All 12 SDH mutated tumors (6 SDHB, 5 SDHD, and 1 SDHC) showed weak diffuse or negative staining. Nine of 10 tumors with known mutations of VHL, RET, or NF1 showed positive staining. One VHL associated tumor showed weak diffuse staining. Of 36 tumors without germline mutations, 34 showed positive staining. One paraganglioma with no known SDH mutation but clinical features suggesting familial disease was negative, and one showed weak diffuse staining. We also performed immunohistochemistry for SDHB on 143 consecutive unselected tumors of which 21 were weak diffuse or negative. As SDH mutations are virtually always germline, we conclude that approximately 15% of all pheochromocytomas or paragangliomas are associated with germline SDH mutation and that immunohistochemistry can be used to triage genetic testing. Completely absent staining is more commonly found with SDHB mutation, whereas weak diffuse staining often occurs with SDHD mutation.
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PMID:Immunohistochemistry for SDHB triages genetic testing of SDHB, SDHC, and SDHD in paraganglioma-pheochromocytoma syndromes. 2023 88

Pheochromocytoma (PCC) and paraganglioma (PGL) are tumors of the autonomic nervous system. The former is a tumor that occurs in only adrenal glands, and the latter can be found in the head and neck or in the thorax and abdomen. In PCC and PGL, genetic mutations account for approximately 30% of functional (secrete catecholamines) and nonfunctional cases. In addition to RET, VHL and NF-1, genes encoding succinate dehydrogenase complex subunit B (SDHB), subunit C (SDHC), and subunit D (SDHD) are recognized as susceptibility genes for PCC and PGL. Recently, PCC and PGL caused by genetic mutations of SDHB, SDHC and SDHD were established as hereditary pheochromocytoma paraganglioma syndrome (HPPS). Approximately 15% of all PCCs and PGLs are recognized as HPPS. Among these three susceptibility genes, SDHB and SDHD are known to be strongly related to HPPS. The aim of this study was to analyze SDHB and SDHD mutations in PCC and PGL patients. Among 18 patients, we identified a novel heterozygous nonsense mutation at codon 168 resulting in a CAG (glutamine) to TAG (stop) substitution (Q168X) in the SDHB gene in a patient diagnosed with solitary sporadic PGL. A number of studies have reported that SDHB mutation-associated disease demonstrates a higher rate of malignancy. However, all seven patients diagnosed with malignancy in this study did not have genetic mutation of SDHB and only one patient with no malignant sign had genetic mutation of SDHB. Further accumulation of cases is necessary to confirm the association between SDHB mutation and malignant potential.
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PMID:Mutation analysis of the SDHB and SDHD genes in pheochromocytomas and paragangliomas: identification of a novel nonsense mutation (Q168X) in the SDHB gene. 2050 58


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