Hereditary Paraganglioma Syndrome Research Articles

Synchronous adrenocortical neoplasms, paragangliomas, and pheochromocytomas: syndromic considerations regarding an unusual constellation of endocrine tumors

The most common clinical syndromes presenting with paragangliomas and/or pheochromocytomas as their endocrine components are multiple endocrine neoplasia type 2, neurofibromatosis, Von Hippel-Lindau syndrome, Carney-Stratakis syndrome, Carney triad, and the recently described hereditary paraganglioma syndrome. Only Carney triad is known to also present with adrenocortical adenomas, currently representing the only described syndrome in which all 3 of the aforementioned tumors are found together. In most cases, prototypical lesions of the triad such as gastrointestinal stromal tumor and pulmonary chondromas are also seen. We present a case of a young woman with synchronous paragangliomas, adrenal/extra-adrenal cortical neoplasms, and pheochromocytoma without genetic mutations for multiple endocrine neoplasia 2, Von Hippel-Lindau syndrome, neurofibromatosis, and succinate dehydrogenase. We speculate that this represents a previously undescribed presentation of Carney triad and, at the very least, indicates the need for monitoring for the development of other tumors of the triad.

Succinate dehydrogenase gene mutations and DNA methylation analysis in hereditary pheochromocytoma paraganglioma syndrome

Objective To detect the genetic mutations of succinate dehydrogenase B (SDHB),SDHC,SDHD,SDHAF2 and RET,VHL in hereditary pheochromocytoma (PHEO) paraganglioma (PGL) syndrome in order to analyze the relationship between the pathogenesis and SDHx mutations and DNA methylation.Methods SDH genes,VHL and RET were analyzed for germline mutations in 97 PHEOs/PGLs patients.Correlations were analyzed between the results and the clinical characteristics including age,tumor localization,multifocality,24 h urine CA,IGF and NSE.Direct DNA sequence analysis was carried out for SDHB (1q36.1-1q35,exons1-8),SDHC (1q21,exons 1-5),SDHD (11q23,exons 1-4),SDHAF2 (11q12.2,exons 1-4),RET (10q11.2,exons10,11,13,14&15,and 16) and VHL (3p25.3,exons 1-3) genes,and promoter region methylation of SDHB was detected in PHEO/PGL peripheral blood samples.Results Germinal mutations were found in 17 patients (17.5％),with 8 cases in RET proto-oncogene (8.2％),7 cases in SDHB genes (7.2％) and 2 cases in VHL gene (2.1％).The comparison of some of the clinical features in two groups (with and without promoter region methylation of SDHB) showed significant differences (P＜0.01).Conclusions Genetic predisposition is frequent in chromaffin tissue tumors,indicating that DNA analysis is necessary.The mutation of SDHB is highly associated with abdominal PGL and the following distant metastasis (malignant PGL). Key words: Pheochromocytomas; Paragangliomas; Succinate dehydrogenase; DNA mutational analysis; DNA methylation

Predisposition to pediatric and hematologic cancers: a moving target.

Our understanding of hereditary cancer syndromes in children, adolescents, and young adults continues to grow. In addition, we now recognize the wide variation in tumor spectrum found within each specific cancer predisposition syndrome including the risk for hematologic malignancies. An increased understanding of the genetic mutations, biologic consequences, tumor risk, and clinical management of these syndromes will improve patient outcome. In this article, we illustrate the diversity of molecular mechanisms by which these disorders develop in both children and adults with a focus on Li-Fraumeni syndrome, hereditary paraganglioma syndrome, DICER1 syndrome, and multiple endocrine neoplasia syndrome. This is followed by a detailed discussion of adult-onset tumors that can occur in the pediatric population including basal cell carcinoma, colorectal cancer, medullary thyroid cancer, and adrenal cortical carcinoma, and the underlying hereditary cancer syndromes that these tumors could indicate. Finally, the topic of leukemia predisposition syndromes is explored with a specific focus on the different categories of syndromes associated with leukemia risk (genetic instability/DNA repair syndromes, cell cycle/differentiation, bone marrow failure syndromes, telomere maintenance, immunodeficiency syndromes, and transcription factors/pure familial leukemia syndromes). Throughout this article, special attention is made to clinical recognition of these syndromes, genetic testing, and management with early tumor surveillance and screening.

The clinical phenotype of SDHC-associated hereditary paraganglioma syndrome (PGL3).

Mutations in the genes encoding subunits of the succinate dehydrogenase complex cause hereditary paraganglioma syndromes. Although the phenotypes associated with the more commonly mutated genes, SDHB and SDHD, are well described, less is known about SDHC-associated paragangliomas. To describe functionality, penetrance, number of primary tumors, biological behavior, and location of paragangliomas associated with SDHC mutations. Families with an SDHC mutation were identified through a large cancer genetics registry. A retrospective chart review was conducted with a focus on patient and tumor characteristics. In addition, clinical reports on SDHC-related paragangliomas were identified in the medical literature to further define the phenotype and compare findings. A cancer genetics clinic and registry at a tertiary referral center. Eight index patients with SDHC-related paraganglioma were identified. Three of the eight index patients had mediastinal paraganglioma and four of the eight patients had more than one paraganglioma. Interestingly, the index patients were the only affected individuals in all families. When combining these index cases with reported cases in the medical literature, the mediastinum is the second most common location for SDHC-related paraganglioma (10% of all tumors), occurring in up to 13% of patients. Our findings suggest that thoracic paragangliomas are common in patients with SDHC mutations, and imaging of this area should be included in surveillance of mutation carriers. In addition, the absence of paragangliomas among at-risk relatives of SDHC mutation carriers suggests a less penetrant phenotype as compared to SDHB and SDHD mutations.

Phenotypic Variability and Risk of Malignancy inSDHC-Linked Paragangliomas: Lessons From Three Unrelated Cases With an Identical Germline Mutation (p.Arg133*)

Mutations in the four subunits of succinate dehydrogenase (SDH) are the cause for the hereditary paraganglioma (PGL) syndrome types 1-4 and are associated with multiple and recurrent pheochromocytomas and PGLs. SDHC mutations most frequently result in benign, nonfunctional head-and neck PGLs (HNPGLs). The malignant potential of SDHC mutations remains unclear to date. We report a patient with malignant PGL carrying a SDHC mutation and compare her case with two others of the same genotype but presenting with classic benign HNPGLs. Loss of heterozygosity (LOH) was demonstrated in the malignant PGL tissue. In three unrelated patients referred for routine genetic testing, SDHB, SDHC, and SDHD genes were sequenced, and gross deletions were excluded by multiplex ligation-dependent probe amplification (MLPA). LOH was determined by pyrosequencing-based allele quantification and SDHB immunohistochemistry. In a patient with a nonfunctioning thoracic PGL metastatic to the bone, the lungs, and mediastinal lymph nodes, we detected the SDHC mutation c.397C>T predicting a truncated protein due to a premature stop codon (p.Arg133*). We demonstrated LOH and loss of SDHB protein expression in the malignant tumor tissue. The two other patients also carried c.397C>T, p.Arg133*; they differed from each other with respect to their tumor characteristics, but both showed benign HNPGLs. We describe the first case of a malignant PGL with distant metastases caused by a SDHC germline mutation. The present case shows that SDHC germline mutations can have highly variable phenotypes and may cause malignant PGL, although malignancy is probably rare.

No difference in phenotype of the main Dutch SDHD founder mutations

SDHD mutations predispose carriers to hereditary paraganglioma syndrome. The objective of this study was to assess the genotype-phenotype correlation of a large Dutch cohort of SDHD mutation carriers and evaluate potential differences in clinical phenotypes due to specific SDHD gene mutations. Retrospective, descriptive single-centre study. All consecutive SDHD mutation carriers followed at the Department of Endocrinology of the Leiden University Medical Center were included. Subjects were investigated according to structured protocols used for standard care, including repetitive biochemical and radiological screening for paragangliomas. Two hundred and one SDHD mutation carriers with a mean age at presentation of 42·6 ± 14·4 years and a mean follow-up of 5·8 ± 5·4 years were evaluated. Eighty-one percent carried the SDHD c.274G>T (p.Asp92Tyr) mutation and 13% the SDHD c.416T>C (p.Leu139Pro) mutation. No differences in clinical phenotype between these two specific SDHD mutations were found. Ninety-one percent developed one or multiple paragangliomas in the head and neck region (HNPGLs), of which the carotid body tumour was the most prevalent (85%). Eighteen carriers developed pheochromocytomas, fifteen sympathetic paragangliomas and nine carriers (4%) suffered from malignant paraganglioma. By end of follow-up, sixteen SDHD mutation carriers (8%) displayed no biochemical or radiological evidence of manifest disease. The two main Dutch SDHD founder mutations do not differ in clinical expression. SDHD mutations are associated with the development of multiple HNPGLs and predominantly benign disease.

Definition of a new algorithm for molecular-genetic testing of patients with hereditary pheochromocytoma and paraganglioma syndromes

Definition of a new algorithm for molecular-genetic testing of patients with hereditary pheochromocytoma and paraganglioma syndromes

High incidence of extraadrenal paraganglioma in families with SDHx syndromes detected by functional imaging with [18F]fluorodihydroxyphenylalanine PET

Knowledge of the genetic backgrounds of hereditary syndromes, which are increasingly being characterized, enables genetic screening of family members of affected patients. Upon detection of a mutation, genetic counselling and clinical screening including imaging modalities and biochemical analyses are commonly performed. Unaffected, mutation-positive relatives of index patients with hereditary paraganglioma syndromes were offered PET imaging with [(18)F]fluorodihydroxyphenylalanine and the incidence of pathological findings was retrospectively analysed in relation to mutations of the succinate dehydrogenase enzyme complex. PET only or PET/CT was performed in 21 individuals from eight families with SDHD, one family with SDHC and two families with SDHB mutations. Screening was offered every 2 to 5 years. Of the 21 individuals, 14 showed paraganglioma during screening. In particular, in only 2 of 15 patients with a SDHD mutation were the findings completely unremarkable on PET screening. However, false-negative lesions for abdominal manifestations in two SDHD-positive patients were detected. FDOPA PET is a sensitive imaging modality which should be offered to patients with a detected SDHx (SDHD) mutation, preferably using a hybrid technique.

Peptide Receptor Radionuclide Therapy (PRRT) with 177Lu-DOTATATE in Individuals with Neck or Mediastinal Paraganglioma (PGL)

Paragangliomas (PGLs) are neuroendocrine tum-ors that arise embryologically from the neural crest. Sympathetic PGLs can be located in the thoracic-abdominal region while parasympathetic PGLs are mainly situated in the head and neck region. Most PGLs are sporadic, but in 30% of cases they are hereditary (associated with mutations of SDHB, SDHC, SDHD, SDHAF2, SDHA, TMEM, MAX, and VHL); they can be classified into 4 different paraganglioma syndromes: PGL1, PGL2, PGL3, and PGL4. Surgery is the treatment of choice for both sympathetic and parasympathetic PGLs. Other types of treatment include medical agents (such as gemcitabine, cisplatin, or sunitinib) and radiotherapy (external-beam radiotherapy or stereotactic surgery). Surgery and radiotherapy, however, can cause important side effects such as vascular complications and peripheral nerve damage (hypoglossal, recurrent laryngeal, glossopharyngeal, and vagus). Another possible treatment option is the use of peptide receptor radionuclide therapy (PRRT), including PRRT with 177Lu-DOTATATE. We studied 4 patients with hereditary nonmetastatic paraganglioma syndrome type 1 (PGL1), with progressive disease, in whom surgical excision was not possible. They were treated with 177Lu-DOTATATE (3-5 cycles) and all had a partial response (PR) or a stable disease (SD) to the treatment. In conclusion, a good alternative treatment when surgical or radiation therapy are contraindicated could be radiometabolic therapy with 177Lu-DOTATATE.

High prevalence of founder mutations of the succinate dehydrogenase genes in the Netherlands

Mutations in four genes encoding subunits or cofactors of succinate dehydrogenase (SDH) cause hereditary paraganglioma and pheochromocytoma syndromes. Mutations in SDHB and SDHD are generally the most common, whereas mutations in SDHC and SDHAF2 are far less frequently observed. A total of 1045 DNA samples from Dutch paraganglioma and pheochromocytoma patients and their relatives were analyzed for mutations of SDHB, SDHC, SDHD or SDHAF2. Mutations in these genes were identified in 690 cases, 239 of which were index cases. The vast majority of mutation carriers had a mutation in SDHD (87.1%). The second most commonly affected gene was SDHAF2 (6.7%). Mutations in SDHB were found in only 5.9% of samples, whereas SDHC mutations were found in 0.3% of samples. Remarkably, 69.1% of all carriers of a mutation in an SDH gene in the Netherlands can be attributed to a single founder mutation in SDHD, c.274G>T and p.Asp92Tyr. Moreover, 88.8% of all SDH mutation carriers carry one of just six Dutch founder mutations in SDHB, SDHD and SDHAF2. The dominance of SDHD mutations is unique to the Netherlands, contrasting with the higher prevalence of SDHB mutations found elsewhere. In addition, we found that most SDH mutation-related paragangliomas-pheochromocytomas in the Netherlands can be explained by only six founder mutations in SDHAF2, SDHB and SDHD. The findings underline the regional differences in the SDH mutation spectrum, differences that should be taken into account in the development of effective screening protocols. The results show the crucial role that demographic factors play in the frequency of gene mutations.

Hereditary Paraganglioma Syndrome Associated with SDHD Gene Mutations: A Patient with Multicentric Presentation Treated with Radiotherapy. Case Report

Extra-adrenal paragangliomas are rare tumors arising from neuroendocrine cells. Sporadic and hereditary forms have been recognized. Among the latter, the PGL1 and PGL4 syndromes are associated with a high risk of multiple localizations. The treatment of choice for paragangliomas is surgical resection, but in some cases surgery can be difficult due to particular or multiple tumor sites or may result in severe neurological deficits. In such cases radiotherapy can be an effective alternative. In this paper we describe the case of a patient affected by hereditary paraganglioma syndrome with multicentric presentation who was treated at our center by external radiotherapy. A 55-year-old man presented in April 2008 with multiple paragangliomas: one in the left pontocerebellar angle, two in the middle neck, one mediastinal paraaortic mass, and an abdominal paraaortic lesion. The left pontocerebellar and mediastinal tumors were treated with three-dimensional conformal radiotherapy (3D-CRT) at total doses of 50.40 Gy and 55.80 Gy, respectively. The neck lesions were treated with intensity-modulated radiotherapy (IMRT) at a total dose of 55.80 Gy. The abdominal paraaortic lesion was surgically resected. No severe acute or late toxicity as evaluated with the EORTC-RTOG scale was observed. Fourteen months after the end of radiotherapy a whole body CT scan showed that the tumor lesions were stable in size and in their relations to contiguous structures. The arterial pressure was controlled by medical therapy and urine catecholamine levels were within the normal range. We believe that in patients affected by unresectable paragangliomas radiotherapy is a safe and effective alternative to surgery. The use of high-dose conformity techniques such as 3D-CRT and IMRT will allow higher local control rates with relatively few side effects thanks to the possibility of dose escalation and reduction of the amount of irradiated healthy tissues.

Novel germline SDHD mutation: diagnosis and implications to the patient

A 54-year-old man presented with hypertensive crisis. He was found to have bilateral pheochromocytomas and left paraaortic sympathetic paraganglioma. Although he had no family history of paragangliomas or pheochromocytomas, he had been diagnosed with bilateral head and neck paragangliomas 10years prior. The patient had symptoms of catecholamine excess exacerbated by vanilla ice-cream consumption. Biochemical testing revealed elevated plasma-free metanephrines and chromogranin A levels. Computed tomography showed bilateral carotid body tumors and four reteroperitoneal masses (two in the right adrenal, one in the left adrenal and one in the left paraaortic area). Metaiodobenzylguanidine-SPECT scans showed functional tumors in both the adrenal gland and left paraaortic area. Fluorine 18-fluorodeoxyglucose positron emission tomography did not show any visceral or skeletal metastasis. We carried out gene mutation analysis for succinate dehydrogenase complex subunit B, and succinate dehydrogenase complex subunit D. The patient was diagnosed with hereditary paraganglioma syndrome type 1 with a previously unreported subunit D mutation in exon 3 (c.198G>A, p.W66X). He was treated with phenoxybenzamine at 10mg/day and with metoprolol at 12.5mg/day. His blood pressures as well as symptoms of catecholamine excess were controlled. He then underwent bilateral adrenalectomy and reteroperitoneal dissection. His blood pressure normalized and he discontinued antihypertensive medications after surgery. He is currently on replacement therapy with hydrocortisone and fludrocortisone.

Adrenal cortical tumors, pheochromocytomas and paragangliomas

Distinguishing adrenal cortical adenomas from carcinomas may be a difficult diagnostic problem. The criteria of Weiss are very useful because of their reliance on histologic features. From a practical perspective, the most useful criteria to separate adenomas from carcinomas include tumor size, presence of necrosis and mitotic activity including atypical mitoses. Adrenal cortical neoplasms in pediatric patients are more difficult to diagnose and to separate adenomas from carcinomas. The diagnosis of pediatric adrenal cortical carcinoma requires a higher tumor weight, larger tumor size and more mitoses compared with carcinomas in adults. Pheochromocytomas are chromaffin-derived tumors that develop in the adrenal gland. Paragangliomas are tumors arising from paraganglia that are distributed along the parasympathetic nerves and sympathetic chain. Positive staining for chromogranin and synaptophysin is present in the chief cells, whereas the sustentacular cells are positive for S100 protein. Hereditary conditions associated with pheochromocytomas include multiple endocrine neoplasia 2A and 2B, Von Hippel–Lindau disease and neurofibromatosis I. Hereditary paraganglioma syndromes with mutations of SDHB, SDHC and SDHD are associated with paragangliomas and some pheochromocytomas.

Hereditäre und nichthereditäre syndromale gastrointestinale Stromatumoren

The majority of gastrointestinal stromal tumours (GISTs) present as solitary gastrointestinal masses in adults aged 50-70years. A small subset of GISTs (≤5%) occurs in the setting of familial or idiopathic multitumour syndrome. In decreasing order of frequency, neurofibromatosis Recklinghausen (NF-1), Carney triad (gastric GIST, pulmonary chondroma and extra-adrenal paraganglioma), familial GIST syndromes resulting from germline mutations in c-Kit/PDGFRA and the Carney-Stratakis syndrome (hereditary GIST paraganglioma syndrome caused by germline mutations in the mitochondrial tumour suppressor gene pathway involving the succinate dehydrogenase subunits SDHD, SDHC and SDHB) represent the four most important GIST syndromes characterized to date. Since affected patients and their family members require special treatment and/or counseling and follow-up, early diagnosis and precise classification of this likely still underdiagnosed diseases is of the utmost importance. This review summarizes the pertinent clinicopathological and molecular features of the main GIST syndromes to facilitate their diagnosis and distinction from their non-syndromic mimics.

An unusual tumor spectrum in Lynch syndrome caused by MSH6 mutation

Background Inherited cancer syndromes associated with acoustic neuroma (i.e. neurofibromatosis 2-NF2), pheochromocytoma (i.e. Von Hippel Lindau, NFl, multiple endocrine neoplasia syndromes, and hereditary paraganglioma syndrome), and colon cancer are well known. Lynch syndrome is the most common hereditary colon cancer syndrome and is caused by DNA mismatch repair dysfunction secondary to inherited mutations in one of MLHl, MSH2, MSH6, and less commonly PMS2. An increased risk for a variety of cancers is seen in patients with Lynch syndrome with the greatest risks being for colon and endometrial cancer. We report a Dutch patient with a history of bilateral acoustic neuromas diagnosed at 47, and pheochromocytoma and endometrial adenocarcinoma diagnosed at age 54. She had no family history or other signs/symptoms of NF2. Family history was significant for her brother having metachronous colon cancers at 42 and 51, and a maternal uncle having colon cancer in his 40s. The family does not fulfill either Amsterdam I or II criteria.

Mutation analysis of the SDHB and SDHD genes in pheochromocytomas and paragangliomas: identification of a novel nonsense mutation (Q168X) in the SDHB gene

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.

Laparoscopic Excision of a Familial Paraganglioma

Pheochromocytomas are rare neuroendocrine tumors that secrete catecholamines and usually arise from the adrenal medulla. Catecholamine-producing tumors that arise from extra-adrenal chromaffin tissue are referred to as paragangliomas, or extra-adrenal pheochromocytomas. Contrary to the traditional "Rule of Tens," as many as 25% of pheochromocytomas occur in hereditary tumor syndromes, such as multiple endocrine neoplasia-2, von Hippel-Lindau disease, neurofibromatosis-1, or hereditary or familial paraganglioma syndrome. Surgical resection remains the only curative therapy for pheochromocytomas, and advances in minimally invasive techniques have shown laparoscopic adrenalectomy to be safe and effective. Paragangliomas are extremely rare tumors, especially in children, and the role of laparoscopy in their treatment is evolving. This case report and the accompanying video demonstrate that the laparoscopic approach to retroperitoneal paraganglioma resection provides excellent exposure of the tumor and surrounding structures. Given proper patient preparation and perioperative monitoring, laparoscopic exploration and resection of paragangliomas can be safely and successfully accomplished in children. In addition, genetic analysis should be considered for all patients presenting with these tumors.

SDHB-associated renal oncocytoma suggests a broadening of the renal phenotype in hereditary paragangliomatosis

Mutations in SDHB are one of the causes of hereditary paraganglioma syndrome. Germline mutations in SDHB predispose to the development of head and neck paragangliomas and phaeochromocytomas. Renal tumours are also increasingly being reported as component tumours in hereditary paragangliomatosis associated with mutations in SDHB. We present the first reported case of a family in whom an individual shown to carry a mutation in SDHB developed a renal oncocytoma. We review other reports of renal tumours associated with SDHB-associated hereditary paragangliomatosis and suggest that various histological subtypes of renal tumours are part of this condition. This observation indicates that SDHB-associated hereditary paragangliomatosis is unlike most tumour predisposition syndromes associated with the development of renal tumours which are usually associated with specific histological sub-types. The increasing recognition of the involvement of renal tumours in SDHB mutation carriers suggests that renal screening is likely to be valuable for these patients. SDHB mutations should also be considered in the context of genetic testing when renal tumours, regardless of histopathology, present in families with other tumours consistent hereditary paraganglioma syndrome.

Diagnosis and management of hereditary paraganglioma syndrome due to the F933>X67 SDHD mutation

The hereditary paraganglioma syndromes (PGLs) are autosomal dominant conditions with an increased risk for tumors of the sympathetic and parasympathetic neuroendocrine systems. The recognition of patients with hereditary PGL and identification of the responsible gene are important for the management of index patients and family members. We present the clinical, radiological, biochemical, and family history findings of a 15-year-old boy patient with a glomus vagale versus glomus jugulare tumor. Evaluation of the family history and the patient's history led to the identification of a familial succinate dehydrogenase subunit D (SDHD) gene mutation (F933>X67), consistent with a diagnosis of hereditary PGL1. Although this family had all head and neck tumors, this SDHD mutation has previously been described in a family with primarily functional pheochromocytomas. This case report highlights the variable expressivity of a single mutation in SDHD, (F933>X67). Careful and comprehensive screening is warranted for individuals at risk.

Mutations associated with succinate dehydrogenase d‐related malignant paragangliomas

Hereditary paraganglioma (PGL) syndromes result from germline mutations in genes encoding subunits B, C and D of the mitochondrial enzyme succinate dehydrogenase (SDHB, SDHC and SDHD). SDHB-related PGLs are known in particular for their high malignant potential. Recently, however, malignant PGLs were also reported among a small minority of Dutch carriers of the SDHD founder mutation D92Y. The aim of the study was to investigate which SDHD mutations are associated with malignant PGL. Case histories; collaborative study between referral centres in France, the USA, and the Netherlands. Six unrelated patients with metastatic PGLs of either sympathetic or parasympathetic origin. Assessment of SDHD mutations underlying malignant PGL. Germline SDHD mutations underlying metastatic PGL were G148D, Y114X, L85X, W43X, D92Y, and IVS2+5G-->A. Our findings indicate that malignant SDHD-related PGL is associated with several mutations besides D92Y.