To present data on the high rate of SDHB mutations in patients with metastatic pheochromocytoma/paraganglioma whose initial tumor presentation began in childhood or adolescence.
From 2000 to 2010, ...263 patients with pheochromocytoma/paraganglioma were evaluated through the National Institutes of Health (NIH), Bethesda, MD. Of the 263 patients, 125 patients were found to have metastatic disease; of these 125 patients, 32 patients presented with a tumor before 20 years of age. An additional 17 patients presented with a tumor before 20 years of age but demonstrated no development of metastatic disease. Genetic testing for mutations in the VHL, MEN, and SDHB/C/D genes was performed on patients without previously identified genetic mutations.
Of the 32 patients who presented with metastatic disease and had their primary tumor in childhood or adolescence, sequence analysis of germline DNA showed SDHB mutations in 23 patients (71.9%), SDHD mutations in three patients (9.4%), VHL mutations in two patients (6.3%), and an absence of a known mutation in four patients (12.5%). The majority of these 32 patients (78.1%) presented with primary tumors in an extra-adrenal location.
The majority of patients with metastatic pheochromocytoma/paraganglioma who presented with a primary tumor in childhood/adolescence had primary extra-adrenal tumors and harbored SDHB mutations. Except for primary tumors located in the head and neck where SDHD genetic testing is advised, we recommend that patients who present with metastatic pheochromocytoma/paraganglioma with primary tumor development in childhood or adolescence undergo SDHB genetic testing before they undergo testing for other gene mutations, unless clinical presentation or family history suggests a different mutation.
Although pediatric pheochromocytomas and paragangliomas (PPGLs) are rare, they have important differences compared to those in adults. Unfortunately, without timely diagnosis and management, these ...tumors have a potentially devastating impact on pediatric patients. Pediatric PPGLs are more often extra-adrenal, multifocal/metastatic, and recurrent, likely due to these tumors being more commonly due to a genetic predisposition than in adults. This genetic risk results in disease manifestations at an earlier age giving these tumors time to advance before detection. In spite of these problematic features, advances in the molecular and biochemical characterization of PPGLs have heralded an age of increasingly personalized medicine. An understanding of the genetic basis for an individual patient’s tumor provides insight into its natural history and can guide clinicians in management of this challenging disease. In pediatric PPGLs, mutations in genes related to pseudohypoxia are most commonly seen, including the von Hippel-Lindau gene (
VHL
) and succinate dehydrogenase subunit (
SDHx
) genes, with the highest risk for metastatic disease associated with variants in
SDHB
and
SDHA
. Such pathogenic variants are associated with a noradrenergic biochemical phenotype with resultant sustained catecholamine release and therefore persistent symptoms. This is in contrast to paroxysmal symptoms (e.g., episodic hypertension, palpitations, and diaphoresis/flushing) as seen in the adrenergic, or epinephrine-predominant, biochemical phenotype (due to episodic catecholamine release) that is commonly observed in adults. Additionally, PPGLs in children more often present with signs and symptoms of catecholamine excess. Therefore, children, adolescents, and young adults present differently from older adults (e.g., the prototypical presentation of palpitations, perspiration, and pounding headaches in the setting of an isolated adrenal mass). These presentations are a direct result of genetic determinants and highlight the need for pediatricians to recognize these differences in order to expedite appropriate evaluations, including genetic testing. Identification and familiarity with causative genes inform surveillance and treatment strategies to improve outcomes in pediatric patients with PPGL.
Context:
Patients with von Hippel-Lindau (VHL) syndrome have a 25–30% chance of developing pheochromocytoma. Although practice guidelines recommend biochemical and radiological screening every 1–2 ...years for pheochromocytoma in patients with VHL, there are limited data on the optimal age and frequency for screening.
Objective:
Our objective was to determine the earliest age of onset and frequency of contralateral and recurrent pheochromocytomas in patients with VHL syndrome.
Methods:
This is a retrospective analysis of a prospective cohort of patients with VHL enrolled in a natural history study.
Results:
A total of 273 patients diagnosed with VHL were enrolled in a natural history clinical study. Thirty-one percent (84) were diagnosed with pheochromocytoma. The mean age of diagnosis was 28.8 ± 13.9 years. The earliest age at diagnosis was 5.5 years. Median follow-up for the cohort was 116.6 months (range, 0.1–613.2). Ninety-nine percent (83) of patients underwent adrenalectomy. Fifty-eight and 32% of patients had metanephrines and/or catecholamines elevated more than two times and more than four times the upper limit of normal, respectively. Twenty-five percent (21) of pheochromocytomas were diagnosed in pediatric patients younger than 19 years of age, and 86% and 57% of pediatric patients had an elevation more than two times and more than four times upper limit of normal, respectively. Eight patients had a total of nine recurrences. The median age at recurrence was 33.5 years (range, 8.8–51.9). Recurrences occurred as short as 0.5 years and as long as 39.7 years after the initial operation.
Conclusions:
Our findings among VHL pediatric patients supports the need for biochemical screening starting at age 5 with annual lifelong screening.
Complex II (CII) activity controls phenomena that require crosstalk between metabolism and signaling, including neurodegeneration, cancer metabolism, immune activation, and ischemia-reperfusion ...injury. CII activity can be regulated at the level of assembly, a process that leverages metastable assembly intermediates. The nature of these intermediates and how CII subunits transfer between metastable complexes remains unclear. In this work, we identify metastable species containing the SDHA subunit and its assembly factors, and we assign a preferred temporal sequence of appearance of these species during CII assembly. Structures of two species show that the assembly factors undergo disordered-to-ordered transitions without the appearance of significant secondary structure. The findings identify that intrinsically disordered regions are critical in regulating CII assembly, an observation that has implications for the control of assembly in other biomolecular complexes.
Purpose
Pheochromocytomas/paragangliomas (PHEOs/PGLs) are rare in children with only a few
SDHB
mutation-related cases. Previous studies on children were conducted in small cohorts. This large set of ...pediatric patients provides robust data in the evaluation of clinical outcomes.
Methods
Sixty-four pediatric PHEO/PGL patients with
SDHB
germline mutations were included in the present study. The clinical presentation, disease course, and survival rate were evaluated.
Results
Thirty-eight males and 26 females were diagnosed with PHEO/PGL at a median age of 13 years. The majority of patients displayed norepinephrine hypersecretion and 73.44% initially presented with a solitary tumor. Metastases developed in 70% of patients at the median age of 16 years and were mostly diagnosed first 2 years and in years 12–18 post-diagnosis. The presence of metastases at the time of diagnosis had a strong negative impact on survival in males but not in females. The estimated 5-, 10-, and 20-year survival rates were 100%, 97.14%, and 77.71%, respectively.
Conclusion
The present report has highlighted several important aspects in the management of pediatric patients with
SDHB
mutations associated-PHEO/PGL. Initial diagnostic evaluation of
SDHB
mutation carriers should be started at age of 5–6 years with initial work-up focusing on abdominal region. Thorough follow-up is crucial first 2 years post-diagnosis and more frequent follow-ups are needed in years 10–20 post-diagnosis due to the increased risk of metastases. Although this age group developed metastasis as early as 5 years from diagnosis, we have shown that the overall 20-year prognosis and survival are good.
Succinate dehydrogenase subunit B and D (SDHB and SDHD) mutations represent the most frequent cause of hereditary pheochromocytoma and paraganglioma (PPGL). Although truncation of the succinate ...dehydrogenase complex is thought to be the disease causing mechanism in both disorders, SDHB and SDHD patients exihibit different phenotypes. These phenotypic differences are currently unexplained by molecular genetics. The aim of this study is to compare disease dynamics in these two conditions via a Markov chain model based on 4 clinically-defined steady states. Our model corroborates at the population level phenotypic observations in SDHB and SDHD carriers and suggests potential explanations associated with the probabilities of disease maintenance and regression. In SDHB-related syndrome, PPGL maintenance seems to be reduced compared to SDHD (p = 0.04 vs 0.95) due to higher probability of tumor cell regression in SDHB vs SDHD (p = 0.87 vs 0.00). However, when SDHB-tumors give rise to metastases, metastatic cells are able to thrive with decreased probability of regression compared with SDHD counterparts (p = 0.17 vs 0.89). By constrast, almost all SDHD patients develop PGL (mainly head and neck) that persist throughout their lifetime. However, compared to SDHB, maintenance of metastatic lesions seems to be less effective for SDHD (p = 0.83 vs 0.11). These findings align with data suggesting that SDHD-related PPGL require less genetic events for tumor initiation and maintenance compared to those related to SDHB, but fail to initiate biology that promotes metastatic spread and metastatic cell survival in host tissues. By contrast, the higher number of genetic abnormalities required for tumor initiation and maintenance in SDHB PPGL result in a lower penetrance of PGL, but when cells give rise to metastases they are assumed to be better adapted to sustain survival. These proposed differences in disease progression dynamics between SDHB and SDHD diseases provide new cues for future exploration of SDHx PPGL behavior, offering considerations for future specific therapeutic and prevention strategies.
Hypoxia-inducible factors (HIFs) control the cellular response to hypoxia and, when dysregulated, contribute to tumorigenesis. Previously, we identified 2 gain-of-function somatic mutations in ...patients presenting with multiple paragangliomas or somatostatinomas, and polycythemia. Here, we report 2 additional unique HIF2A mutations, which disrupt the hydroxylation domain recognized by prolyl hydroxylase domain-2 containing protein, leading to stabilization of HIF-2α and increased expression of hypoxia-related genes.
•Newly identified mutations in HIF2A result in polycythemia and neuroendocrine tumors.•Disruption of the hydroxylation domain in HIF-2α results in protein stabilization, pseudohypoxia, and tumorigenesis.
Gaucher disease is caused by mutations of the GBA gene that encodes the lysosomal enzyme glucocerebrosidase (GCase). GBA mutations often result in protein misfolding and premature degradation, but ...usually exert less effect on catalytic activity. In this study, we identified the molecular mechanism by which histone deacetylase inhibitors increase the quantity and activity of GCase. Specifically, these inhibitors limit the deacetylation of heat shock protein 90, resulting in less recognition of the mutant peptide and GCase degradation. These findings provide insight into a possible therapeutic strategy for Gaucher disease and other genetic disorders by modifying molecular chaperone and protein degradation pathways.
The aim of this study was to determine whether the genetic background of the disease should be incorporated into treatment decision making.
Carotid body paragangliomas are rare tumors that often ...affect patients with genetic mutations of the succinate dehydrogenase complex (SDHx). Despite growing evidence that germ line genetic mutations alter the aggressiveness of paragangliomas, treatment decisions are currently based only on clinical symptoms and tumor size in patients with carotid body paragangliomas.
Retrospective analysis of 34 patients with carotid body paragangliomas who underwent genetic testing and surgical treatment. Recurrence was defined by the return of locoregional disease and/or development of distant metastases. Clinical characteristics and genetic testing results were analyzed as predictors of patient outcomes.
Thirty-four patients underwent 41 primary carotid body paraganglioma resections (median follow-up time of 42 months, range: 1-293). Overall survival was 91.2%. Twelve patients had germ line mutations in SDHB, 17 in SDHD, and 5 carried no known mutation. Surgical resection of larger tumors was associated with higher operative complications (odds ratio: 5.4, P = 0.05). Tumor size at resection was significantly smaller in patients with SDHB mutations than in patients with non-SDHB mutations (2.1 vs 3.3 cm, P = 0.02). Patients with a mutation in the SDHB gene also had significantly worse disease-free survival compared with patients without an SDHB gene mutation (P = 0.03).
Mutations in the SDHB gene are associated with worse disease-free survival after resection in patients with carotid body paragangliomas despite earlier intervention. This suggests that a more aggressive surgical approach is warranted in patients with SDHB mutations.
Cell growth and survival depend on a delicate balance between energy production and synthesis of metabolites. Here, we provide evidence that an alternative mitochondrial complex II (CII) assembly, ...designated as CII
, serves as a checkpoint for metabolite biosynthesis under bioenergetic stress, with cells suppressing their energy utilization by modulating DNA synthesis and cell cycle progression. Depletion of CII
leads to an imbalance in energy utilization and metabolite synthesis, as evidenced by recovery of the de novo pyrimidine pathway and unlocking cell cycle arrest from the S-phase. In vitro experiments are further corroborated by analysis of paraganglioma tissues from patients with sporadic, SDHA and SDHB mutations. These findings suggest that CII
is a core complex inside mitochondria that provides homeostatic control of cellular metabolism depending on the availability of energy.
PDF
