Dataset Information

Novel and recurrent genetic variants of VHL, SDHB, and RET genes in Chinese pheochromocytoma and paraganglioma patients.

ABSTRACT: Background: Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors arising from chromaffin cells in the adrenal medulla and extra-adrenal ganglia, respectively. The study was aimed to investigate the clinical and genetic characteristics of 22 individuals from six families. Methods: The medical records of six PPGL probands who presented to our hospital between 2016 and 2021 were retrospectively studied. DNA isolated from the probands was analyzed using whole exome sequencing. The identified genetic variants were confirmed by Sanger sequencing and undergone bioinformatic analysis. Results: Six different genetic variants in the six probands were identified, respectively, of which three were novel. A novel von Hippel-Lindau (VHL) variant, c.602T>C (p.L201P), in exon 3 was found. Two novel genetic variants in SDHB (succinate dehydrogenases subunit B), c.423 + 1 G>T and c.662A>G (p.D221G), were identified. Two recurrent genetic variants of VHL, c.C284G (p.P95R) and c.558_560AGAdel (p.186Edel), and one in RET (ret proto-oncogene), c.1901G>A (p.C634Y), were also found. The ClinVar accession number for the present variants are SCV002028348, and SCV002028352 to SCV002028361. Conclusion: Genetic variants in VHL, SDHB and RET were identified in Chinese PPGL patients, which contributed to the knowledge of the genetic etiology and clinical outcome of these tumors.

SUBMITTER: Li C

PROVIDER: S-EPMC10020357 | biostudies-literature | 2023

REPOSITORIES: biostudies-literature

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Novel and recurrent genetic variants of VHL, SDHB, and RET genes in Chinese pheochromocytoma and paraganglioma patients.

Li Chong C Li Jingyi J Han Chao C Wang Ting T Zhang Lixia L Wang Zhifang Z Wang Tingting T Xu Lijun L Qi Guangzhao G Qin Guijun G Li Xialian X Zheng Lili L

Frontiers in genetics 20230303

Background: Pheochromocytoma and paraganglioma (PPGL) are rare neuroendocrine tumors arising from chromaffin cells in the adrenal medulla and extra-adrenal ganglia, respectively. The study was aimed to investigate the clinical and genetic characteristics of 22 individuals from six families. Methods: The medical records of six PPGL probands who presented to our hospital between 2016 and 2021 were retrospectively studied. DNA isolated from the probands was analyzed using whole exome ...[more]

PMID: 36936415

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Project description:Pheochromocytoma/paraganglioma (PPGL) is an endocrine tumor of the chromaffin cells in the adrenal medulla or the paraganglia. Currently, about 70% of PPGLs can be explained by germline or somatic mutations in several broadly expressed susceptibility genes including RET, VHL, and SDHB, while for the remaining, mainly sporadic cases, the pathogenesis is still unclear. Even for known susceptible genes, how mutations in these mostly ubiquitous genes result in tissue-specific pathogenesis remains unanswered, and why RET-mutated tumors almost always occur in the adrenal while SDHB-mutated tumors mostly occur extra-adrenal remains a mystery. By analyzing 22 sporadic PPGLs using SNP 6.0 genotyping arrays combined with expression profiling of 4 normal and 4 tumor tissues, we identified GIPC2, a gene located at 1p31.1 with preferential expression in adrenal and inducible by adrenal glucocorticoid, as a novel putative tumor suppressor gene for PPGLs. Copy number deletion and GIPC2 promoter hypermethylation but not GIPC2 mutation, accompanied with reduced GIPC2 expression, were observed in 39 of 55 PPGLs in our cohort. Examination of a published expression database consisting of 188 PPGLs found little GIPC2 expression in Cluster 1A (SDHx-associated) and Cluster 2A (NF1/RET-associated) tumors, but less pronounced reduction of GIPC2 expression in Cluster 1B (VHL-associated) and Cluster 2B/2C tumors. GIPC2 induced p27, suppressed MAPK/ERK and HIF-1ɑ pathways as well as cancer cell proliferation. Overexpressing GIPC2 in PC12 cells inhibited tumor growth in nude mice. We found GIPC2 interacted with the nucleoprotein NONO and both proteins regulated p27 transcription through the same GGCC box on p27 promoter. Significantly, low expression of both GIPC2 and p27 was associated with shorter disease-free survival time of PPGLs patients in the TCGA database. We found that PPGL-causing mutations in RET and in SDHB could lead to primary rat adrenal chromaffin cell proliferation, ERK activation, and p27 downregulation, all requiring downregulating GIPC2. Notably, the RET-mutant effect required the presence of dexamethasone while the SDHB-mutant effect required its absence, providing a plausible explanation for the tumor location preference. In contrast, the PPGL-predisposing VHL mutations had no effect on proliferation and GIPC2 expression but caused p53 downregulation and reduced apoptosis in chromaffin cells compared with wild-type VHL. Thus, our study raises the importance of cortical hormone in PPGL development, and GIPC2 as a novel tumor suppressor provides a unified molecular mechanism for the tumorigenesis of both sporadic and hereditary tumors of Clusters 1A and 2A concerning SDHB and RET, but not tumors of Cluster 1B concerning VHL and other clusters.

Project description:Pheochromocytoma and paragangliomas (PPGLs) are rare neuroendocrine tumors carrying 25-40% pathogenic germline gene variants (PGVs). We evaluated clinical, laboratory, and germline molecular profile of 115 patients with pathologic (14 patients were relatives from 8 different families recruited for genetic survey) confirmed PPGL followed in our institution. Patients with classic MEN2A/MEN2B phenotypes and at-risk relatives underwent direct analysis of RET proto-oncogene, and the remaining had samples submitted to complete next-generation sequencing aiming 23 PPGL-related genes: ATM, ATR, CDKN2A, EGLN1, FH, HRAS, KIF1B, KMT2D, MAX, MDH2, MERTK, MET, NF1, PIK3CA, RET, SDHA, SDHAF2, SDHB, SDHC, SDHD, TMEM127, TP53, and VHL. We also developed a clinical judgment score (CJS) to determine the probability of patients having a potentially hereditary disease. The resulting genetic landscape showed that 67 patients (58.3%) had variants in at least one gene: 34 (50.7%) had exclusively pathogenic or likely pathogenic variants, 13 (19.4%) had pathogenic or likely pathogenic variants and variant of undetermined significance (VUS), and 20 (29.8%) carried only VUS. PGVs were found in RET (n = 18; 38.3%), VHL (n = 10; 21.3%), SDHB and NF1 (n = 8; 17% each), and MAX, SDHD, TMEM127, and TP53 (n = 1; 2.1% each). Direct genetic testing disclosed 91.3% sensitivity, 81.2% specificity, and 76.4% and 93.3% positive predictive value (PPV) and negative predictive values (NPV), respectively. The CJS to identify patients who would not benefit from genetic testing had 75% sensitivity, 96.4% specificity, and 60% and 98.2% PPV and NPV, respectively. In summary, the landscape of PPGL germline gene variants from 115 Brazilian patients resulted in slightly higher prevalent pathogenic and likely pathogenic variants, especially in the RET gene. We suggest a CJS to identify PPGL patients who would not require initial genetic evaluation, improving test specificity and reducing costs.

Project description:Abstract Background: SDHB immunostaining can be used to functionally characterize SDH status in PCC and PGL. Assessing SDHB expression on tumors is inexpensive and can be used as an alternative to genetic testing. More importantly, assessment of SDHB expression can be of value in interpreting Variant of Unknown Significance (VUS) in SDH related genes. Objective: To investigate the effectiveness of SDHB immunostaining as an initial screening tool in identifying germline SDH mutations and the value of SDHB assessment in the clinical characterization of our patient cohort. Design: Prospective and retrospective analysis of 57 randomly selected patients with PCC and PGL from the year 1997 to 2018. Setting: In our institution on patients referred from London and South East England including Kent, Surrey and Sussex. Patients: Predominant Caucasian Population with diverse ethnicities. 57 patients - 34 patients (14M & 20F) with PGL and 25 with PCC (15M &10F). Age (mean: 41years at diagnosis with range 9-80 years). 2 patients had both PCC & PGL and multifocal PGLs were identified in few patients with SDHD and SDHB mutation. There were 65 tumors in total included in this study. Intervention: Resected tumor SDHB immunostaining with Sigma prestige antibodies (HPA002868 100UL - Anti-SDHB Rabbit monoclonal antibody) at a dilution of 1:1000. Genetic testing performed on predominant candidate genes. Main outcome measures: Concordance of SDHB loss of expression with presence of pathogenic mutation in candidate SDH genes. Secondarily, to explore SDHB immunostaining in our patient cohort with VUS in candidate genes. Results: SDHB immunostaining was negative in 22/23 tumors in patients with confirmed SDH mutation (false negative = 1 SDHB PCC where it was weak (+)). The staining was positive in 23/24 sporadic tumors, 10/11 VUS (in SDH, MAX and TMEM genes - both PCCs & PGLs), 2/2 PCCs in MEN-2, 2/2 PCCs in NF-1 and 2/3 PCCs in VHL. The negative immunostaining in 1 PGL with VUS in SDHB may imply lack of SDH enzyme activity and hence suggestive of a pathological mutation. The sensitivity is 96% and the specificity approaches 93% if the weak positive SDHB immunostaining with SDHD and VHL tumors were to be considered concordant. The concordance was 95% in the PGL group alone. Conclusions: SDHB immunostaining is a cost effective addition to PGL and PCC tumor characterization and performs with high sensitivity and specificity. SDH functional characterization has an important role in the management of patients who do not satisfy the current criteria for genetic testing (UK genetics testing directory for PCC/PGL). 18% of patients had VUS in a SDH related gene and we have found that SDHB immunostaining provided helpful information to inform follow-up and cascade screening decisions in this group.

Project description:IntroductionPheochromocytomas and paragangliomas (PCC/PGL) are rare neuroendocrine tumors and can secrete catecholamine. Previous studies have found that SDHB immunohistochemistry (IHC) can predict SDHB germline gene mutation, and SDHB mutation is closely associated with tumor progression and metastasis. This study aimed to clarify the potential effect of SDHB IHC as a predictive marker for tumor progression in PCC/PGL patients.MethodsWe included PCC/PGL patients diagnosed in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from 2002 to 2014 for retrospective analysis and discovered that SDHB (-) staining patients had poorer prognoses. Then we examined SDHB protein expression by IHC on all tumors in the prospective series, which was composed of patients from 2015 to 2020 in our center.ResultsIn the retrospective series, the median follow-up was 167 months, and during follow-up, 14.4% (38/264) patients developed metastasis or recurrence, and 8.0% (22/274) patients died. Retrospective analysis revealed that 66.7% (6/9) of participants in the SDHB (-) group and 15.7% (40/255) of those in the SDHB (+) group developed progressive tumors (OR: 10.75, 95% CI: 2.72-52.60, P=0.001), and SDHB (-) was independently associated with poor outcomes after adjusting by other clinicopathological parameters (OR: 11.68, 95% CI: 2.58-64.45, P=0.002). SDHB (-) patients had shorter disease-free survival (DFS) and overall survival (OS) (P<0.001) and SDHB (-) was significantly associated with shorter median DFS (HR: 6.89, 95% CI: 2.41-19.70, P<0.001) in multivariate cox proportional hazard analysis. In the prospective series, the median follow-up was 28 months, 4.7% (10/213) patients developed metastasis or recurrence, and 0.5% (1/217) patient died. For the prospective analysis, 18.8% (3/16) of participants in the SDHB (-) group had progressive tumors compared with 3.6% (7/197) in the SDHB (+) group (RR: 5.28, 95% CI: 1.51-18.47, P=0.009), statistical significance remained (RR: 3.35, 95% CI: 1.20-9.38, P=0.021) after adjusting for other clinicopathological factors.ConclusionsOur findings demonstrated patients with SDHB (-) tumors had a higher possibility of poor outcomes, and SDHB IHC can be regarded as an independent biomarker of prognosis in PCC/PGL.

Dataset Information

Novel and recurrent genetic variants of VHL, SDHB, and RET genes in Chinese pheochromocytoma and paraganglioma patients.

Publications

Novel and recurrent genetic variants of <i>VHL</i>, <i>SDHB</i>, and <i>RET</i> genes in Chinese pheochromocytoma and paraganglioma patients.

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