Co-occurrence of mutations in NF1 and other susceptibility genes in pheochromocytoma and paraganglioma

Co-occurrent mutations; Germline mutation; PheochromocytomaMutaciones concurrentes; Mutación de la línea germinal; FeocromocitomaMutacions concurrents; Mutació de la línia germinal; FeocromocitomaIntroduction: The percentage of patients diagnosed with pheochromocytoma and paraganglioma (altogether PPGL) carrying known germline mutations in one of the over fifteen susceptibility genes identified to date has dramatically increased during the last two decades, accounting for up to 35-40% of PPGL patients. Moreover, the application of NGS to the diagnosis of PPGL detects unexpected co-occurrences of pathogenic allelic variants in different susceptibility genes. Methods: Herein we uncover several cases with dual mutations in NF1 and other PPGL genes by targeted sequencing. We studied the molecular characteristics of the tumours with co-occurrent mutations, using omic tools to gain insight into the role of these events in tumour development. Results: Amongst 23 patients carrying germline NF1 mutations, targeted sequencing revealed additional pathogenic germline variants in DLST (n=1) and MDH2 (n=2), and two somatic mutations in H3-3A and PRKAR1A. Three additional patients, with somatic mutations in NF1 were found carrying germline pathogenic mutations in SDHB or DLST, and a somatic truncating mutation in ATRX. Two of the cases with dual germline mutations showed multiple pheochromocytomas or extra-adrenal paragangliomas - an extremely rare clinical finding in NF1 patients. Transcriptional and methylation profiling and metabolite assessment showed an “intermediate signature” to suggest that both variants had a pathological role in tumour development. Discussion: In conclusion, mutations affecting genes involved in different pathways (pseudohypoxic and receptor tyrosine kinase signalling) co-occurring in the same patient could provide a selective advantage for the development of PPGL, and explain the variable expressivity and incomplete penetrance observed in some patients.This work was supported by the Instituto de Salud Carlos III (ISCIII), through the “Acción Estratégica en Salud” (AES) (projects PI18/00454 to AC and PI20/01169 to MR), cofounded by the European Regional Development Fund (ERDF). SM was supported by the Spanish Ministry of Science, Innovation and Universities “Formación del Profesorado Universitario— FPU” fellowship with ID number FPU19/04940

Targeted exome sequencing of Krebs cycle genes reveals candidate cancer–predisposing mutations in pheochromocytomas and paragangliomas

Purpose: Mutations in Krebs cycle genes are frequently found in patients with pheochromocytomas/paragangliomas. Disruption of SDH, FH or MDH2 enzymatic activities lead to accumulation of specific metabolites, which give rise to epigenetic changes in the genome that cause a characteristic hypermethylated phenotype. Tumors showing this phenotype, but no alterations in the known predisposing genes, could harbor mutations in other Krebs cycle genes. Experimental Design: We used downregulation and methylation of RBP1, as a marker of a hypermethylation phenotype, to select eleven pheochromocytomas and paragangliomas for targeted exome sequencing of a panel of Krebs cycle-related genes. Methylation profiling, metabolite assessment and additional analyses were also performed in selected cases. Results: One of the 11 tumors was found to carry a known cancer-predisposing somatic mutation in IDH1. A variant in GOT2, c.357A>T, found in a patient with multiple tumors, was associated with higher tumor mRNA and protein expression levels, increased GOT2 enzymatic activity in lymphoblastic cells, and altered metabolite ratios both in tumors and in GOT2 knockdown HeLa cells transfected with the variant. Array methylation-based analysis uncovered a somatic epigenetic mutation in SDHC in a patient with multiple pheochromocytomas and a gastrointestinal stromal tumor. Finally, a truncating germline IDH3B mutation was found in a patient with a single paraganglioma showing an altered a-ketoglutarate/ isocitrate ratio. Conclusions: This study further attests to the relevance of the Krebs cycle in the development of PCC and PGL, and points to a potential role of other metabolic enzymes involved in metabolite exchange between mitochondria and cytosolThis work was supported by the Fondo de Investigaciones Sanitarias project PI15/00783, FEDER 2014-2020 (to A. Cascon) and the Deutsche Forschungs- gemeinschaft (grant RI 2684/1-1; to S. Richter). CEGEN-PRB2-ISCIII is supported by grant PT13/0001, ISCIII-SGEFI/FEDE

Co-occurrence of mutations in NF1 and other susceptibility genes in pheochromocytoma and paraganglioma

IntroductionThe percentage of patients diagnosed with pheochromocytoma and paraganglioma (altogether PPGL) carrying known germline mutations in one of the over fifteen susceptibility genes identified to date has dramatically increased during the last two decades, accounting for up to 35-40% of PPGL patients. Moreover, the application of NGS to the diagnosis of PPGL detects unexpected co-occurrences of pathogenic allelic variants in different susceptibility genes.MethodsHerein we uncover several cases with dual mutations in NF1 and other PPGL genes by targeted sequencing. We studied the molecular characteristics of the tumours with co-occurrent mutations, using omic tools to gain insight into the role of these events in tumour development.ResultsAmongst 23 patients carrying germline NF1 mutations, targeted sequencing revealed additional pathogenic germline variants in DLST (n=1) and MDH2 (n=2), and two somatic mutations in H3-3A and PRKAR1A. Three additional patients, with somatic mutations in NF1 were found carrying germline pathogenic mutations in SDHB or DLST, and a somatic truncating mutation in ATRX. Two of the cases with dual germline mutations showed multiple pheochromocytomas or extra-adrenal paragangliomas - an extremely rare clinical finding in NF1 patients. Transcriptional and methylation profiling and metabolite assessment showed an “intermediate signature” to suggest that both variants had a pathological role in tumour development.DiscussionIn conclusion, mutations affecting genes involved in different pathways (pseudohypoxic and receptor tyrosine kinase signalling) co-occurring in the same patient could provide a selective advantage for the development of PPGL, and explain the variable expressivity and incomplete penetrance observed in some patients

Diferencias entre cáncer de mama familiar asociado a mutación germinal en BRCA1 o BRCA2 y el no asociado a mutación: estudio inmunohistoquímico y fish mediante matrices de tejido

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid. Facultad de Medicina. Departamento de Anatomía Patológica. Fecha de lectura: 21-12-200

The Pathology of Hereditary Breast Cancer

Abstract Several studies have demonstrated that familial breast cancers associated with BRCA1 or BRCA2 germline mutations differ in their morphological and immunohistochemical characteristics. Cancers associated with BRCA1 are poorly differentiated infiltrating ductal carcinomas (IDCs) with higher mitotic counts and pleomorphism and less tubule formation than sporadic tumours. In addition, more cases with the morphological features of typical or atypical medullary carcinoma are seen in these patients. Breast carcinomas from BRCA2 mutation carriers tend to be of higher grade than sporadic age-matched controls. Regarding immunophenotypic features. BRCA1 tumours have been found to be more frequently oestrogen receptor- (ER) and progesterone receptor-(PR) negative, and p53-positive than age-matched controls, whereas these differences are not usually found in BRCA2-associated tumours. A higher frequency and unusual location of p53 mutations have been described in BRCA1/2 carcinomas. Furthermore, BRCA1- and BRCA2-associated breast carcinomas show a low frequency of HER-2 expression. Recent studies have shown that most BRCA1 carcinomas belong to the basal cell phenotype, a subtype of high grade, highly proliferating ER/HER2-negative breast carcinoma characterized by the expression of basal or myoepithelial markers, such as basal keratins, P-cadherin, EGFR, etc. This phenotype occurs with a higher incidence in BRCA1 tumours than in sporadic carcinomas and is rarely found in BRCA2 carcinomas. Hereditary carcinomas not attributable to BRCA1/2 mutations have phenotypic similarities with BRCA2 tumours, but tend to be of lesser grade and lower proliferation index. The pathological features of hereditary breast cancer can drive specific treatment and influence the process of mutation screening.</p