Germline c.1A>C heterozygous pathogenic variant in SDHA reported for the first time in a young adult with a gastric gastrointestinal stromal tumour (GIST): a case report

BACKGROUND: Gastrointestinal stromal tumors (GISTs) represent the most frequent mesenchymal tumor of the gastrointestinal tract. Less than 5% of them seem to be hereditary, being succinate dehydrogenase complex (SDHx) deficient disorders and neurofibromatosis type 1 the more related inherited conditions. Wild type (WT) KIT and PDGFRα GISTs constitute a clue for a hypothetical underlying germline condition. CASE PRESENTATION: We present a case of a 20 years old female diagnosed of a gastric WT GIST who developed hepatic metastases during her clinical course. No significant or typical phenotypic features suggestive of a specific syndrome were detected by physical examination. Also, her family history seemed to be irrelevant, since no other cases of GISTs, paragangliomas or pheochromocytomas were reported. Her paternal grandfather died as a consequence of a pituitary adenoma. In light of the age of tumor presentation and somatic features of gastric GIST, we performed genetic testing of SDHx genes. Analysis obtained from peripheral blood sample revealed the presence, in heterozygous state, of the c.1A > C; p.(Met1?) pathogenic variant in the SDHA. CONCLUSIONS: To the best of our knowledge, this is the first published report in which the c.1A > C; p.(Met1?) pathogenic variant in the SDHA is associated with a GIST. SDHA pathogenic variants increase the risk of paraganglioma, pheochromocytoma, GIST, pituitary adenoma and renal cancer in an autosomal dominant inherited condition named paraganglioma syndrome type 5. The absence of family history of tumors in SDHA pathogenic variants carriers could be related to its low penetrance. All patients diagnosed with WT GISTs should be referred to a hereditary cancer genetic counseling unit regardless of the age at presentation or the absence of a suspicious family history.