Gliomas with succinate dehydrogenase deficiency: A case series and brief review of the literature of oncometabolite-driven gliomagenesis.

Oncometabolite production plays a key role in the development and progression of isocitrate dehydrogenase-mutant gliomas. The aberrant gain-of-function activity of the mutant isocitrate dehydrogenase protein results in the production of the oncometabolite D-2-hydroxyglutarate, which in turn promotes DNA hypermethylation and gliomagenesis through several mechanisms. Rare gliomas in patients with fumarate hydratase deficiency syndrome share many morphologic and molecular features with isocitrate dehydrogenase-mutant gliomas, with the oncometabolites succinate and 2-succinocysteine similarly thought to promote global DNA hypermethylation. Like isocitrate dehydrogenase and fumarate hydratase, succinate dehydrogenase is also a member of the citric acid cycle that additionally participates in oxidative phosphorylation. While succinate dehydrogenase deficiency has been implicated in familial tumor syndromes, it has not yet been associated with glial neoplasms. Here we report 3 cases of diffuse glioma with succinate dehydrogenase deficiency that show many similarities with isocitrate dehydrogenase-mutant gliomas. We propose that succinate dehydrogenase deficiency with accumulation of the oncometabolite succinate can promote gliomagenesis in a similar manner as seen in isocitrate dehydrogenase-mutant and fumarate hydratase-deficient gliomas, and we discuss the proposed mechanisms that may lead to tumor formation.