FH and cancer: Both metabolic reprogramming and epigenetic remodeling are established cancer hallmarks, and they reciprocally regulate each other.[37] It is now well established that mutations in certain mitochondrial enzymes alter epigenetic modification and promote tumorigenesis; these enzymes include isocitrate dehydrogenase 1/2 (IDH1/2), succinate dehydrogenase complex flavoprotein subunit A (SDHA), and fumarate hydratase (FH).[38, 39] However, known key players in epigenetic modification regulating mitochondrial metabolism are not well explored.