Genetic alterations in some mitochondrial metabolic enzymes, such as fumarate hydratase (FH), succinate dehydrogenase (SDH), and isocitrate dehydrogenase (IDH), result in the accumulation of fumarate, succinate, and 2‐hydroxyglutarate, which promote tumorigenesis and have become promising targets for tumor therapy [121]. The gene discussed is IDH2; the disease is neoplasm.