Mutations in IDH1 and IDH2, frequently found in gliomas and acute myeloid leukemias (AML), are characterized by enzymatic gain of function and subsequent production of hydroxyglutarate, which inhibits several histone demethylases, including H3K9, H3K27, H3K36 and H3K4 [69]. The gene discussed is IDH2; the disease is glioma.