Substitution point mutations in IDH1 (R132H) and IDH2 (R172K; R140Q) are common events in low-grade (II/III) glioma (> 75%) [66] and acute myeloid leukemias (AML) (20%) [67], but rare in other cancers [65]. The gene discussed is IDH2; the disease is acute myeloid leukemia.