Cancer-associated IDH1 and IDH2 mutations occur almost exclusively at different arginine residues in the active site of the enzyme.793 IDH1 and IDH2 mutations occur in a wide variety of hematologic and solid tumors, including glioma, AML, intrahepatic cholangiocarcinoma, chondrosarcoma, thyroid cancer, and angioimmunoblastic T cell lymphoma.793–795 Mutant IDH1/2 catalyzes the conversion of α-KG to D-2-hydroxyglutarate (D2HG). The gene discussed is IDH1; the disease is cancer.