Mutations in isocitrate dehydrogenase(IDH) 1 and IDH2 genes arefound in many cancers, with the most common cancer types associatedwith IDH1 and IDH2 mutations being gliomas and acute myeloid leukemia(AML), respectively.1,2 IDH1 localizes to the cytoplasm,while IDH2 localizes to mitochondria. The gene discussed is IDH2; the disease is central nervous system cancer.