IDH2 (isocitrate dehydrogenase [NADP] mitochondrial) catalyzes the conversion of isocitrate to alpha-ketoglutarate (alpha-KG). Mutations in IDH2 convert alpha-KG to 2-HG, which is an oncogenic metabolite. Simple variants in IDH2 are seen in about 3% of all tumors, including 1.5% of central nervous system tumors. Mutations in IDH2 are diagnostic for low grade glioma and secondary glioblastoma, and correlate with a better prognosis in glioblastoma. IDH2 inhibitors are also in development.