One of the most important discoveries in the studyof gliomas (including astrocytomas) was the identification of mutations in theIDH1 and IDH2 genes encodingNADP+-dependent homodimers of isocitrate dehydrogenases 1 and 2,which are localized in the cytoplasm and mitochondria, respectively, andcatalyze oxidative decarboxylation of isocitrate with the formation ofα-ketoglutarate (α-KG) [37].The IDH1 mutation is rarely found in primary glioblastomas( < 5%). The gene discussed is IDH2; the disease is astrocytoma (excluding glioblastoma).