Following the initial discovery of isocitrate dehydrogenase (IDH) gene mutations in a small subset of especially younger glioblastoma patients with prolonged survival, a high percentage (70–80 %) of IDH1 and IDH2 mutations were identified in diffuse grade II and III gliomas, regardless of astrocytic or oligodendroglial cell type. Here, IDH2 is linked to central nervous system cancer.