For WHO grade II/III gliomas, three molecular subgroups have been defined: IDH wild-type glioma (IDHwt) with survival similar to that of glioblastoma, IDH-mutant glioma with intact 1p19q (IDHmut1p19int) and an intermediate prognosis, and IDH-mutant 1p19q co-deleted glioma (IDHmut1p19qdel) with the best prognosis and greatest chemosensitivity [11]. The gene discussed is IDH1; the disease is central nervous system cancer.