While managing CNS WHO grade 4 glioma patients in clinical practice, physicians encounter certain cases in which the prognosis of patients with IDH-mutant astrocytoma CNS WHO grade 4 is worse than that of patients with IDH-wildtype glioblastoma CNS WHO grade 4, even though IDH mutations are a good prognostic factor for gliomas. This evidence concerns the gene IDH2 and glioblastoma.