Taking IDH-mutation status into consideration, WHO grade was reported as a significant factor for OS in lower-grade gliomas11,24,25, and one of the studies showed that WHO grade had higher prognostic value in IDH-wild-type astrocytomas compared with in IDH-mutant astrocytomas, with the authors proposing histological mitotic count as a significant predictor of prognosis24. The gene discussed is IDH2; the disease is astrocytoma (excluding glioblastoma).