Three types of adult-type diffuse gliomas are also recognized in the most recent edition of the WHO CNS tumor classification (2021): astrocytoma, IDH-mutant; oligodendrogllioma, IDH-mutant and 1p19q-codeleted; and glioblastoma, IDH-wildtype [4]. The gene discussed is IDH2; the disease is astrocytoma (excluding glioblastoma).