A separate group of adult diffuse gliomas characterized by activating IDH1 (IDH1mut) or IDH2 (IDH2mut) mutations comprise 1p/19q intact astrocytomas and 1p/19q co-deleted oligodendrogliomas, with varying grades (II-IV) and survival rates [89], further displaying, e.g., PDGFRA and CDK4 amplification, CDKN2A/B deletion, ATRX, TP53, or TERT promoter mutations [60, 83, 116], as well as a glioma CpG Island Methylator Phenotype (G-CIMP) [33, 79]. This evidence concerns the gene CDKN2A and astrocytoma (excluding glioblastoma).