IDH1 and glioblastoma: CNA molecular subtypes are defined by chromosome 1 gain, chromosome 19 gain, and CDK4/MDM2 co-amplification for the astrocytic glioma/glioblastoma, IDH-wildtype cluster (W1–W4), as well as CDK4 amplification, CDKN2A deletion, and chromosome 14 gain for the astrocytic glioma/glioblastoma, IDH-mutant cluster (M1–M3) (Fig. 6).