CDKN2A and glioblastoma: While CL-GBM shows frequent epidermal growth factor receptor (EGFR) amplification and cyclin-dependent kinase inhibitor 2A (CDKN2A) homozygous deletion, PN-GBM is associated with amplification of platelet-derived growth factor receptor alpha (PDGFRA) and tumor protein p53 (TP53) mutations.