Among the GBM molecular subtypes, the mesenchymal (MES) subtype, which harbors neurofibromin 1 (NF1) and RB transcription corepressor 1 (RB1) mutations, presents the poorest outcome, compared to the proneural (PN) subtype harboring somatic mutations in tumor protein p53 (TP53), platelet-derived growth factor receptor A (PDGFRA), and isocitrate dehydrogenase 1 (IDH1), and to the classical subtype with epidermal growth factor receptor (EGFR) mutations25,26. The gene discussed is RB1; the disease is glioblastoma.