The fifth edition of the WHO Classification of Tumors of the Central Nervous System (WHO CNS5), published in 2021, renamed glioblastoma as “glioblastoma, IDH-wild-type” (from now on referred to as GBM) and suggested supplementary guidelines for the histological classification of gliomas, indicating a spectrum of diagnostic, prognostic and/or predictive molecular biomarkers (Figure 1) [12]. The gene discussed is IDH1; the disease is glioblastoma.