According to the 2021 WHO Classification of Tumors of the Central Nervous System (Louis et al., 2021), in which the term glioblastoma designates only IDH-wildtype grade 4 tumors, we will hence use the term grade 4 glioma, as we included as well IDH-mutant grade 4 tumors (Supplementary file 1). This evidence concerns the gene IDH1 and glioma.