According to the new WHO Classification of Tumors of the Central Nervous System (WHO CNS5, Geneva, Switzerland, 2021), diffuse gliomas are categorized into three subgroups based on mutations in isocitrate dehydrogenase (IDH), 1p19q-codeletion status, and mutations in telomerase reverse transcriptase (TERT) (astrocytic, IDH-mutant; oligodendroglial, IDH-mutant, and 1p/19q-codeleted; glioblastoma (GBM), IDH-wildtype) [3]. This evidence concerns the gene TERT and glioblastoma.