This adjustment in terminology stems from growing evidence that IDH-mutant (grade 4) astrocytomas and IDH-wildtype glioblastomas clinically behave differently, with IDH-mutant tumours predicting a more favourable prognosis, and are characterized by distinct molecular alterations and epigenetic profiles [7,36,37]. This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).