IDH1 and diffuse astrocytoma: According to this classification, GBM diagnosis can be formulated even in presence of a histologically lower-grade glioma, if including one of the following alterations: CDKN2A/B homozygous deletion in IDH-mut astrocytomas, as well as pTERT-mut, EGFR-amp, and +7/−10 copy number changes in IDH-wt diffuse astrocytomas (49).