IDH1 and glioblastoma: Given the fact that IDH-wild-type astrocytomas have similar behavior to GBM, WHO CNS5 defined as GBM IDH-wild-type CNS WHO grade 4 any IDH-wild-type astrocytomas with at least one of the following molecular characteristics: EGFR amplification, TERT promoter mutations, or gain of chromosome 7 and loss of chromosome 10 [12].