IDH2 and glioblastoma: GBM are now defined as diffuse, astrocytic gliomas that are IDH-wildtype and H3-wildtype, exhibiting one or more of the following histological or genetic features: microvascular proliferation, necrosis, telomerase reverse transcriptase (TERT) promoter mutation, epidermal growth factor receptor (EGFR) gene amplification, a concomitant gain of chromosome 7 and loss of chromosome 10 (+7/-10) (CNS WHO grade 4) (14, 16, 17).