IDH1 and glioblastoma: In addition, tumors that can be histologically classified as low-grade diffuse gliomas (i.e., without microvascular proliferation or necrosis) but have the IDH1/2 wild-type and all molecular features of GBM (EGFR amplification, combined Chr7 gain and Chr10 loss, or TERT promoter mutation) are now classified as GBM [1].