Consequently, the combination of telomerase reverse transcriptase (TERT) promoter mutation, epidermal growth factor receptor (EGFR) amplification, and/or copy number changes (+7/−10) in isocitrate dehydrogenase (IDH)-wildtype diffuse astrocytomas defines glioblastoma, IDH-wildtype CNS WHO grade 4, even in cases that microscopically resemble a lower grade [4]. The gene discussed is IDH1; the disease is diffuse astrocytoma.