Patients with a proven IDH-wildtype, histologically grade II or III infiltrating astrocytoma and any of these alterations can be diagnosed with “Diffuse astrocytic glioma, IDH-wildtype, with molecular features of glioblastoma, WHO grade IV”, reflecting that their tumors are likely to behave in a manner similar to IDH-wildtype glioblastoma. The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).