When compared to IDH-wild type WHO Grade 4 gliomas (now designated glioblastomas), IDH-mutant WHO Grade 4 astrocytomas affect patients at a younger age at diagnosis (30–40 years vs. greater than 50 years) and have longer overall survival (31 vs. 13 months). The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).