Several molecular diagnostic markers have emerged in the 2021 CNS WHO classification, with powerful prognostic implications to consider when classifying diffuse IDH-mutant astrocytomas.1–3EGFR amplification status, associated with aggressive glioma behavior4 and now regarded as a molecular feature of glioblastoma, is not currently a diagnostic consideration in IDH-mutant astrocytomas.1 Although uncommon, IDH-mutant astrocytomas with EGFR amplification exist in large published datasets but their relevance has been under-emphasized and remains poorly understood.5–8. The gene discussed is IDH1; the disease is glioblastoma.