Glioblastomas are highly heterogeneous tumors with at least 3 identified transcriptional subtypes within the isocitrate dehydrogenase (IDH) WT glioblastomas: mesenchymal (MES), classical (CL), and proneural (PN) (3), which can coexist within a single tumor (4). The gene discussed is IDH3A; the disease is glioblastoma.