The isocitrate dehydrogenase 1 (IDH-1) mutation, although not frequent, confers a good prognosis in histological GBM tumors; for that reason, these tumors are now classified as astrocytomas grade 4 IDH-1 mutant tumors in the new 2021 WHO classification [5,6]. The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).