Characterization of ATRX and TP53 variants along with 1p/19q codeletion testing results allow almost all cases of IDH-mutant gliomas to be diagnosed unambiguously as oligodendrogliomas or astrocytomas, with TERT promoter, CIC and FUBP1 variants adding further clarity [4, 7, 15, 18]. The gene discussed is IDH1; the disease is astrocytoma (excluding glioblastoma).