IDH1 and astrocytoma (excluding glioblastoma): Adult-type diffuse gliomas are split into three groups: (i) grade 4 isocitrate dehydrogenase 1/2 wildtype (IDHwt) glioblastoma (GBM); (ii) grade 2–4 IDH1/2 mutant (IDHmut) astrocytoma; (iii) grade 2–3 IDH mutant (IDHmut) oligodendroglioma [3].