IDH1 and glioma: Because grade II and III glioma commonly share similar genetic alterations, DGs are also commonly classified into lower-grade glioma (LGG) and glioblastoma (GBM)14,15, and then classified into 5 subgroups: LGG IDH-mutant and 1p/19-codeleted (LGG-IDHm-1p/19q); LGG IDH-mutant without 1p/19q codeletion (LGG-IDHm); LGG IDH-wildtype (LGG-IDHwt); GBM IDH-wildtype (GBM-IDHwt); and GBM IDH-mutant (GBM-IDHm)16–18.