IDH1 and ependymoma: The most common tumors Glioblastoma, IDH-wild-type (CNS WHO grade 4) (39/73; 53.4%), followed by Astrocytoma, IDH mutant (CNS WHO grade 4) (8/73; 11%), Oligodendroglioma, IDH mutant and 1p/19q-codeleted (CNS WHO grade 3) (7/73; 9.6%), Astrocytoma, IDH mutant (CNS WHO grade 3) (4/73; 5.5%), Astrocytoma, IDH mutant (CNS WHO grade 2) (4/73; 5.5%), Oligodendroglioma, IDH mutant and 1p/19q-codeleted (CNS WHO grade 2) (3/73; 4.1%) and ependymoma (3/73; 4.1%) (Figure 1A+B).