IDH1 and oligodendroglioma: The majority of patients (n = 355) were diagnosed with a glioblastoma, IDH-wildtype, CNS WHO grade 4, while 46 patients had an Astrocytoma, IDH mutant, CNS WHO grade 2–4 and 25 patients were diagnosed with an Oligodendroglioma, IDH-mutant, CNS WHO grade 2 or 3.