IDH1 and glioblastoma: The 5th edition of the WHO classification of CNS tumors [5] classifies these gliomas primarily depending on the isocitrate dehydrogenase (IDH1/2) mutation status into three main types: IDH‐mutant astrocytoma; IDH‐mutant, 1p/19q co-deleted oligodendroglioma; and IDH‐wildtype glioblastoma.