IDH1 and oligodendroglioma: Thereby, the degree of anaplasia is represented by the addition of a CNS WHO grade, depending on the degree of anaplasia, i.e., the presence of mitoses, microvascular proliferation, and necrosis: astrocytomas IDH mutated are graded as CNS WHO grade 2 to 4, oligodendrogliomas IDH mutated 1p/19q co-deleted are graded as CNS WHO grade 2 to 3, and glioblastomas IDH wildtype are graded as CNS WHO grade 4 [1].