IDH1 and oligodendroglioma: Three types of gliomas were defined: IDH mutant gliomas, further divided into astrocytomas IDH mutant (whose diagnosis was based on the absence of 1p/19q co-deletion and the presence of an IDH mutation) and oligodendrogliomas IDH mutant and 1p/19q co-deleted, and IDH-wildtype gliomas, primarily represented by glioblastomas, IDH-wildtype.