For instance, it has become clear that patients with grade III 1p/19q co-deleted anaplastic oligodendrogliomas generally have a better prognosis than patients with other grade III glioma subtypes and that IDH1 mutant (secondary) glioblastomas tend to have a better outcome than IDH1 wild-type grade III astrocytomas [164]. This evidence concerns the gene IDH1 and oligodendroglioma.