The 4 molecular subgroups exhibited further differences in their anatomical localization patterns: IDH1/2-mutant gliomas (astrocytomas and oligodendrogliomas) predominantly occupied the cerebral hemispheres (89.4% and 97.8%, respectively), with minimal cerebellar involvement (1.1% and 0.7%, respectively). The gene discussed is IDH1; the disease is oligodendroglioma.