The former classification of adult-type diffuse gliomas has now been restructured into three distinct categories: astrocytoma, characterized by mutations in IDH without 1p/19q co-deletion; oligodendroglioma, with IDH mutations and 1p/19q co-deletion; and glioblastoma, IDH wild type [2,3]. The gene discussed is IDH2; the disease is glioblastoma.