According to this, the 2016 WHO brain tumor classification classified (anaplastic) astrocytoma based on the existence of IDH mutation, and the diagnosis of (anaplastic) oligodendroglioma requires coexistence of IDH mutation and 1p/19q co-deletion (Preusser and Marosi, 2017). The gene discussed is IDH2; the disease is astrocytoma (excluding glioblastoma).