According to the World Health Organization (WHO) classification of Central Nervous System (CNS) tumors (WHO CNS5), gliomas can be divided into three types: oligodendroglioma with IDH mutation and 1p/19q deletion (mut+codel), astrocytoma with IDH mutation and 1p/19q non-codeletion (mut+non-codel), and glioblastoma with IDH-widetype. The gene discussed is IDH1; the disease is oligodendroglioma.