Both mitotic count methods and Ki-67 proliferation index were significantly associated with the histological diagnosis, having mixed oligo-astrocytic tumors higher values compared to oligodendrogliomas and astrocytomas (Kruskal-Wallis test, P = 0.002 for H&E, P = 0.005 for PHH3 and P = 0.039 for Ki-67). The gene discussed is MKI67; the disease is oligodendroglioma.