However, one report did note varied expression of Olig1 and Olig2. Here, the authors found 3 grade III oligodendrogliomas did not express either Olig1 or Olig2 while another 3 grade III oligodendrogliomas expressed Olig1 only (Bouvier et al., 2003). This evidence concerns the gene OLIG1 and oligodendroglioma.