OLIG2 and astrocytoma (excluding glioblastoma): Olig2 gene expression presents as bidirectional (up- and downregulation) changes in astrocytoma cases (n = 105), but there is no statistical significance in survival outcome among Olig2 gene upregulated (n = 62), intermediate level (n = 33), and downregulated (n = 10) subgroups (p > 0.05) (data not shown).