In one report, low Olig1 expression was detected along with a marked upregulation of Olig2 (Riemenschneider et al., 2004), while another study found an upregulation of both Olig1 and Olig2, although the sample size was small (4 cases of diffuse astrocytomas; Aguirre-Cruz et al., 2004). The gene discussed is OLIG2; the disease is diffuse astrocytoma.