MGMT and oligodendroglioma: Being 39 years and younger (OR 5.48, 95% CI 3.17–9.47), from Asian/Asian British background (OR 3.68, 95% CI 1.05–12.97), having MGMT methylation (OR 15.92, 95% CI 7.30–34.75), an oligodendroglioma diagnosis (OR 7.45, 95% CI 2.90–19.13) and receiving a gross total/total microscopic resection (OR 1.95, 95% CI 1.24–3.08) were each univariately correlated with IDH1 mutation.