IDH1 and oligodendroglioma: There were higher odds of expressing IDH1 mutation for younger patients (OR 5.48, 95% CI 3.17–9.47, in the ≤39 years group), those from an Asian/Asian British background (OR 3.68, 95% CI 1.05–12.97) or those with MGMT promoter methylation (OR 15.92, 95% CI 7.30–34.75) or an oligodendroglioma diagnosis (OR 7.45, 95% CI 2.90–19.13) and those receiving a gross total/total microscopic resection (OR 1.95, 95% CI 1.24–3.08).