IDH1 and glioblastoma: There was an overall preponderance of males (P < 0.0001), with modulation by specific diagnosis: more males were diagnosed with glioblastoma, IDH-wildtype [odds ratio 1.20, 95% confidence interval (CI) 1.067 to 1.35, P = 0.002], but fewer with oligodendroglioma, IDH-mutant and 1p/19q-codeleted relative to the overall gender imbalance (odds ratio 0.85, 95% CI 0.73 to 0.98, P = 0.03).