IGHE and seasonal allergic rhinitis: For binary risk factors the results can be interpreted by risk of disease/odds ratio for glioma per 2.7-fold increase in odds of the risk factor (exposure). No strong evidence of any association between glioma and asthma and hay fever (OR 0.96; 95% CI: 0.90–1.03. P = 0.248), IgE levels (OR 0.88; 0.69–1.13. P = 0.319), or self-reported allergy (OR 1.03; 95% CI: 0.95–1.11. P = 0.534). For atopic dermatitis an inverse association was found by IVW (OR 0.96; 95% CI: 0.93–1.00. P = 0.041) and MLE (OR 0.96; 95% CI: 0.94–0.99. P = 0.003)