Among individuals with convincing IgE-mediated sesame allergy, an estimated 23.6% (95% CI, 16.9%-32.0%) to 37.2% (95% CI, 29.2%-45.9%) had previously experienced a severe sesame-allergic reaction, depending on the definition used, and 81.6% (95% CI, 71.0%-88.9%) of patients with convincing sesame allergy had at least 1 additional convincing food allergy. The gene discussed is IGHE; the disease is allergic disease.