The secretion of preformed mediators (e.g. histamine) and de novo synthesis of lipid mediators (e.g. leukotriene C4, prostaglandin D2) and various cytokines following FcεRI cross-linkage plays key roles in diverse IgE-mediated allergic conditions, including atopic dermatitis (AD) (23), chronic spontaneous urticaria (CSU) (24, 25), asthma (5, 26, 27), allergic rhinitis (28), food allergies (29), and anaphylaxis (30–32). This evidence concerns the gene IGHE and Alzheimer disease.