In IgE-mediated anaphylaxis, allergen cross-linking of specific IgE bound to the surface of mast cells and basophils initiates degranulation and release of mediators that cause urticaria, angioedema, bronchospasm, nausea, vomiting, diarrhea, hypotension, and/or shock (2). The gene discussed is IGHE; the disease is angioedema.