Furthermore, factors consistent with the hypothesis of fatal anaphylaxis include an immediately preceding challenge with an allergen known to cause reactions, clinical features consistent with or suggesting anaphylaxis, a previous history of reactions to similar or cross-reactive allergens, specific IgE antibodies to the allergen suspected of causing the reaction as well as measurable products of mast cell activation (26,43-45). The gene discussed is IGHE; the disease is anaphylaxis.