The BoNT/A toxin, BTXA (Hengli, Lanzhou Institute of Biological Products, China), elicited an acute hypersensitive reaction of erythema in a site other than the injected area [36] in three patients. Erythema is a consequence of Type I hypersensitivity involving IgE, leading to mast cell degranulation with the production of inflammatory mediators such as histamine [16]. The gene discussed is IGHE; the disease is Erythema.