These observations resulted in the recognition of 2 autoimmune endotypes of CSU: 1) type I autoimmunity (also called autoallergy); derived by specific IgE autoantibodies against auto-antigens such as TPO, IL-24 and double strand DNA66 and; 2) type IIb autoimmunity characterized by the presence of IgG-specific autoantibodies, directed against IgE or α-subunit of FcεRI on mast cells and basophils, and originally assessed by the demonstration of positive ASST.10 The gene discussed is FCER1A; the disease is Autoimmunity.