Moreover, several underlying mechanisms sustaining CSU have been suggested: from an autoimmune hypothesis (IgG antibodies against the FcεRI alpha subunit of the high-affinity IgE receptor have been found in more than one-third of CSU patients [18], while 5–10% exhibit the production of IgG against IgE antibodies [19]; moreover, up to 33% of CSU patients have anti-thyroid autoantibodies [20]) to an activation of the extrinsic coagulation pathway [21, 22] or even a possible class E immunoglobulin- (IgE-) mediated autoimmunity [23]. Here, FCER1A is linked to Autoimmunity.