AIBDs are characterized by the presence of well-characterized circulating and tissue-bound pathogenic autoantibodies directed against multiple skin structural proteins present in desmosomes (e.g., pemphigus vulgaris, PV), hemidesmosomes (e.g., bullous pemphigoid, BP, and epidermolysis bullosa acquisita, EBA) or against epidermal/tissue transglutaminase (eTG/tTG) present in dermatitis herpetiformis (DH), the cutaneous manifestation of celiac disease (CD) (27, 28). This evidence concerns the gene TGM2 and acquired polycythemia vera.