Epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP) are subepithelial blistering diseases characterized by antibodies against different epithelial basement membrane zone antigens; specifically, EBA results from antibodies against type VII collagen (COL7), while BP arises from antibodies against BP antigen 180 (BP180, or COL17) or against BP230161. This evidence concerns the gene COL17A1 and acquired epidermolysis bullosa.