COL17A1 and autoimmune bullous skin disease: A major target of pemphigoid autoantibodies is the bullous pemphigoid antigen of 180 kDa (BP180), also referred to as collagen XVII, a hemidesmosomal transmembrane protein with a type II orientation whose extracellular domain consists of 15 collagenous regions interrupted by non-collagenous portions (Figure 1A) [1,4,6].