COL17A1 and bullous pemphigoid: Bullous pemphigoid (BP), the most common skin autoimmune subepidermal blistering disease, often occurs in the elderly, and typically manifests as tense bullae on edematous erythema, accompanied by severe itching.1, 2 BP autoantibodies mainly target two hemidesmosomal components, BP180 and BP230, and anti-BP180 autoantibodies have been recognized as the major pathogenic autoantibodies in BP.1