ELISA analysis using recombinant BP180 NC16A demonstrated that 22–100% of BP sera reacted to BP180 NC16A peptides and that autoantibodies targeting NC16A domain are associated with tense blisters, severe urticarial erythema, extensive lesions, and elevated eosinophils (45, 77). This evidence concerns the gene COL17A1 and Erythema.