Based on the prevalence of pemphigus and pemphigoid antibodies in healthy individuals and the prevalence of AIBD, every 25th individual with autoantibodies against pemphigus antigens is likely to develop pemphigus; similarly, every 37th healthy individual with anti-BP180-NC16A IgG reactivity would be expected to develop BP. This evidence concerns the gene COL17A1 and pemphigus.