In contrast to BP, neither aberrant levels of circulating Hsp90 nor any correlation of this protein with serum anti-desmoglein autoantibodies or clinical status was found in a control cohort of patients with pemphigus vulgaris, a different autoimmune blistering disease characterized by an autoimmune response against desmosomal structures of the skin. This evidence concerns the gene HSP90AA1 and pemphigus vulgaris.