[1] Univ Calif San Francisco, Dept Dermatol, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Dept Pathol, San Francisco, CA 94143 USA
[3] Kings Coll London, St Johns Inst Dermatol, Cutaneous Med Unit, London WC2R 2LS, England
[4] Univ Munster, Dept Dermatol, D-48149 Munster, Germany
[5] Univ Manchester, Ctr Dermatol Res, Manchester M13 9PL, Lancs, England
[6] NIHR Manchester Biomed Res Ctr, Manchester M13 9PL, Lancs, England
[7] Univ Penn, Perelman Sch Med, Dept Dermatol, Philadelphia, PA 19104 USA