[1] Univ Leicester, Dept Genet & Med, Div Med Genet, Leicester LE1 7RH, Leics, England
[2] Univ Roma Tor Vergata, Div Human Genet, Rome, Italy
[3] Washington Univ, Sch Med, Dept Genet, St Louis, MO 63110 USA
[4] Univ Glasgow, Western Infirm, Dept Dermatol, Glasgow G11 6NT, Lanark, Scotland
[5] Kings Coll London, St Johns Inst Dermatol, London WC2R 2LS, England
[6] Washington Univ, Sch Med, Dept Pediat, St Louis, MO 63110 USA
[7] Washington Univ, Sch Med, Dept Med, Div Dermatol, St Louis, MO 63110 USA