[1] Royal Victoria Infirm, Dept Dermatol, Newcastle Upon Tyne NE1 4LP, Tyne & Wear, England
[2] Univ Dundee, Ninewells Hosp & Med Sch, Epithelial Genet Grp, Human Genet Unit, Dundee DD1 9SY, Scotland
[3] Newcastle Univ, Sch Clin Med Sci Child Hlth, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[4] Kings Coll London, Dept Med & Mol Genet, London WC2R 2LS, England
[5] Kings Coll London, St Johns Inst Dermatol, London WC2R 2LS, England
[6] Newcastle Univ, Inst Human Genet, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England
[7] Newcastle Univ, Inst Cellular Med, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England