M Charalambides1, C Flohr2, P Bahadoran3,4, R N Matin5. 1. College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK. 2. Unit for Population-Based Dermatology Research, St John's Institute of Dermatology, King's College London and Guy's & St Thomas' NHS Foundation Trust, London, UK. 3. Department of Dermatology, Université Côte d'Azur, Centre Hospitalier Universitaire Nice, Nice, France. 4. Université Côte d'Azur, Inserm U1065, Team 1, C3M, Nice, France. 5. Department of Dermatology, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.