1 Department of Dermatology, Watford General Hospital, Hertfordshire Hospitals NHS Trust, Watford, Hertfordshire, UK.
2 Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
3 Manchester Centre for Genomic Medicine, Genetic Medicine, St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK.