1. National Xeroderma Pigmentosum Service; Department of Photodermatology; St John's Institute of Dermatology; Guy's and St Thomas' NHS Foundation Trust; London SE1 7EH U.K.
2. Department of Ophthalmology; Guy's and St Thomas' NHS Foundation Trust; London SE1 7EH U.K.
3. Medical Physics Department; Guy's and St Thomas' NHS Foundation Trust; London SE1 7EH U.K.