1. UK National Xeroderma Pigmentosum Service; Department of Photodermatology; St John's Institute of Dermatology; Guy's and St Thomas' NHS Trust London U.K
2. Genome Damage and Stability Centre; University of Sussex; Brighton U.K
3. Istituto di Genetica Molecolare CNR; Pavia 27100 Italy
4. Department of Cell Biology and Genetics; Erasmus Medical Center; Rotterdam the Netherlands
5. Department of Dermatopathology; St John's Institute of Dermatology; Guy's and St Thomas' NHS Trust London U.K