Not all patients with XP have a history of severe and prolonged sunburn on minimal sun exposure. The normal sunburn response of patients with XP-C, XP-E and XP-V may relate to the preservation of transcription-coupled DNA repair in these groups. Those with a history of severe sunburn on minimal sun exposure developed their first skin cancer at an older age compared with patients with XP-C, XP-E and XP-V, but they had an increased frequency of neurological abnormalities. Physicians need to be aware that about half of all patients with XP will present without a history of abnormal sunburn.