Xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare autosomal recessive disease characterised by photosensitivity, pigmentary changes, premature skin ageing, neoplasia and abnormal DNA repair.

This chapter is set out as follows:

• XP affects males and females equally
• The skin is normal at birth
• The first skin changes are noticed between the sixth month and third year in over 75% of cases, but may appear in later childhood
• Most cases beginning in childhood have reached the tumour stage by the age of 20 years, but it can arise as early as four years
• Photophobia and conjunctivitis are common features
• Neurological abnormalities occur in approximately 20% of cases

• Freckling and dryness on UV-exposed sites
• Acute sunburn or persistent erythema
• Actinic keratoses, SCC and BCC are all common and present in large numbers
• Melanomas arise and may be multiple

• The condition is usually diagnosed from a young age
• Testing the DNA repair factor from a blood or skin sample is conclusive

• Patients require a multidisciplinary team-approach - Guys and St Thomas NHS Foundation Trust run a highly specialised service for children and adults from all over the UK 

• Genetic counselling is also needed - parents who have a child with XP have a one in four chance of having another affected child

• Patient support group - the Xeroderma Pigmentosum Support Group