XP is an autosomal recessive inherited disorder. This means you must have 2 copies of an abnormal gene in order for the disease or trait to develop. The disorder is inherited from both your mother and father at the same time. The abnormal gene is rare, so the chances of both parents having the gene are very rare. For this reason, it is unlikely for somebody with the condition to pass it on to the next generation, although it is possible.

UV light, such as from sunlight, damages the genetic material (DNA) in skin cells. Normally, the body repairs this damage. But in people with XP, the body does not fix the damage. As a result, the skin gets very thin and patches of varying color (splotchy pigmentation) appear.

Symptoms usually appear by the time a child is 2 years old.

Skin symptoms include:

• Sunburn that does not heal after just a little bit of sun exposure
• Blistering after just a little bit of sun exposure
• Spider-like blood vessels under the skin
• Patches of discolored skin that get worse, resembling severe aging
• Crusting of the skin
• Scaling of the skin
• Oozing raw skin surface
• Discomfort when being in bright light (photophobia)
• Skin cancer at a very young age (including melanoma, basal cell carcinoma, squamous cell carcinoma)

Eye symptoms include:

• Dry eye
• Clouding of the cornea
• Ulcers of the cornea
• Swelling or inflammation of the eyelids
• Cancer of eyelids, cornea or sclera

Nervous system (neurologic) symptoms, which develop in some children, include:

• Intellectual disability
• Delayed growth
• Loss of hearing
• Muscle weakness of the legs and arms

The health care provider will perform a physical exam, paying special attention to the skin and eyes. The provider will also ask about a family history of XP.

Tests that may be done include:

• Skin biopsy in which skin cells are studied in the laboratory
• DNA testing for the problem gene

The following tests can help diagnose the condition in a baby before birth:

• Amniocentesis
• Chorionic villus sampling
• Culture of amniotic cells

People with XP need total protection from sunlight. Even the light coming through windows or from fluorescent bulbs can be dangerous.

When out in the sun, protective clothing must be worn.

To protect the skin and eyes from the sunlight:

• Use sunscreen with the highest SPF you can find.
• Wear long-sleeve shirts and long pants.
• Wear sunglasses that block UVA and UVB rays. Teach your child to always wear sunglasses when outdoors.

To prevent skin cancer, your provider may prescribe medicines, such as a retinoid cream, to apply to the skin.

If skin cancer develops, surgery or other methods will be done to remove the cancer.

More information and support for people with XP and their families can be found at:

• National Organization for Rare Disorders – rarediseases.org/rare-diseases/xeroderma-pigmentosum/
• Xeroderma Pigmentosum Society – www.xps.org

Over one half of people with this condition die of skin cancer early in adulthood.

Contact your provider for an appointment if you or your child has symptoms of XP.

Experts recommend genetic counseling for people with a family history of XP who wish to have children.

Bender NR, Chiu YE. Photosensitivity. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 675.

Patterson JW. Disorders of epidermal maturation and keratinization. In: Patterson JW, ed. Weedon's Skin Pathology. 5th ed. Philadelphia, PA: Elsevier; 2021:chap 10.

Updated by: Ramin Fathi, MD, FAAD, Director, Phoenix Surgical Dermatology Group, Phoenix, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.