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Xeroderma Pigmentosum

Inherited Disease Causes Extreme Sun Sensitivity

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Updated June 10, 2014

Xerosis is excessively dry skin

Xerosis is excesssively dry, scaly skin

Photo (c) A.D.A.M.
Xeroderma pigmentosum (XP) is an inherited disease that causes extreme sensitivity to ultraviolet (UV) light. UV light damages the genetic material (DNA) in cells and disrupts normal cell function. Normally, damaged DNA is repaired by the body, but the DNA repair systems of people with XP do not function properly. In XP, the damaged DNA builds up and becomes harmful to the body’s cells, particularly in the skin and eyes.

Xeroderma pigmentosum is inherited in an autosomal recessive pattern. It affects both men and women of all ethnic backgrounds. XP is estimated to occur in 1 in 1,000,000 individuals in the United States. In some areas of the world, such as North Africa (Tunisia, Algeria, Morocco, Libya, Egypt), the Middle East (Turkey, Israel, Syria), and Japan, XP occurs more often.

Skin Symptoms

People with xeroderma pigmentosum experience skin symptoms and changes from being in the sun. These may include:
  • unusually severe sunburn that may include blistering after only being in the sun a short time
  • sunburn lasts much longer than expected, sometimes for several weeks
  • development of lots of freckles at an early age
  • excessively dry skin (xerosis)
  • rough-surfaced skin growths (solar keratoses)
  • irregular dark spots
  • development of any of the three common types of skin cancer: basal cell carcinoma, squamous cell carcinoma, or melanoma
The name “xeroderma pigmentosum” means “dry pigmented skin.” Exposure to the sun over time causes the skin to become darker, dry, and parchment-like. Even in children the skin looks like the skin of farmers and sailors who have been in the sun for many years.

People with xeroderma pigmentosum who are younger than 20 years old have more than 1,000 times the risk of developing skin cancer than people without the disease. The first skin cancer may develop before a child with XP is 10 years old, and many more skin cancers may develop in the future. In XP, skin cancer develops most often on the face, the lips, on the eyes, and on the tip of the tongue.

Eye Symptoms

People with xeroderma pigmentosum also experience eye symptoms and changes from being in the sun. These may include:
  • eyes are painfully sensitive to the sun
  • eyes are easily irritated and become bloodshot
  • ectropion, a turning out of the edge of the eyelid
  • inflammation (keratitis) of the cornea, the clear part of the front of the eye that lets light through
  • cloudiness of the cornea
  • darkening of the skin of the eyelids; sometimes the eyelashes fall out

Nervous System Symptoms

About 20-30% of people with xeroderma pigmentosum also have nervous system symptoms such as:
  • hearing loss that gets worse over time
  • poor coordination
  • spastic muscles
  • a smaller-than-normal head (called microcephaly)
  • intellectual impairment that gets worse over time
  • seizures
Nervous system symptoms may be present in infancy, or they may not appear until late childhood or adolescence. Some people with XP will only develop mild nervous system symptoms at first, but the symptoms tend to become worse over time.

Diagnosis

The diagnosis of xeroderma pigmentosum is based on the skin, eye, and nervous system symptoms (if present). A special test performed on blood or a skin sample can look for the DNA repair defect present in XP. Tests may be done to rule out other disorders that can cause similar symptoms, such as Cockayne syndrome, trichothiodystrophy, Rothmund-Thomson syndrome, or Hartnup disease.

Treatment

There is no cure for xeroderma pigmentosum, so treatment focuses on any problems that are present and preventing future problems from developing. Any cancers or suspicious lesions should be treated or removed by a skin specialist (dermatologist). An eye specialist (ophthalmologist) can treat any eye problems that occur.

Since it is the UV light that causes damage, a big part of prevention of problems is protecting the skin and eyes from sunlight. If someone with XP has to go outside during the day, he or she should wear long sleeves, long pants, gloves, a hat, sunglasses with side shields, and sunscreen. When indoors or in a car, the windows should be closed to block the UV rays from sunlight (although UVA light can still penetrate, so a person must be fully clothed). Children with XP should not play outdoors during the daytime.

Some types of indoor light (such as halogen lamps) can also give off UV light. Indoor sources of UV light in the home, school, or work environment should be identified and eliminated, if possible. People with XP can also wear sunscreen indoors to protect against unrecognized sources of UV light.

Other important parts of preventing problems are frequent skin examinations, eye examinations, and early testing and treatment for nervous system problems such as hearing loss.

Sources:

"Understanding Xeroderma Pigmentosum." Patient Information Publications. 2006. Clinical Center, National Institutes of Health. 24 Oct 2008

Kraemer, Kenneth. "Xeroderma Pigmentosum." GeneReviews. 22 Apr 2008. GeneTests. 25 Oct 2008

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