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What is xeroderma pigmentosum?

Katie Mahar suffers from XP and can't risk exposure to the sun. Her parents founded Camp Sundown.
Katie Mahar suffers from XP and can't risk exposure to the sun. Her parents founded Camp Sundown.
AP Photo/Jim McKnight

There are people who must spend their lives in the dark or risk terrible injuries and diseases. They avoid sunlight. Their windows are covered with protective film, blinds and curtains. They only venture outdoors at night. Even walking into a room lit by fluorescent bulbs can be risky. They suffer from a rare condition called xeroderma pigmentosum (XP). In the United States, the frequency of cases is about one in every 250,000 people [source: Diwan].

This genetic condition affects a person's ability to recover from ultraviolet radiation. Upon exposure to ultraviolet rays, a person with XP will experience severe damage almost instantly. The person's skin will begin to blister mere moments after exposure. These injuries can lead to even more serious consequences.

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A pair of physicians named Moriz Kaposi and Ferdinand von Hebra first identified the disease in 1874. Kaprosi named the disease in 1882. The term xeroderma pigmentosum refers to the appearance and texture of affected skin -- it's leathery and has increased pigmentation.

Much later, physicians discovered that the disease was caused by a genetic disorder. The genes that carry XP are recessive -- both the mother and father must carry the gene to produce a child with XP. Because the genes are recessive, it's possible for a person to be a carrier without suffering from the symptoms of XP him- or herself.

The condition has three stages. The first stage begins around six months after birth. Up to that point, the child's skin typically appears to be normal and healthy. But around six months of age, children with XP tend to develop freckles and scaly skin upon exposure to the sun. The second stage includes more extensive damage and noticeable symptoms -- the skin might become rubbery or leathery upon exposure to ultraviolet radiation. The third stage involves the development of skin cancer.

While the skin's sensitivity to ultraviolet radiation is the most common symptom of XP, some children with the disease suffer other problems. Around 20 percent of children with XP also suffer neurological damage. Developmental disorders aren't uncommon and some children may lose the ability to speak, walk or perform other tasks.

 

Unfortunately, options for treatment of XP are few and far between. There is no known cure for the condition. The genetic nature of the disease affects the body's ability to repair DNA damaged by ultraviolet radiation. Until there's a breakthrough in genetic treatments, a person with XP has few options other than to limit exposure to ultraviolet radiation as much as possible.

Many people who suffer XP must seek out cancer treatments later on in life. Some endure multiple surgical procedures to remove cancerous growths from their skin and eyes. Diagnosis of the condition early is paramount to limiting damage as much as possible. Since even brief exposure can lead to blisters and skin cancer, discovering the condition before the child has experienced too much UV exposure is critical.

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Those affected by XP must try to avoid ultraviolet radiation in all its forms. Parents with children who have XP will need to keep the children indoors during daylight hours. Untreated windows may let in ultraviolet radiation and must be covered, too. Some parents go a step further and will apply sunscreen to children multiple times a day while minimizing the chance for sunlight to get inside. Children with XP develop skin cancers at a rate 1,000 times higher than the average population [source: Diwan].

Parents will also need to monitor the lighting conditions of their homes as well as any destination the child may visit. Incandescent bulbs don't emit much ultraviolet radiation. Fluorescent bulbs can emit more. If the radiation is intense enough, someone suffering from XP could experience symptoms upon exposure.

Regular visits to a dermatologist are important. People with XP must have their skin checked for signs of growths every three to six months. Because so many people with XP also develop eye problems, regular visits to an ophthalmologist are a good idea too. Neurological examinations may also be necessary.

Living with XP can be an isolating and frustrating experience. Parents have little hope of providing their kids with a typical childhood. Normal schools and activities simply aren't an option. Yet through extraordinary efforts, parents can provide children with XP the education and social activities they need.

While we have no cure for XP yet, doctors, scientists and support groups are determined to continue research into the condition to find ways to treat and defeat the disease. In the meantime, people with XP will have to continue to avoid sunlight and other forms of ultraviolet radiation.

For more on XP and other skin conditions, take a look at the links on the next page.

Related HowStuffWorks Articles

Sources

  • Diwan, A. Hafeez. "Xeroderma Pigmentosum." Emedicine. Oct. 7, 2008. (May 27, 2010) http://emedicine.medscape.com/article/1119902-overview
  • Foderaro, Lisa W. "Hudson Journal; Where Daylight's a Risk, Dark Is a Time to Shine." The New York Times. July 21, 2002. (May 27, 2010) http://www.nytimes.com/2002/07/21/nyregion/hudson-journal-where-daylight-s-a-risk-dark-is-a-time-to-shine.html
  • Kraemer, Kenneth H. "Xeroderma Pigmentosum." GeneReviews. April 22, 2008. (May 27, 2010) http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=xp
  • Miller, Samantha. "Into the Night." People Magazine. Vol. 50, No. 6. Aug. 24, 1998. (May 27, 2010) http://www.people.com/people/archive/article/0,,20126080,00.html
  • Ngan, Vanessa. "Xeroderma pigmentosum." DermNet NZ. June 15, 2009. (May 27, 2010) http://dermnetnz.org/systemic/xeroderma-pigmentosum.html
  • The Xeroderma Pigmentosum Society. (May 27, 2010) http://www.xps.org/
  • Williams, Monte. "A Family Turns Night Into Day for a Child With a Rare Skin Disease." The New York Times. May 14, 1997. (May 27, 2010)http://www.nytimes.com/1997/05/14/nyregion/a-family-turns-night-into-day-for-a-child-with-a-rare-skin-disease.html

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