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Chromosomes and DNA
Chromosomes and DNA

Xeroderma pigmentosa
Definition:
Xeroderma pigmentosa is an inherited inability to repair DNA damage from ultraviolet light.

Causes, incidence, and risk factors:

Xeroderma pigmentosa is inherited as an autosomal recessive trait. Those affected are extremely sensitive to the ultraviolet portion of sunlight. Ultraviolet light exposure damages DNA (the genetic material within a cell) in skin cells.

Normally, peoples' bodies can repair this damage. However, people with xeroderma pigmentosa cannot repair the damaged DNA and rapidly develop skin atrophy (thinning), splotchy pigmentation, spidery blood vessels in the skin (telangiectasia), and skin cancers.

Skin cancers include basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Basal cell skin cancers are fairly easy to treat and have a low rate of metastasis. Squamous cell cancer is more difficult to treat, and melanoma has a very high rate of spreading to other organs.

Affected people develop increasing disfigurement following any intermittent exposure to sunlight. Malignant (cancerous) skin lesions are often present before the child is 5 years old.
Symptoms:
  • A sunburn which does not heal following minimal sun exposure
  • Blistering following minimal sun exposure
  • Cutaneous telangiectasia
  • Increasing irregular pigmentation of the skin
  • Crusting of the skin
  • Scaling of the skin
  • Oozing raw skin surface
  • Discomfort when exposed to bright light (photophobia)
  • Neurologic changes are sometimes noted
Signs and tests:
There may be a family history of xeroderma pigmentosa.

Examination of the eyes may show other signs of this disorder: Tests:
Prenatal (before birth) diagnosis:
  • Amniocentesis
  • Chorionic villous sampling
  • Culture of amniotic cells
Postnatal diagnosis (after birth of the child):
Treatment:

Children with this condition require total protection from sunlight. In addition, light coming through window glass and light from fluorescent bulbs is also dangerous. When some sunlight exposure cannot be avoided, protective clothing should cover the skin.

High protection (SPF 30 or greater) sunscreen and very dark, UV-protected glasses should be worn. Trials of medications to help prevent skin cancers are currently being performed.
Support Groups:
Visit http://www.xps.orgwww.xps.org for more information and support.
Expectations (prognosis):
Most affected people die of malignancy early in adulthood.
Complications:
Calling your health care provider:
Call for an appointment with your health care provider if you or your child has symptoms of xeroderma pigmentosa.

Call for an appointment with your health care provider if you have a family history of xeroderma pigmentosa and you are planning to have children. Ask the provider about genetic counseling.
Prevention:
Genetic counseling is recommended for prospective parents with a family history of xeroderma pigmentosa. Intrauterine diagnosis is possible from cultured amniotic cells that exhibit the inability to repair DNA.
Review Date: 11/4/2001
Reviewed By: Michael Lehrer, M.D., Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
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