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Xeroderma Pigmentosum
Tuesday, 12 July 2005
Tuesday, 12 July 2005
DeSanctis-Cacchione Syndrome

What

Xeroderma Pigmentosum (XP) is a genetic disorder characterized by extreme sensitivity to the sun leading to skin and eye problems including cancer. XP may also result in problems of the nervous system, as described further below.

Who

In the United States, the prevalence of XP is about 1 in 250,000 to 1 in 1 million people. This varies among different ethnicities. It is more common in Japan, North Africa (Tunisia, Algeria, Morocco, Libya, and Egypt), and the Middle East (Turkey, Israel, and Syria). XP equally affects both males and females.

Signs and Symptoms

The most distinguishable features of XP are the skin changes that start between 1 and 2 years of age. The skin is very sensitive to sunlight and half of individuals get sunburned even if they have only been in the sun for a short time. Sun exposure leads to freckles, and dry, tanned skin. Individuals can develop skin cancers at an early age. The most common types of tumors are squamous cell carcinoma, basal cell carcinoma, and malignant melanoma. The eyes are also damaged by the sun and symptoms start on average by 4 years of age. Children may be sensitive to looking at bright light (photophobia). The eyes may be red. The corneas (clear surfaces of the eye) may become cloudy. The eyelids get more tanned and may turn inward or outward. There may be loss of eyelashes or eyelids. About 30% of individuals develop problems with their nervous system. They may have a small head, hearing loss, jerky and uncoordinated movements, dementia, or mental retardation. Some may have slow genital growth or may not go through puberty until later. Rare, severe cases of XP, also known as DeSanctis-Cacchione syndrome, have very severe problems of the nervous system, are very short, and do not sexually mature normally. In children less than 20 years of age, there is a 1000-fold greater risk of skin and eye cancer with XP. If the sun is not avoided aggressively, cancer often occurs by 10 years of age.

Possible Causes

Xeroderma pigmentosum is inherited in an autosomal recessive manner. There are several genes that have been found to cause XP. These genes are responsible for repairing our cell’s DNA after it is damaged. Sunlight and other sources of ultraviolet (UV) light cause damage to our DNA. In children with XP, the body cannot repair the damage that is caused by the sun.

Diagnosis

The diagnosis of XP is made by having the above signs and symptoms that affect the skin and eye. Not all individuals have symptoms that affect the nervous system. Currently, genetic testing is not needed to confirm the diagnosis and is only available for research purposes.

Treatment

There is no cure for XP but research is ongoing. The most important treatment is avoidance of ultraviolet (UV) light by wearing protective clothing, UV-absorbing sunglasses, and high SPF sunblock every day. Long hairstyles also help to protect the skin. Special meters can measure the amount of UV light at home and at school because some lamps, such as halogens, can have high amounts of UV light. A family member should check the child’s skin frequently to catch skin cancers early. The child’s doctor should also monitor for cancers every 3 to 6 months. If anything develops, it should be removed to prevent it from spreading or getting worse. If the corneas of the eyes become affected, corneal transplant can be performed. If there are any eye cancers, these should be removed with eye surgery. Individuals with XP are also sensitive to cigarette smoke and this should be avoided.

Prognosis

The prognosis for XP varies from child to child depending on the severity of their symptoms. The risk of skin cancer is 1000 times higher than normal and there is a 50% chance of cancer by age 14. Individuals who have their nervous system affected may eventually need a wheelchair or have difficulty being out of bed. This can lead to life-threatening infections, especially respiratory (lung) infections. It is estimated that one third of patients succumb to cancer and another 11% to infections. 90% of patients with XP reach 13 years of age, 80% reach age 28 years of age, and 70% reach 40 years of age. With early diagnosis and diligence in avoiding UV light, patients have the potential for living longer.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

Xeroderma Pigmentosum Society
Great information for parents concerning research efforts and ways the family can connect with other families across the country for support and advice.

Birth Disorder Information Directory
List of several links to find out more about Xeroderma Pigmentosum.

Google Search for Xeroderma Pigmentosum

References and Sources

Gene Reviews: Xeroderma Pigmentosum. www.geneclinics.org/servlet/access?db=geneclinics&site=gt&id=8888891&key=ob6N3s-dsTo6c&gry=&fcn=y&fw=sbgm&filename=/profiles/xp/index.html OMIM: Xeroderma Pigmentosum. McKusick V. www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=278700 www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=278720 www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=278730 EMedicine: “Xeroderma Pigmentosum” Peter Hedera MD. Last update March 1, 2005.