Xeroderma Pigmentosum

From WikiGenetics

1 Name of Condition
2 Definition
3 Description, Signs and Symptoms
4 Inheritance
5 Demographics
6 Diagnosis
7 Treatment and Management
8 Prognosis
9 Resources
10 References

[edit] Name of Condition

[edit] Definition

This extremely rare genetic condition is caused by a failure of the genes to repair DNA damage caused by UV exposure or other carcinogens such as cigarette smoke. The condition results in UV sensitivity and an extremely elevated risk of cancer.

[edit] Description, Signs and Symptoms

Xeroderma Pigmentosum causes extreme sensitivity to sunlight, which is characterized by blistering or freckling of the skin on minimum sun exposure, or premature aging of skin, lips, eyes, mouth and tongue with significant increased incidence of cancer in these same areas. Blindness may occur from eye lesions or surgery for skin cancer close to the eyes. In some cases, there may be progressive neurological complications including developmental disabilities, mental retardation, or high frequency hearing loss progressing to deafness.

[edit] Inheritance

Xeroderma pigmentosum is an autosomal recessive disorder, and is known to be associated with mutations in XPA, ERCC3 (XPB), XPC, ERCC2 (XPD), DDB2 (XPE), ERCC4 (XPF), ERCC5 (XPG), ERCC1, and POLH (XP-V). Mutations in XPA and XPC account for approximately 50% of XP. Molecular genetic testing of the XPA and XPC genes is clinically available. Molecular genetic testing for the remaining genes is available on a research basis only.

[edit] Demographics

This condition is extremely rare, with prevalence estimated at only about 1:1,000,000 in the United States. Some populations have a high frequency, such as in Japan, the prevalence is estimated as 1:40,000. Prevalence is increased in North Africa (Tunisia, Algeria, Morocco, Libya, and Egypt) and the Middle East (Turkey, Israel, and Syria), especially in communities in which consanguinity is common.

[edit] Diagnosis

The diagnosis of XP is made based on skin, eye, and neurologic manifestations. Clinical history and findings on examination of the skin and eyes are often not sufficient to make the diagnosis, so a detailed family history with attention to consanguinity may aid in diagnosis. Functional tests on living cells can be used to screen for abnormalities in DNA repair.

[edit] Treatment and Management

Prevention is the best treatment once the condition has been diagnosed. Avoid the sun and using protective clothing and sunscreen, sunglasses, and long hair styles. Vitamin D should be taken as a diet supplement due to the lack of sun exposure. Frequent skin examinations by a physician are recommended to watch for precancerous lesions.

[edit] Prognosis

Xeroderma Pigmentosum is a life-threatening condition because every exposure to sun can cause irreparable and additive DNA damage, putting individuals at extremely high risk for cancer, especially causing tumors on the skin, mouth, and eye. With proper, attentive care and treatment, individuals with this condition may live for many years.