What is XP?
Xeroderma Pigmentosum (or XP) is a rare inherited disease affecting both males and females. It causes a person to be extremely sensitive to the damaging effects of ultraviolet radiation. Undiagnosed and untreated, XP can lead to the early onset of skin cancer and blindness. In addition, approximately 20% of the people with XP develop progressive neurological disease.
HOW IS XP DIAGNOSED?
Often the first people to suspect that, something is “wrong” are the parents. Many parents notice that in early infancy around 1-2 years of age their children will have unusually dark freckles (lentigos) or will have had severe sunburns after only being in the sun a few minutes.
A thorough skin exam by a dermatologist, along with a small skin biopsy for laboratory testing, is the standard method for diagnosing XP. Xeroderma Pigmentosum can usually be conclusively diagnosed by measuring the DNA repair function from the skin cells obtained from the biopsy.
Symptoms of XP
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Early onset of freckling, (before age 2) especially in sun exposed areas of the skin, severe burns after only a short duration of sun exposure or exposure to ultraviolet lights. Some people with XP may develop burns even in shady areas.
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Blistering or freckling after minimal sun or ultraviolet exposure
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A dry, premature-aged appearance to the skin and lips
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Photosensitivity of the eyes (become red and sore when exposed to the sunlight)
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Early onset of skin cancer in any skin, including the tip of the tongue
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Progressive Neurological Complications
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Developmental disabilities
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High frequency hearing loss, progressing to deafness
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Loss of previously attained abilities such as walking and talking
XP is an autosomal recessive disease caused by mutations in genes that are critical for DNA repair. The body must repair DNA when it is damaged by harmful external agents such as ultraviolet radiation and chemicals.
XP is caused by a mutation in one of the eight critical DNA repair genes: XP-A, XP-B, XP-C, XP-D, XP-E, XP-G, and XP-variant. The specific genotype of XP an individual has depends on the repair gene that is affected.
Before the specific XP genes were discovered, researchers used the term “complementation group” to classify gene variations. Cells were grouped based on their ability to repair UV-damaged DNA. Mutations in the A, C, D, and variant genes account for about 90% of XP cases.
WHAT IS THE TREATMENT FOR XP?
There is currently no cure for XP. Patients with XP and their families will face many challenges in daily living. Constant educating and reminding of the need to protect oneself from sunlight is paramount to the management of Xeroderma Pigmentosum.
The main treatment for XP is protection from UV exposure to prevent its harmful effects on the skin.
Many patients with XP die at an early age due to skin cancers. However, with early diagnosis, no neurological symptoms (or mild variant), and strict adherence to UV light, patients may live beyond middle age.
WHAT IS UV?
Ultraviolet UV light lies between visible light and X-rays on the light spectrum. It is invisible to the human eye because our eyes cannot detect shorter wavelengths. For individuals with XP, UV exposure must be avoided. However, sunlight’s color and warmth when properly filtered can be low risk. The challenge is to effectively filter or eliminate to make a safe environment for someone with XP.