How Common Is XP Disease?

Reviewed on 7/13/2021

XP (xeroderma pigmentosum) is an inherited disorder that makes a person extremely sensitive to the effects of ultraviolet radiation (UV) from the sun and other sources, putting them at very high risk for skin cancer and other medical problems. XP is very rare, affecting only one in one million people in the U.S.
XP (xeroderma pigmentosum) is an inherited disorder that makes a person extremely sensitive to the effects of ultraviolet radiation (UV) from the sun and other sources, putting them at very high risk for skin cancer and other medical problems. XP is very rare, affecting only one in one million people in the U.S.

XP (xeroderma pigmentosum) is a rare hereditary disorder characterized by extreme sensitivity to the DNA damaging effects of ultraviolet radiation (UV) from the sun and other sources, leading to a very high risk of skin cancer and other medical problems. 

Other than sunlight, sources of UV include:

  • Unshielded fluorescent light bulbs
  • Mercury vapor lights
  • Halogen light bulbs

XP is considered very rare, affecting an estimated one in one million people in the U.S. XP seems to be somewhat more common in Japan, North Africa, and the Middle East.

What Are Symptoms of XP Disease?

People who have XP (xeroderma pigmentosum) are very sensitive to the DNA damaging effects of ultraviolet radiation (UV) radiation from the sun and symptoms usually impact the skin, eyes, and nervous system.

  • Skin effects
    • About half of people with XP get blistering burns on sun-exposed skin after minimal sun exposure (sometimes less than 10 minutes in the sun)
    • Burns may be so severe that child abuse is suspected
    • The other half of XP patients tan after sun exposure and do not burn
    • Both types of sun reactions result in the early onset of freckling of the skin
    • Dry, parchment-like skin (xerosis
    • Both increased and decreased skin pigmentation (poikiloderma)
    • Thinning skin 
    • Spider veins” (telangiectasia)
    • Precancerous skin spots (actinic keratosis
    • Skin cancers 
  • Eye effects
    • Light sensitivity, or pain upon seeing light (photophobia) is common 
    • Inflammation of the whites of the eyes (conjunctiva) 
    • Dry eye
    • Feeling “something is in the eye”
    • Constant irritation
    • Eye redness 
    • May result in chronic eye inflammation and inflammation of the cornea (keratitis)
      • In severe cases, keratitis can result in lack of transparency (corneal opacification) and an increase in blood vessel density (vascularization) which may contribute to blindness
    • Eyelids may atrophy and eyelashes may fall out, leaving the eyes unprotected and contributing to vision loss with repeated sun exposure
    • Cancers of the eyelids, tissues surrounding the eyes, cornea, and white part of the eye (sclera) can occur early in life
  • Neurologic (nerve) effects
    • About 25% of XP patients develop a progressive neurodegeneration
      • Smaller head size and structural changes in the brain (acquired microcephaly)
      • Diminishing (or absent) deep tendon reflexes
      • Deafness caused by damage to the nerves of the inner ear
      • Progressive cognitive impairment
      • Developmental and learning disabilities
      • Muscle spasticity
      • Poor muscle control and coordination (ataxia)
      • Seizures
      • Difficulty swallowing and/or vocal cord paralysis
  • Cancer

What Causes XP Disease?

XP (xeroderma pigmentosum) is a genetic disorder passed from generation to generation in a family. Mutations in at least eight different genes are known to play a role in XP. 

How Is XP Disease Diagnosed?

XP (xeroderma pigmentosum) is usually diagnosed based on the presence of symptoms, such as signs of extreme sun sensitivity, including severe burning and blistering with only a small amount of sun exposure or even exposure to indoor fluorescent lights. 

Signs of XP can show up as early as infancy. Young children who have a large number of freckles on their face and other areas of the body that are frequently exposed to the sun may also be suspected of having XP. 

Genetic testing for mutations in XP genes is used to confirm the diagnosis.

What Is the Treatment for XP Disease?

Treatment for XP (xeroderma pigmentosum) involves preventing UV damage, skincare, eye care, and treatment for cancers that may develop.

  • Prevention
    • Ultraviolet (UV) sun protection
      • Protective clothing such as hats, hoods with UV blocking face shields, long sleeves, pants, and gloves
      • High sun-protective factor (SPF) sunscreens
      • UV-blocking glasses with side-shields
      • The patient’s surroundings (e.g., home, school, and work) should be tested for levels of UV using a UV light meter to identify areas of increased UV and sources of damaging UV so they can be eliminated from the environment
      • Windows in homes, schools, workplaces, and cars of XP patients should be treated with UV blocking film
    • Vitamin D supplementation
    • Don’t smoke and avoid secondhand smoke
  • Skin care
    • Skin examinations by a dermatologist at least every 6-12 months to detect precancerous and cancerous lesions and remove them
    • Patients and parents or caregivers of affected children should be taught skin examination techniques to help with early detection of possible skin cancers
    • Treatment of skin cancers 
  • Eye care
    • Routine eye exams with an ophthalmologist
    • Treatment of eye abnormalities
    • Lubricating eye drops 
    • Soft contact lenses to protect against trauma caused by deformed eyelids
    • Surgery for eye problems
  • Neurologic care
    • Basic neurologic examinations 
    • Childhood and special education classes
    • Physical and occupational therapies 
    • UV safe accommodations at school for XP children
    • Regular hearing exams 
    • Wheelchairs
    • Feeding tubes 
    • Long term nursing care

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Reviewed on 7/13/2021
References
https://www.cancer.net/cancer-types/xeroderma-pigmentosum#:~:text=XP%20is%20considered%20to%20be,Africa%2C%20and%20the%20Middle%20East.

https://rarediseases.org/rare-diseases/xeroderma-pigmentosum/