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Xeroderma Pigmentosum (XP)

Name of disease:

Xeroderma Pigmentosum (XP)

ICD-10 diagnosis code:

Q82.1

Causes:

  • XP is caused by mutations in at least nine genes: DDB2, ERCC1, ERCC2, ERCC3, ERCC4, ERCC5, POLH, XPA, and XPC. These genes are involved in repairing damaged DNA.
  • DNA can be damaged by UVR and by toxic chemicals such as those found in cigarette smoke. Normal cells are usually able to fix DNA damage before it causes problems. However, in people with xeroderma pigmentosum, DNA damage is not repaired normally.
  • As damage builds up in DNA, cells malfunction and eventually become cancerous or die.

Mode of inheritance:

XP is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell must have variants to cause the disorder.
The parents of an individual with an autosomal recessive condition each carry one of the altered genes, but they typically do not show signs and symptoms of the condition.

Prevalence:

It is estimated that XP affects about 1 in 1 million people in the US and Europe. The condition is more common in Japan, North Africa, and the Middle East.

Diagnosis:

  • Skin biopsy
  • Genetic blood test

Age of onset:

  • Signs of XP usually appear in infancy or early childhood.
  • About half of affected children develop a severe sunburn after spending just a few minutes in the sun.

Common signs and symptoms:

  • Burning easily in the sun no matter the colour of your skin
  • Freckles from an early age (under 2 years) in areas exposed to daylight
  • Eye sensitivity to bright light (photophobia)
  • Eye surface cancers
  • Skin cancers
  • Skin ageing
  • Nerve or brain (neurological) problems such as hearing loss, poor balance, poor memory, or learning problems
  • People with XP are 10,000 times more likely to develop non-melanoma skin cancer and up to 2,000 times more likely to develop melanoma skin cancer compared to individuals without this condition.
  • Most commonly, the first skin cancer appears in affected individuals before age 10.

Available treatment (medicinal and non-medicinal):

  • There is no cure for XP.
  • It is important to keep skin damage to a minimum.
  • Most people with XP have a low vitamin D level because they need to protect their skin from daylight. Doctors may advise them to take vitamin D supplements if the vitamin D level is low.

Disease management tips:

  • Stay away from all sources of ultraviolet radiation (UVR) wherever possible unless you are protected with suitable clothes or sunscreen.
  • The risk of UVR exposure is higher in the summer and in the middle of the day. Try to plan the day to avoid being exposed to UVR as much as possible.
  • Choose protective clothes, for example, hats or caps that shade your head, face, and neck as much as possible, full-face visors or wrap-around sunglasses, long-sleeved tops, gloves, and full-length trousers.
  • Put on sunscreen 20 to 30 minutes before exposure to any UVR. After this, apply sunscreen again every 2 to 3 hours.
  • Install UVR protective film on windows.
  • Close curtains or blinds on unprotected windows to reduce UVR levels.
  • Some light bulbs produce UVR. The further away you are from the bulb, the lower the risk.

References:

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