What Is Xeroderma Pigmentosum

Xeroderma pigmentosum (XP) is a rare genetic condition affecting DNA repair. People with xeroderma pigmentosum are extremely sensitive to ultraviolet (UV) rays like those from the sun.

XP can affect not only the skin, which is extremely prone to sunburn, but also the eyes and sometimes the nervous system. This article will discuss the symptoms, causes, diagnosis, and treatment of xeroderma pigmentosum.

Xeroderma Pigmentosum Symptoms

From a very young age, people with XP experience serious damage from even minor sun exposure. Even as babies, some people with XP may blister and burn after just a few minutes in the sun—a burn that may take a week or more to heal.

Others with the condition are able to spend some time in the sun, but they have other skin issues, such as freckling and developing dry parchment-like skin.

Common skin symptoms occurring in people with XP include:

• Skin becomes discolored and begins to thin.
• Broken blood vessels appear near the skin's surface.
• Very dark and light patches begin to appear on the skin.
• As early as 4 or 5 years of age, children may begin to develop skin cancer.

As many as 80% of XP patients also have eye problems. These problems may include:

• Painful sensitivity to sunlight
• Dry eyes
• Red, irritated eyes with chronic irritation of the cornea (the clear outer layer): With time this may cause the cornea to become cloudy and new blood vessels to grow. In some cases, this may eventually result in blindness.

About 25% of patients may also develop neurological signs, possibly from a loss of nerve cells in the brain. These symptoms may involve progressive hearing loss, muscle tightness, lower tendon reflexes, seizures, intellectual impairment, trouble swallowing, and vocal cord paralysis.

Causes

XP is an inherited autosomal recessive condition. This means that both parents must pass along a flawed copy of the gene for the child to show signs of XP. There are nine different genes associated with XP.

With two parents who both have the same flawed gene, there is a 1 chance in 4 of having a child with symptoms of XP.

If only one of the parents passes down a gene, then the child is an XP carrier. A carrier doesn't show signs of the condition but may later pass the gene along to their own child. When both parents are carriers, there's a 50% chance that the child will be one as well.

The genes in this case are responsible for DNA repair. DNA can get damaged by UV light and other causes. A person with XP has no working copies of a gene needed to fix the damage. The DNA damage then leads to the signs and symptoms of xeroderma pigmentosum.

Diagnosis

People may suspect they or others have XP if they are extremely sensitive to the sun. This typically is noticed in an infant who after just a short time in the sun may blister and burn, or the child may develop lots of freckles on exposed skin.

A healthcare professional may be concerned if the person also has eye-related or neurological complaints. But symptoms in each case will depend on which genes are involved.

To verify if you or a loved one has XP, your doctor will take a small skin sample from an area unexposed to the sun. The doctor will perform a test by exposing this skin sample to UV light and then looking for any changes in the DNA after exposure.

In cases in which there is a family history of XP, it's also possible to make a prenatal diagnosis. This can be done by performing an amniocentesis to retrieve a small amount of fluid from around the fetal sac of a pregnant person. The amniotic fluid can then be tested to see if DNA repair is taking place.

Treatment

Unfortunately, there is currently no cure for XP. Treatment centers around prevention. This means protecting skin from the sun and indoor sources of UV rays such as halogen and fluorescent bulbs.

Wearing protective, tightly woven clothing to cover the skin and using sunscreen with a sun protection factor (SPF) of at least 50 is recommended.

Also, regular screening exams are essential for those with XP. This means routinely undergoing the following:

• Careful skin examination should be scheduled every three to six months with an experienced healthcare professional, such as a dermatologist
• Meticulous skin screening with a family member who knows what skin cancer lesions to look out for and can screen for these regularly
• Frequent eye exams with an ophthalmologist who can check for signs of eye damage
• Regular dental visits to check for any mouth lesions
• Periodic neurological exams at the discretion of your doctor

Prognosis

With no cure, those with XP face many health challenges. If cancer lesions aren't caught in time, they may be life-threatening. For those with XP, skin cancer is a constant threat and is something that many patients die from early in life.

But if XP is caught early and preventive measures to avoid UV light are scrupulously followed, depending on the XP variant a person has, people may even survive beyond middle age.

Coping

Dealing with XP is all about avoiding the sun and other UV sources. This may mean adopting strategies like having children play outside at night instead of during the day.

Problems children with XP have in playing outdoors has given rise to a special summer spot, known as Camp Sundown, which is designed for children with UV sensitivity. It's a place where XP kids from around the world can gather. Outdoor games begin at night, while other fun activities like swimming are held indoors in UV-safe environments.

Coping strategies may also include measures such as the following:

• "Light proofing" the person's environment by putting UV film over windows and using special bulbs
• Wearing protective clothing, high-SPF sunscreen, and wide-brimmed hats outside
• Frequently screening for XP-related cancers and other issues

Summary

XP is a rare genetic condition in which those exposed to UV rays incur DNA damage that their systems cannot repair. This disease tends to affect the skin and eyes and may also promote neurological symptoms. It is often diagnosed in infants or toddlers.

People with XP tend to develop skin cancer at an early age. Prevention and screening are the main tools to avoid a cancer diagnosis.

A Word From Verywell

Those with XP must constantly be on guard against exposure to UV light, which can be challenging. Fortunately, research into this condition is ongoing. Already much is known about XP, including the identity of several genes that play a role in its development. Research soon may lead to much-needed new treatment options for people with XP.