Xeroderma Pigmentosum: Causes, Risks & Screening
Synopsis: Information regarding Xeroderma pigmentosum, a condition characterized by extreme sensitivity to the sun, leading to high risk of skin cancer.1
Author: Thomas C. Weiss Contact: Disabled World
Xeroderma pigmentosum or, 'XP,' is a form of hereditary condition characterized by extreme sensitivity to the sun, leading to a high risk of skin cancer. Eye issues are also common. Neurologic issues such as progressive hearing loss, learning disabilities, loss of some reflexes, neuromuscular degeneration and, on occasion, tumors in the person's central nervous system, occur in some people with XP.
Xeroderma pigmentosum, or XP, is an autosomal recessive genetic disorder of DNA repair in which the ability to repair damage caused by ultraviolet (UV) light is deficient. Individuals with the disease are often colloquially referred to as Children of the Night.
People with XP are very sensitive to ultra-violet radiation, to include UVA and UVB. Exposure to even a tiny amount of UV radiation leads to severe burns and blistering, starting at a very young age. The sensitivity to UV radiation results in freckling, as well as areas of skin with lighter pigmentation. Affected people may also have very dry skin. There is a high risk of squamous cell and basal cell skin cancers, as well as melanoma.
People with XP also experience eye issues, particularly with their eyelids. As with their skin, the person's eyes are very sensitive to light, something that gives them a somewhat higher risk of cancer of the eye. Cancers of the mouth, lips and the tip of the person's tongue have also been reported. People with XP may have neurological complications to include mental disabilities, developmental disabilities and high-frequency hearing loss leading to deafness.
Causes of Xeroderma Pigmentosum (XP)
XP is a form of genetic condition. What this means is the risk of XP can be passed from generation to generation in a person's family. Mutations in at least eight different genes are known to have a role in XP. Research continues where this condition is concerned.
Usually, every cell has two copies of each gene; one inherited from the person's mother and one inherited from their father. XP follows an autosomal recessive inheritance pattern in which a mutation has to be present in both copies of the gene for the person to be affected. What this means is that both parents have to pass on a gene mutation for a child to be affected. A person who has only one copy of the gene mutation is referred to as a, 'carrier.' When both parents are carriers of a recessive mutation in the same gene, there is a 25% chance their child will inherit two mutations and therefore be affected by XP.
Options are out there for couples who are interested in having a child when they are aware that one of them carries a gene mutation that increases the risk of this hereditary cancer syndrome. Pre-implantation genetic diagnosis (PGD) is a medical procedure performed in conjunction with in-vitro fertilization (IVF). It permits people who carry a specific known genetic mutation to have children who do not carry the mutation. A woman's eggs are removed and then fertilized in a laboratory.
When the embryos reach a certain size, one cell is removed and is tested for the hereditary condition. The parents may then choose to transfer embryos that do not have the mutation. PGD has been used for more than a decade and more recently has been used for several hereditary cancer predisposition syndromes. The procedure is a complex one with physical, financial and emotional factors for couples to consider prior to beginning. An assisted reproduction specialist at a fertility clinic can provide you with more information.
Xeroderma pigmentosum (XP) is considered to be a rare genetic disorder. It is estimated that one in one million people in America have XP. It seems to be a bit more common in North Africa, Japan, as well as the Middle East.
Diagnosing Xeroderma Pigmentosa (XP)
XP is suspected when a person presents with signs of extreme sensitivity to the sun. Signs of sun sensitivity include severe burning and blistering when the affected person is exposed to even a tiny amount of sunlight, or even exposure to fluorescent lighting. Signs like these may be present in infancy. Young children might also be suspected of having XP if they have large numbers of freckles on their face. The characteristic neurological and eye issues may also increase a doctor's suspicion that someone has XP. The clinical signs of XP vary widely depending upon the type of mutations involved and the amount of exposure to the sun the person has had.
Genetic testing for mutations in the genes associated with XP is available, largely as a result of research studies. Due to the fact that there are at least eight genes associated with XP, laboratory screening tests are recommended to help determine which of the genes are likely to be causing XP in a family.
Cancer Risks Associated with Xeroderma Pigmentosum
People with xeroderma pigmentosum experience an almost 100% risk of developing multiple skin cancers if their environment is not very carefully controlled. The first diagnosis of skin cancer usually happens in a person's childhood. There might be an increased risk of cancer developing in the person's eyes, as well as around their mouth area.
Screening Options for Xeroderma Pigmentosum (XP)
Currently suggested screenings for people who are suspected or known to have XP include some different things. These screenings include the following:
- Routine neurological evaluations
- Regular eye exams by an ophthalmologist
- A careful skin examination by a doctor every 3-6 months
- Frequent skin examination by a family member who is familiar with the features of XP-associated skin cancer
Due to the great risk of multiple skin cancers, people with XP need to avoid being in unprotected sunlight. They need to cover their skin entirely and wear UV-absorbing sunglasses when they are outside. People with XP are also sensitive to UVC rays given off by some types of artificial light sources. Halogen bulbs and some fluorescent bulbs emit sufficient IV to burn some people with XP, so UV protection indoors might also be required. Screening recommendations may change over time as new technologies are developed and more is learned about xeroderma pigmentosum. It is important to contact your doctor concerning appropriate screening tests.
Fewer than 40% of individuals with the disease survive beyond the age of 20. Some XP victims with less severe cases do manage to live well into their 40s.
Symptoms Can Include:
- Dry skin
- Scaly skin
- Spider Veins
- Corneal ulcerations
- Irregular dark spots on the skin
- Limited growth of hair on chest and legs
- Development of many freckles at an early age
- Blistering or freckling on minimum sun exposure
- Rough-surfaced growths (solar keratoses), and skin cancers
- Eyes that are painfully sensitive to the sun and may easily become irritated, bloodshot and clouded
- Severe sunburn when exposed to only small amounts of sunlight. These often occur during a child's first exposure to sunlight.
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