Xeroderma pigmentosa (XP) is a rare genetic condition which is characterised by extreme sun sensitivity. It manifests as skin pigmentation changes, sunburns and an increased risk of skin cancers. Approximately one quarter of affected individuals will have associated neurological manifestations.
It is caused by a mutation on one of eight genes. It is autosomal recessive, meaning two copies of the defective gene are needed to develop the disease. If both copies are present, the disease occurs 100% of the time.
XP occurs in all ethnic and gender groups.
People with Xeroderma Pigmentosum tend to have problems with their eyes which can range from dry eyes and sensitivity to light, to visual impairment. Certain types of Xeroderma Pigmentosum may make one more prone to neurological problems. This can manifest as intellectual impairment, deafness, and difficulty balancing and walking. Finally, people who have Xeroderma Pigmentosum are also at increased risk of cancers in the mouth and eyes.
In some individuals, XP may present as a reddening in the first few weeks of life due an exaggerated sunburn response. In other individuals, they will often develop freckle-like pigmentation on sun-exposed areas such as the forehead and cheeks in early childhood, usually before the age of 2 years.
If XP is suspected, you or your family member may have a skin biopsy performed and referred to a genetics clinic and offered a blood test. This blood test looks to see if the faulty gene is present and can help confirm the disease.
Other associated skin findings are hypo- and hyperpigmentation, warty growths and accelerated photoaging. The eyes may also be affected.
In 25% of individuals, neurological signs will be present such as reduced deep tendon reflexes, progressive hearing loss, and difficulty remembering things, balance impairment and acquired decrease in size of the brain (microcephaly).
Individuals with XP are at a significantly increased risk of non-melanoma and melanoma skin cancer.
Strict lifetime sunlight avoidance is key to reducing the risk of associated sequalae.
Individuals with XP need to take precautions to minimise any sun exposure, including:
- Wearing SPF 50+ and sun-protective clothing such as long sleeves, wide-brimmed hat and wraparound sunglasses.
- Ensuring access to SPF 50+ at all times.
- Avoiding outdoor occupations or recreational activities.
- Avoiding sun exposure through car or building windows, either through drawing curtains and/or applying UV protective tinting to windows.
- Using lightbulbs which emit lower levels of UV.
- Avoiding going outdoors during the middle of the day, and planning travel and activities in periods of low sunlight.
Awareness of your own skin is very important if you suffer from XP, to detect skin cancers early.
It is also worse in people who smoke, and therefore smoking cessation is crucial.
Individuals with XP must also take a vitamin D supplement, as they will be avoiding the sun.
Xeroderma Pigmentosum patients who do not suffer from neurological problems generally have a normal lifespan. The most common causes of death in patients with Xeroderma Pigmentosum is metastatic melanoma and neurodegeneration. However, patients who are diagnosed early and who stick to strict sun protection regimes have good outcomes.
Further information and links to support networks can be found on the Xeroderma Pigmentosum Society, Inc website: https://www.xps.org/
This information has been written by Dr Kirsty Wark, Dr Hiva Fassihi and Dr Deshan Sebaratnam
Published October 2020