Xeroderma Pigmentosum (XP)
What is xeroderma pigmentosum?
Xeroderma pigmentosum (XP) is a skin condition that is characterized by an extreme sensitivity to light. The eyes and areas that are most often exposed to sun are affected, and the nervous system may be affected as well.
About one of every one million people in the U.S. and Europe have XP. It is more common in Japan, the Middle East, and North Africa.
What are the symptoms of xeroderma pigmentosum?
Symptoms typically appear in infancy or early childhood, as individuals will burn within minutes of being exposed to the sun. This sunburn can last for weeks. Over time freckles, changes in pigment, and dryness will occur in the areas that are exposed to the sun. The eyes are also affected, and they will become irritated and bloodshot if they are exposed to the sun without protection. Eyelashes can fall out, and the skin around the eye may thin.
Approximately 30% of those with XP experience neurological symptoms. They may have hearing loss, issues with coordination, loss of intellectual function, difficulty with walking and movement, seizures, and issues with swallowing and talking. These symptoms tend to be progressive.
Complications are possible, as skin cancer often occurs multiple times in the lifetime of those with XP. Affected individuals may also be at a heightened risk of brain tumors. Cancer in the eyes is also a possible complication.
What causes xeroderma pigmentosum?
Eight genes have been associated with XP, and medical professionals believe there may be more. All of these genes play a role in repairing damaged DNA, making it so that they cannot fix sun damage. Many are related to nucleotide excision repair (NER). Most of the cases in the U.S. are caused by mutations in the XPC, ERCC2, and POLH genes. All associated genes are inherited in an autosomal recessive pattern.
How is xeroderma pigmentosum diagnosed?
This condition is typically diagnosed in infancy after parents or doctors notice the characteristic symptoms. Genetic testing can be used to confirm a diagnosis.
What are the treatments for xeroderma pigmentosum?
Preventing sun exposure is the best method of treatment. This means wearing protective clothing and gear, limiting time in the sun, and testing areas (home, school, work) for UV levels. Vitamin D supplements are helpful, as they replace the vitamins that are often obtained through sunlight.
Routine examinations should be performed by a dermatologist, opthamologist, and neurologist to ensure that there are no complications or developments in this condition. Other treatments are symptomatic.