Xeroderma Pigmentosum
Katie Whiteman
Overview
Xeroderma Pigmentosum (or XP) is a rare genetic disease that affects the body's ability to repair and protect the skin (hypersensitivity) from UV rays. Affected individuals have an increased risk of developing skin cancers. Vision is also commonly affected, and neurological defects may develop depending on the severity of the case. There are different subtypes of XP such as XPA, XPB, XPC, XPD, XPE, XPF, and XPG. There is another subtype known as XP dominant type which is dominant, not recessive. Both boys and girls can inherit this disease.
How is it inherited?
Xeroderma Pigmentosum is an autosomally recessive inherited disease, which means that an individual can only get it if both of their parents are carriers. Parents will not show symptoms because they have one regular gene, and one XP gene. The baby will show symptoms of XP because they now have two XP genes, one from each parent.
Symptoms
In most cases, the symptoms are shown very early in life, typically at around 1 or 2 years of age. In all cases, symptoms are shown before the age of 20. Symptoms consist of getting a sun burn in a short period of time, sunburns lasting more than several weeks, developing freckles or sun spots at a young age, excessive dryness of the skin, and skin cancers.
How is it diagnosed?
Xeroderma Pigmentosum (XP) is almost always diagnosed at around 1-2 years of age. Symptoms generally show immediately after birth or within the three following months. Doctors test for XP by doing certain blood tests, or measuring how damaged DNA located on the skin repairs itself. Only a few cells are needed for this test.
How is it treated?
There currently is no cure for XP, but there are methods to prevent developing skin cancer, and prevent further damage of vision and the brain. Those consist of:
-Wearing protective clothing such as long sleeves/pants
-Wearing thick clothing so that no light can reach the skin
-Using sunscreen with an SPF of 50 or higher whenever skin is exposed to the sun
-Examination by a dermatologist every 3 to 6 months
-Frequent eye examinations
-Yearly testing for potential neurological defects
Current Research
The Laboratory of Molecular Carcinogenesis conducted a three year study to prove that retinoids, a topical medication, can prevent skin cancer. They took five patients who had XP and backgrounds with certain types of skin cancer and treated them with isotretinoin over the course of three years and concluded that there was an average tumor reduction of over 63%.