Xeroderma Pigmentosum: Causes, Symptoms, Treatment, Prognosis
What Is Xeroderma Pigmentosum?
Xeroderma Pigmentosum can be defined as a genetic pathological condition of the autosomal recessive form in which the body loses its ability to repair damage caused to the body by the ultraviolet rays of the sun. In acute cases, the affected individual is required to completely stay away from sunlight. Hence children born with this disease are also referred to "Children of Night." An affected individual will frequently suffer from basal cell carcinomas and other skin malignancies which may begin at a relatively young age. Studies indicate that malignant melanoma and squamous cell carcinoma are the most common causes of death in people affected with Xeroderma Pigmentosum.
What Are The Causes Of Xeroderma Pigmentosum?
Xeroderma Pigmentosum as stated comes under the disorders of the autosomal recessive type meaning that the affected child needs to inherit copies of the defective gene from each parent. Under normal circumstances, the UV rays from the sun damages the DNA in the skin cells and the body is fully armed to repair this damage; however, in cases of Xeroderma Pigmentosum this ability is impaired and the body is not able to repair the damage resulting in the skin becoming extremely thin and also some type of skin patches may develop. This disease also tends to cause a condition called as telangiectasia or skin cancer.
Which Are The Genes Involved In The Development Of Xeroderma Pigmentosum?
As stated, Xeroderma Pigmentosum is a pathological condition in which the ability of the body to repair the damaged DNA due to UV rays of the sun is lost. The ability of the body to repair the damaged DNA is lost as a result of mutations in genes whose function is to repair the damaged DNA. With passage of time, as the damaged DNA is not repaired it results in malfunction of cells making them cancerous. Majority of the genes related to development of Xeroderma Pigmentosum belong to a process called as Nucleotide Excision Repair or NER. These genes produce a variety of proteins which play different roles in repairing the damaged DNA. These proteins identify the extent of damage, reach the damaged part of the DNA, excise the abnormal parts of the DNA, and then repair the DNA. This is the normal functioning of the genes that are the part of the NER. In Xeroderma Pigmentosum, the genes present in the NER prohibit cells from conducting the repair process. The clinical features of Xeroderma Pigmentosum are observed due to malfunction of these genes to repair the damaged DNA. In cases, when the ultraviolet rays of the sun damage the genes which are responsible for controlling cell growth and division it results in abnormal growth of the cells causing tumors. Some neurological abnormalities are also observed to be as a result of this damage to the DNA even though the brain is not exposed to direct sunlight, although neurological abnormalities due to Xeroderma Pigmentosum is still a matter of ongoing research.
There are around eight genes identified, the mutations in which causes Xeroderma Pigmentosum of which these three are most prominent i.e., the XPC, POLH, or the ERCC2 genes.
What Are The Symptoms Of Xeroderma Pigmentosum?
Some of the symptoms of Xeroderma Pigmentosum are:
- A non-healing sunburn which forms even with slight exposure to sunlight
- Development of blisters with minimal sun exposure
- Discolored skin patches
- Crusting of skin
- Scaling of skin
How Is Xeroderma Pigmentosum Diagnosed?
To diagnose Xeroderma Pigmentosum, the treating physician will take a detailed history where the treating physician may enquire about a family history of this disease. The physician will also perform a physical examination to look at the affected areas of the skin. The treating physician may then refer the individual to an ophthalmologist who will perform a detailed ophthalmological exam which in cases of Xeroderma Pigmentosum will reveal
- Clouding of cornea
- Presence of Keratitis
- Lid tumors
If there is a family history of Xeroderma Pigmentosum and in order to find out if an unborn child has this disease then the below mentioned tests might be conducted:
- Amniotic cell culture.
Apart from the above tests, the below mentioned tests can also confirm the presence of Xeroderma Pigmentosum:
- Culturing of skin fibroblasts
- Skin biopsy.
What Is The Treatment For Xeroderma Pigmentosum?
Children affected with Xeroderma Pigmentosum need to completely stay away from sunlight as even minimal exposure can cause symptoms. In situations where children with this disease need to go out in the sun then it is imperative that they wear enough clothing to protect them from directs rays of the sun. They also require high protection sunscreens and extremely dark sunglasses. Apart from this the physician may give medications to prevent precancerous growths due to Xeroderma Pigmentosum.
What Is The Overall Prognosis Of Xeroderma Pigmentosum?
Approximately 35% of people with Xeroderma Pigmentosum live beyond their teens whereas some individuals with mild form of this disease live well up into their 40s.
Does Xeroderma Pigmentosum Affect The Fertility Of A Person?
The answer to the above question is no. This disease does not affect the fertility or potency of an individual. Majority of the people with Xeroderma Pigmentosum tend to have normal sexual development as well as functioning and are able to have children. The possibility of an individual with this disease having a child with Xeroderma Pigmentosum is quite small.