Abbreviated to EPP, this is a condition which means a person is sensitive to sunlight. It is a hereditary condition affecting both males and females equally, associated with the formation (-poietic) of red blood cells (erythro-). EPP itself is uncommon, along with the rest of the porphyrias and like them also, is due to the malfunction in the production of chemicals called porphyrins. It is thought that 1 in 75000 people suffer, although other estimates put the frequency at 1 in 200000.
The condition is caused by a shortage in the enzyme responsible for helping to convert protoporphyrin into haem through the addition of iron (ferrochelatase). As a result, there is a buildup of protoporphyrin within the blood stream. As the blood passes through the skin, the protoporphyrin has the ability to absorb any sunlight, and as a result, sets off a chemical reaction. In doing so, the tissue around the reaction is damaged, and interpreted by the nervous system as an itching or burning. Furthermore, if blood vessels themselves are affected, it can result in a leaking of fluid causing swelling. The exact part of the sunlight that affects the protoporphyrin in this way is not the ultraviolet light (UVB) that causes sunburn, but the longer ultraviolet wavelengths (UVA) and also visible light.
Despite being a hereditary disease, EPP is actually rare. Approximately 10% of the population have a less severely affected ferrochelatase gene, but this in itself will not cause EPP. In most cases, it will take a second, severely underactive gene, to cause EPP. Inheritance of both these genes from either parent will result in EPP.
Symptoms and Diagnosis
The main symptom of EPP is abnormal sensitivity to light. This can manifest in tingling, burning or itching pain and possible redness and swelling. Symptoms will be quick to appear, and will last for hours or maybe even days. While the symptoms last, the sufferer will continue to feel more sensitive to extremes of temperature, be they hot or cold.
EPP can usually be diagnosed from the individual story. Further medical diagnosis is performed through blood tests, and a possible stool sample. Extreme amounts of protoporphyrin are a clear indicator from the blood tests. It can also be necessary to take the same measurement from the faeces. A low blood count due to lower production of haemoglobin is also an indicator, and many people with EPP are anaemic. Regular blood tests are common to monitor the blood count, and yearly liver tests may also be arranged, as some sufferers later develop liver disease as a result. Fortunately, damage to the liver only affects around 3% of people with EPP.
Most general practitioners will be unable to diagnose EPP due to it being uncommon, and due to their lack of experience with it. You would usually be referred on to a dermatologist with more experience.
No cure for EPP exists. However, there are a number of treatments available that will help to increase the skin's natural barrier.
Oral digestion of beta-carotene capsules is one treatment available on prescription. It can cause some problems with some people, but on the whole is found to be a fairly effective treatment. It will make the skin turn a slight orange colour.
Antihistamines can be taken to relieve the symptoms somewhat, and are found to be very helpful to some people.
Phototherapy is another treatment that is available, which exposes the sufferer with careful doses of narrow band UVB or PUVA. A usual course of treatment will take place in spring, and will last for a period of about 5 weeks, with 3 treatments a week. This will allow the skin to thicken and develop a tan, resulting in a natural defence to the sunlight.
Sunblock and clothing are very effective counter measures though. Most normal sunblocks, however, will do little to protect. A good quality sunblock that protects from UVA will prove to be much more effective. As far as clothing goes, tightly woven fabrics, hats, shoes, and gloves are all advised.
EPP will sometimes clear up of its own accord, but some people are unfortunately stuck with the disease for life.