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Erythropoietic Protoporphyria

These notes are being sent to you by the Canadian Association for Porphyria because you have, or believe you may have, the condition known as erythropoietic protoporphyria (EP). The information here is intended to apply to EP in general and may include information which does not apply to your specific case. Please keep in mind that the severity of this condition varies widely and the majority of people who have inherited EP may be unaware of this fact, let alone being ill. Sometimes only the existence of a family history (occurrence of EP in a blood relative) leads to tests being done which suggest you may also have the condition, but in any event, most people with EP can live normal lives.

How Does erythropoietic protoporphyria present?
Almost always, erythropoietic protoporphyria presents as a disorder of the skin which is abnormally sensitive to sunlight. First, the symptoms of sunburn which is appreciated as tingling or burning, as well as the reddening or inflammation which follows, are both accelerated in patients with EP. The acceleration is such that direct sunlight may be tolerated only for a matter of minutes. Second, the type of sunlight which burns the skin is different: usually sunburn is caused by the shorter wavelengths of ultraviolet light but in patients with EP, the presence of porphyrins sensitizes the skin so that burning occurs with the weakest rays of ultraviolet light (the longest wavelengths) and extends into the range of visible light.

The sunburn which occurs in patients with EP may be accompanied by more inflammation with swelling, e.g. of the face, than occurs and provides some protection from the sun. However, patients with EP are at risk from severe sunburn reactions.

A small number of patients with severe EP for a number of years may develop signs of liver damage. In its most extreme form this has been fatal but fortunately, such severely affected patients are very rare.

What precautions should I take?
Sunburn is unpleasant and the symptoms of sunburn may lead you to limit your exposure to sunlight, or use some kind of protection (see below). You are probably aware that sunlight causes aging of the skin and this process will be accelerated if you have EP. Unfortunately, the ultraviolet light which damages your skin in porphyria is different (a longer wavelength) from the ultraviolet light which causes sunburn in other people. This means that the usual sunscreens do not work. If you want to use a sunscreen, it must be one of the semi-opaque screens based on zinc oxide or titanium oxide. Alternatively, you can wear light cotton gloves when you go out in the sun or simply avoid sunlight. Some relief may be obtained if you take a drug called beta-carotene which is simply the orange colouring material in carrots and other vegetables. Taking about 100mg of this harmless substance daily will give your skin a slightly orange colour but does provide some protection against the kind of ultraviolet light which causes problems in prophyria.

It is unlikely that you will develop liver problems as a complication of EP, but your doctor should monitor your liver functions and, in the event that there is any evidence of deterioration of liver function occurring, there are certain interventions which may be helpful in halting or reversing this.

The disorder of EP is made worse if you are iron-deficient. Particularly if you are female, it is important that this should not occur. In otherwise healthy persons, the iron stores in the body can be measured using the serum ferritin test and your doctor could use this to ensure that you are not iron deficient. Finally, you should be aware that EP, unlike certain other types of porphyria, does not make you more susceptible to toxic effects of various drugs. In general, you can take whatever medicinal drugs your health requires without considering yourself to be at special risk on account of EP.

How is erythropoietic protoporphyria diagnosed?
In EP the process of making heme (see the general information on porphyria is blocked at the point where iron combines with protoporphyrin to make heme). Because of this, protoporphyrin accumulates and the greatest accumulation occurs in red blood cells and in the liver. Therefore, increased protoporphyrin is found in the blood (free erythrocyte protoporphyrin), and following excretion into the intestinal tract (fecal protoporphyrin). No urine tests are relevant to this condition except to exclude other types of porphyria. If increased protoporphyrin is found in red blood cells and in a sample of your stool, the diagnosis is usually easily established. Some confusion can arise in patients suffering from lead poisoning and your doctor should be aware of this.

Will my children be affected with EP?
This is a difficult question to answer with certainty. There is still some argument regarding the nature of the inheritance of EP, i.e. whether this is dominant or recessive (see the general information on porphyria). Further, it appears that the expression of the inherited factor (the gene, that is) for EP is quite variable in different persons. This means that you may have an obvious problem with much accelerated sunburn and some damage to your skin but your children could have minimal difficulties. Of course, the opposite may also be the case.

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