EPP and porphyrin damage
What's UP Doc? Is a regular column where we feature a patient question along with a response from a member of the UPA Scientific Advisory Board.
My son has Porphryia and one question I ask myself and have had others ask me when telling them about EPP is:
We know what the extra porphyrins are doing when they have a reaction, and it makes their skin hurt but are they doing any damage on the inside of the body? For example, my mom always thought that if Mitchell was out in the sun and had an “attack” it would hurt his liver, but I know of other people with EPP that avoid light altogether and had their liver fail.
Thanks for asking this question! Here is a detailed response from UPA Scientific Advisory Board member Dr. Amy Dickey, Porphyria Expert (Massachusetts General Hospital (MGH) and an Instructor of Medicine at Harvard Medical School (HMS)
This is an incredibly important topic for patients with EPP like me. The short answer is no, light exposure does not increase an EPP patient’s risk of liver disease. Why is that? In EPP, a substance called protoporphyrin is made in the bone marrow and builds up in the body, especially in the blood. It gets deposited in the skin, and it is excreted in the stool after being filtered through the liver. The protoporphyrin in the skin reacts with light and causes internal damage and skin pain. The light is reacting with protoporphyrin that is already sitting in the skin and the small blood vessels in the skin, and light does not increase the levels of protoporphyrin. Separately from what is happening at the skin, protoporphyrin can get clogged in the liver ducts, causing liver injury and liver failure. Because light does not affect the amount of protoporphyrin in the body, it doesn’t change the risk of protoporphyrin getting clogged in the liver ducts. Some people with EPP have really high levels of protoporphyrin all the time, for reasons nobody understands. As compared to other EPP patients, these people are more likely to have liver failure and they’re also more likely to be especially sensitive to light. That being said, light exposure and painful EPP reactions isn’t what is causing liver damage in these patients.
One reason this topic maybe confusing to people is that in other types of porphyria, like acute intermittent porphyria (AIP), damaging substances called porphyrins and porphyrin precursors can increase in the body because of stress, certain medications, and other factors. The levels of these substances may otherwise be normal. In EPP, though, that doesn’t happen, and protoporphyrin levels are increased to about the same levels throughout a person’s life. Light doesn’t change them.
Light exposure in EPP is extremely painful and causes skin damage that can sometimes leads to permanent scarring. Otherwise, light exposure isn’t dangerous in EPP. As an EPP patient who has experienced the severe pain of EPP reactions, it’s really hard for me to completely believe that too much light exposure couldn’t somehow kill me. However, as a doctor and a researcher I know that this isn’t possible. There’s also no reason to think that light causes damage anywhere else besides the skin in EPP.
Thank you to Dr. Dickey for this What's UP Doc? answer! Do you have a question for a porphyria expert? Send it to info@porphyria.org.
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