EPP vs XP

With the advent of the new Midnight Sun movie released in theaters last week, I thought it might be helpful to give my understanding of some of the differences between Xeroderma Pigmentosum (abbreviated as XP) and the condition that I have, Erythropoietic Protoporphyria (abbreviated as EPP).

I have not yet seen the movie Midnight Sun and this is by no means an endorsement. I haven’t read a synopsis on the plot, though I know it’s a romantic movie about a girl with XP. I tend to veer towards action-packed movies over chick-flicks.

I am no medical expert on comparing these two conditions, so if anything I say is wrong please let me know and I will correct it posthaste.

Now that my disclaimers are out of the way, what are some differences and similarities between these two rare conditions?

Skin-Deep Similarity

People with both conditions share similarities in that they cannot be exposed to sunlight and that there is no standard medical treatment for either. However, that is about where the similarities end. Symptoms, genetics, degrees of sensitivity, and consequences of exposure surrounding these two respective diseases are all different.

Rarity

They are both very rare. It is estimated that 1 in 1 million people have XP in the United States, which, if you do the math, comes out to around 300-400 people. I’m not exactly sure how many are “on the books,” so to speak.

EPP is estimated to affect roughly 1 in 200,000 people in the US, though there are only about 500-600 people “on the books” of the APF database.

In Pop Culture

Despite EPP being slightly more common, more people have heard of XP. There are a few films other than Midnight Sun that surround XP. These include titles such as Dark Side of the Sun (1988) starring Brad Pitt, and the CBS television movie Children of the Dark (1994). There are other movies and TV shows that feature briefly characters with XP, and there is the relatively successful Midnight Bay Trilogy novel series by Dean Koontz, where the main protagonist has XP.

I know of no references to EPP in pop culture, other than obscure mentions.

Fatality

There is good reason for XP’s infamy. XP is fatal unless patients take restrictive precautions, and many worldwide do not live long into adulthood. (Thus it makes for a suspenseful plot hook for writers and producers.)

EPP is not necessarily fatal, though it has been known to cause dangerous liver complications especially in conjunction with alcohol consumption.

Electromagnetic Spectrum

Those with XP are unable to be exposed to ultraviolet light (100nm-400nm) from basically any source, though the sun is the biggest worry and tolerance varies.

Those with EPP are unable to be exposed to varying intensities of visible blue light (350nm-500nm) from the sunlight and certain artificial light sources, specific to the individual.

External Symptoms

Visible symptoms of XP can include pain, tumors, cancerous skin lesions, and large incidences of freckles following exposure to sunlight.

Symptoms of EPP are not always visible, though “invisible” pain should be expected with the potential for mild swelling or discoloration.

Internal Symptoms

There are also invisible symptoms of XP, which include cancer, genetic damage, and other symptoms that are not usually associated with ultraviolet exposure. People with XP have a very limited ability to filter out ultraviolet light to their organs and cells.

Visible light causes a chemical reaction within people who have EPP, which releases into the skin in the form of an agitated, energetic toxin that irritates the nerve cells. These toxins can increase the strain on the liver.

Summary

Obviously, XP is by far the more severe of the two conditions. Both conditions are life-altering for everyone involved in ways that those on the outside looking in can’t quite understand.

Obtaining a Diagnosis

Most doctors and medical specialists know very little about either EPP or XP. Finding good information for patients can be very difficult, especially for those who haven’t been officially diagnosed. Doctors aren’t all-knowing. Often, families obtain a correct diagnosis by performing their own research and then telling the doctor which tests to perform.

Where to Find More Information

XP

The best source of information for Xeroderma Pigmentosum that I know of is the Xeroderma Pigmentosum Society, at xps.org.

EPP

The best source of information for Erythropoietic Protoporphyria that I know of is the American Porphyria Foundation, at porphyriafoundation.com.

Though I haven’t seen the movie and can’t comment on its quality, I’d like to thank the producers of Midnight Sun for bringing more awareness of this condition to our society at large. Awareness helps reduce needless suffering in some who struggle to find a diagnosis. It also indirectly increases funding of research towards finding treatment or even, dare I hope, a cure for rare conditions like XP and EPP.