Can You Really Be Allergic To The Sun? 'Midnight Sun' Brings XP To The Spotlight

Movie romances wouldn't be half as sweet to watch without an obstacle for the lovers to triumphantly (or tragically not) overcome. Most of the time they're kept apart by social differences, family, friends, or epic events like war or upheaval. The upcoming teen tearjerker Midnight Sun offers a unique twist on the timeless tale — 17-year-old heroine Katie Price is allergic to daylight. Anyone watching will suspend disbelief for enjoyment, but the question is inevitable — can you really be allergic to the sun?

Though it might sound outlandish, the condition that keeps Katie isolated, xeroderma pigmentosum (XP), is a very real, and fortunately very rare, genetic disorder in which the body's ability to heal and repair exposure to ultraviolet (UV) light is deficient. In the most extreme cases, the body can't repair any damage at all. Our bodies heal themselves so frequently we take it for granted, but just as hemophiliacs can potentially bleed to death from minor cuts and bruises, those with XP can blister, burn, and form cancerous skin malignancies from very limited sun exposure.

With numerous magazine guides on how to get that summer bronze, we don't often think of it this way, but sun-kissed freckles and tans are actually signs of skin damage. The FDA puts it more bluntly: there's no such thing as a safe tanevery prolonged exposure to sunlight harms the skin. That golden glow? That's your body warding off further damage, increasing melanin production (a pigment) to block further UV ray exposure. The body then rushes to repair the trauma by sealing off exposed areas and rebuilding skin cells. Those with XP can't repair the damage, which means a frequent fate of sufferers is early death from skin cancer. Depending on whether there's additional neurological degeneration, the average lifespan of XP patients is 29 to 37 years, according to Health Research Funding.

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Midnight Sun's Katie is rarer than the usual XP patient; she has the most severe form of the disorder and is from the United States, where XP occurs once in every 1,000,000 people. The genetic disorder is far more common in Japan, where it occurs once in every 22,000 people, as Health Research Funding reports. With that stat, it's not too surprising Midnight Sun is based on a 2006 Japanese film of the same name.

In the American version, Katie's XP affects her world in a massive way. At night, Katie explores the outdoors, playing her guitar and at the start of summer, catching the eye of longtime crush Charlie. As their romance blossoms Katie's condition worsens, leaving her with a difficult choice between her health and her love for Charlie. Yet while that story might seem the stuff of big-screen drama, the reality of XP, and similar conditions, is often crushing.

Though extremely rare, XP isn't the only form of sun allergy; conditions like solar urticara and the similarly-startling polymorphous light eruption are literally allergies to the sun, causing sufferers to break out in red, painful rashes and blisters when exposed to sunlight. In an interview with The Guardian, one sufferer said, "It's such a socially isolating affliction", adding she developed a fear of going outside that grew to panicking just looking at sunny pictures online. Now, she said, her summer look is "Victorian Goth," saying, "I try to make it more like a fashion choice and less like an affliction. I think that if I can find the fun, then maybe it won’t be quite so depressing."

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There's also porphyria, another genetic disorder affecting hemoglobin production, causing purplish, mottled skin, blistering on exposure to sun, and in rarer cases, gum recession. It's thought to be a potential source for vampire myths in Europe, according to the BBC.

Those with particularly rare diseases can feel even more isolated given how few people share their symptoms and pain, but groups like the National Organization for Rare Disorders offer suggestions for counseling and commiseration. So while Katie's Midnight Sun ailment might just seem an outlandish concoction to keep lovers apart (one that didn't even work to separate Bella and actual vampire Edward in Twilight), it's a very real, very unfortunate condition that deserves our attention.