The Big Sick is a romantic comedy about lovers with terrible timing. As in most movies, the central couple, Emily and Kumail, is kept apart by a variety of forces: their own insecurities, cultural expectations, and, as the title alludes, the big sick. It’s no secret that illness is at the center of The Big Sick, but the mystery surrounding the puzzling illness is what drives the film forward.

So, hey: Spoilers ahead for The Big Sick.

Perhaps the biggest spoiler for the movie is the fact that the real Emily Gordon, a writer and producer who the character of Emily is based on, is still alive. The film follows the true story of Emily contracting a mysterious illness and being put into a medically induced coma while her doctors sort out what is wrong. In real life, comedian Kumail Nanjiani (who plays Kumail in the film) and Gordon had only been dating for a few months when this happened; in the film it happens after a recent break-up.

By the end of the movie (and in reality, on the eight day of her coma), Gordon is diagnosed with adult-onset Still’s disease (AOSD). And while Gordon is well today, there’s still a lot that doctors don’t know about the rare illness.

Nobody knows what causes AOSD. It’s not commonly diagnosed, and there’s no consensus on how prevalent it is in different populations. It doesn’t appear to run in families. Some people experience frequent episodes of the symptoms, while others go months or years without feeling a single effect. When they are present, however, the symptoms can be terrible.

The severity of symptoms varies across patients, but some reoccurring signs include high spiking fevers, a salmon-colored rash, muscle pain, and joint pain. In children, Still’s disease shares characteristics with juvenile rheumatoid arthritis, and can be accompanied with high fevers, fatigue, and joint swelling. AOSD mostly affects people between the ages of 16 and 35, and it’s slightly more common among women.

While some researches believe AOSD is an exaggerated response to an infection or toxic substance, others believe it’s an auto-inflammatory syndrome that could be triggered by several factors, including bacterial agents or environmental factors.

The success of treatment also varies. For some, the disease is chronic and disabling, but for others, like Gordon, symptoms just seem to disappear. Treatment can be as simple as taking non-steroidal anti-inflammatory drugs, like naproxen or ibuprofen, to treat the inflammation, but in other cases corticosteroid drugs are required for treating systemic symptoms. Gordon’s own AOSD has been manageable since she was diagnosed.

“I have to sleep the right amount and exercise the right amount, and I still occasionally get flare-ups and have to stay in bed for a few days,” she told The New Yorker. “But no more I.C.U.’s, which is pretty fucking sweet. Now I only have to go to the hospital when we’re filming a movie in one.”

When celebrities shine a light on an illness, like Angelina Jolie speaking out on having breast cancer and Charlie Sheen on HIV, there’s typically a boost in public awareness about the medical issue, which often leads to a renewed push for a cure. The Big Sick will be widely released on July 14th — we’ll have to see whether it’s popularity will drive a similar effect for AOSD.

Photos via IMDB