By 12, veins were starting to pop out of her legs, and the other kids started asking how it felt to be old. She was rail-thin, but she could still do most of the things normal kids did. A video of her 12th birthday shows Jill at a pool party, her cannonball displacing a teacup of water.

Later that year, her muscles started to fail again. “I can remember just getting on a bike I’d always ridden,” Jill says, “and feeling like someone came up behind me and just threw me into the handlebars.” Suddenly she couldn’t hold her upper body up over the bike. She invited a friend to go roller skating, and found that she couldn’t stand up on the skates. Over the course of a few weeks, Jill had completely lost the ability to ride a bike and skate.

Something was “terribly wrong,” as she put it, but she didn’t even bother to tell her parents about it. Other people went to doctors and got solutions. That had never happened for Jill, so she started looking for answers on her own, the way a kid would. She started bringing home books from the library on poltergeists and other supernatural phenomena. “I remember it really freaked out my dad at one point,” she says. “He was like, ‘Well, are you into the occult, or what?’ It was nothing of the sort.” It was just that she couldn’t explain the forces acting on her body. She was fascinated by the stories of people bedeviled by inexplicable maladies or situations. Jill says, “You know, I believe them.”

* * *

By the time she left for college, Jill had maxed out at 5-foot-3 and 87 pounds. She had long since moved on from poltergeists, but not from the knowledge that if she was going to figure out what was happening to her body, she would have to go it alone.

Almost as soon as she arrived on campus, she hit the library. She spent more time there than in classes—about 25 hours a week, as she recalls it, poring over every textbook and scientific journal she could find on muscle disease. She did this for months, going article by article, like a police officer driving up and down every street doing a grid search. But nothing quite fit. Not until she came to a paper in the journal Muscle and Nerve, on a rare type of muscular dystrophy called Emery-Dreifuss. “Looking at the pictures,” Jill says, “it was a very startling thing to realize I’m seeing my dad’s arm.”

Jill’s dad was thin, but the muscles in his forearm and hand were unusually well-defined. Jill would call it a “Popeye arm” when she was a little girl. In another paper she saw that Emery-Dreifuss patients often had that same trait; it was even referred to as a Popeye-arm deformity. But she didn’t see pictures of women with the disease.

The Muscle and Nerve paper described the three hallmarks of Emery-Dreifuss patients: They couldn’t touch their chins to their chests, or their heels to the floor, and their arms were perpetually bent at the elbow. The medical term is “contractures.” In middle school, Jill’s head once got stuck for a while so that she was looking up.

“I’m getting chills reading this,” Jill says, “I’ve got all three.” Picture a Barbie doll —arms always bent, feet slanted to fit into high heels, and a stiff neck. It’s “very ironic that we give this to little girls and say this is perfect, and we’re actually handing them a doll that has a genetic disorder.”