She was 20 years old, but Brooke Greenberg had a rare and puzzling ailment that essentially froze her in time as a toddler. Brooke, diagnosed with something called Syndrome X, died last week in suburban Baltimore, reports Time. She had the physical and mental development of a 2-year-old, explains ABC News. "In some people, something happens to them, and the development process is retarded," says a medical researcher who studied Brooke's case. "The rate of change in the body slows and is negligible." About a dozen kids worldwide are thought to have the condition.
Brooke's story had drawn national attention over the years—like this profile by NBC News—and a previous story in Discovery News reported that scientists were studying her genes to see whether they might shed light on the aging process. It's not clear what caused the syndrome, but Brooke had a series of life-threatening health scares in her first few years, including a stroke. She recovered, but soon stopped developing. Her mother once described her daughter's condition this way: "Have you ever seen the movie Groundhog Day? That's Brooke. Every day is the same thing with her. She wears the same clothes she's been wearing for years. She hasn't changed in appearance or size." (Read more Brooke Greenberg stories.)