Emma Paven had never met anyone with the mysterious syndrome she has lived with since she was 9 years old.

Then a few months ago, while walking by a first-grade classroom in the school where she’s a teacher’s aide, the 19-year-old Hingham resident saw a little girl on her knees, staring at the bright LED lights above her. She was rapidly waving her hand back and forth in front of her face, as if repeatedly brushing hair out of her eyes.

“My heart dropped to my stomach,’’ Paven said. It was as if she were looking at a younger version of herself.