"Did I pass this down to them?" This is the first thought that crosses the minds of parents with a sick child.

However, new mutations that neither parent possesses can sometimes develop as the child grows.

It took about 10 years to find the cause, and a researcher in South Korea has become the first in the world to uncover the underlying cause of epilepsy.

Out of 190 medical school classmates, this scientist is the only one who chose to step away from practicing medicine to pursue a path in research.

(Reported by Yeo Hyeon-gyo | Video by Kim Hye-ju | Camera: Moon Jung-do, Kim Sang-yoon | Design: Cho Seung-hyun | Produced by Intellectual Content IP Team | Sponsorship: Seo Kyoungbae Science Foundation)