Estrella Salazar, a 17-year-old science whiz from a working-class town near Mexico City, was inspired by her sister to develop an app to help deaf and hard-of-hearing Mexicans communicate more easily.
Salazar's older sister, Perla, was born with a rare disorder that affects mobility and hearing, called MERRF syndrome. The 25-year-old has undergone close to a dozen surgeries followed by years of physical therapy, and was told by one sign language school that she would be unable to learn to sign due to her condition.
Salazar, whose . . .
