As a toddler, Philly Mayer was healthy and happy. A chubby baby, he was quick to laugh and eager to get up on his own feet. And then, before his first birthday, Philly suddenly stopped walking. His motor skills began to deteriorate. After a slew of tests and endless emotional upheaval, doctors diagnosed Philly with Spinal Muscular Atrophy, a genetic disease that occurs in an estimated 1 out of every 6,000 births and leaves the spine underdeveloped. His parents were told that he would not live...