Just as 13-year-old Branden Petro flops into the passenger seat of his mom's car, his eyes roll back. His face twitches uncontrollably. He curls into a fetal position.
It is his third seizure on a particularly bad day. His mother, Renee Petro, 36, jumps from her seat and runs around the car. She pulls the backpack off her son and grabs his hand.
"Squeeze my hand if you can hear me," she pleads. "Squeeze my hand, Branden. Come on baby, squeeze my hand."
Every seizure terrifies her. Any seizure could cause more brain damage. Any one could be the first sign his condition is getting worse. Other children with his condition have taken a turn for the worse and been dead within a year.