The first treatment has been approved for a rare disease that causes rapid aging in children. Kids with the genetic disorder progeria typically die in their early teens, usually from heart disease. In testing, the drug extended their lives 2 1/2 years on average. The disorder is extremely rare with an estimated 400 cases worldwide. It stunts growth, causes hair loss, stiff joints, strokes and hardening of the arteries. The Food and Drug Administration approved the drug Friday. Much of the research was spearheaded by a family who set up a foundation after their son was diagnosed with the condition.