SALEM, N.H. — Grady Smith arrived home to the surprise of his young life Saturday afternoon. This one made him smile, unlike the many other unexpected events the 12-year-old has had to face. The Woodbury School sixth-grader battles a potentially deadly genetic disease that destroys the protective covering surrounding nerve cells that control thinking and muscles. Some of his biggest struggles as a result of adrenoleukodystrophy, or ALD, are with hearing and communication.