Amyotrophic lateral sclerosis (ALS), often called Lou Gehrig’s disease, is a group of rare, progressive, neurological diseases that affect neurons responsible for voluntary muscle control. McGovern Investigator H. Robert Horvitz was a principal member of the team that in 1993 identified the first gene to cause familial ALS (Lou Gehrig’s disease), and he continues to work on the search for additional ALS genes today.