Most days, neurologist Charles Thornton, M.D., spends some time away from his patients and heads for the laboratory, where he works with mice. It might seem an unlikely action for a doctor ultimately concerned with human health. But his forays in the laboratory have helped Thornton and his team develop a new kind of mouse that may someday help doctors around the world treat patients with myotonic dystrophy, the most common form of muscular dystrophy in adults.