Myotonic dystrophy is a genetic condition that causes progressive muscle weakness and wasting. It typically affects muscles of movement and, commonly, the electrical conduction system of the heart, breathing muscles, swallowing muscles, bowels, lens of the eye, and brain.
People with type-1 myotonic dystrophy also experience problems of their central nervous system (CNS), for example fatigue and depression, although the contribution of the CNS to symptoms is complex and poorly understood.