Myotonic muscular dystrophy (MMD) is a genetic disorder that affects the muscles and causes weakness and wasting over time. Several synonyms for MMD include Steinert disease, dystrophia myotonica, DM, and myotonia atrophica. These terms refer to the same condition but may be used by different medical professionals and researchers. The symptoms of MMD can range from mild to severe and may affect various muscles in the body. Treatment options for MMD include physical therapy, medication, and assistive devices. Early diagnosis and management can help improve quality of life for those living with MMD.