These diseases typically begin in young adulthood and progress quite slowly. It usually takes two decades or more after onset before individuals are greatly incapacitated. They both involve shoulder and hip muscles, and the latter dystrophy affects the facial muscles as well. Myotonic dystrophy and ocular dystrophy are rare forms which begin in young adults and progress slowly, and usually do not cause severe disability for decades. Myotonic dystrophy primarily affects the muscles of the hands, and is often accompanied by cataracts in the eyes and facial muscle paralysis.
Mental retardation is frequently present.
Ocular dystrophy normally affects the eye and throat muscles. In Duchenne's, limb-girdle and facioscapulohumeral dystrophy, most functional limitations result from weakness of the shoulder and hip muscles. Ambulation becomes difficult and eventually impossible without a wheelchair. Activities of daily living and vocational tasks involving ambulation and reaching skills become increasingly difficult and often impossible. Physical therapy, exercise and a proper rehabilitation regimen can help maintain function.