The disorder produces both weakness and tight, contracted muscles, especially in the hands. Drooping eyelids are also common. Symptoms can appear at any age and can range from mild to severe. People with the most severe form of the disease have extreme muscle weakness and many other symptoms including cataracts, small testes, premature balding, irregular heartbeats, diabetes, and mental retardation. They usually die by age 50.
Symptoms usually start in infancy.
The hands, legs, and eyelids become very stiff because of an inability to relax the muscles. Muscle weakness, however, is usually minimal. The diagnosis is made from the child's characteristic appearance, inability to relax the handgrip rapidly after opening and closing the hand, and prolonged contraction after the doctor taps a muscle. An electromyogram is needed to confirm the diagnosis. Regular exercise may be beneficial.