At one time, doctors thought Becker dystrophy might be an entirely different disease from Duchenne. But, soon after the gene for Duchenne was isolated, researchers found that people with Becker dystrophy had defects in the same dystrophin gene and that the same dystrophin protein was affected as in Duchenne. The gene defects in Becker are different from those in Duchenne, so that some working dystrophin is made. Muscle weakness and wasting generally start in the shoulders, upper arms and lower legs. Weakness may later spread to involve the muscles of the chest and pelvic area.
Contractures appear early in the disease, usually involving the ankle and elbow.
Unlike other forms of muscular dystrophy, contractures in Emery-Dreifuss dystrophy often appear before the person experiences significant muscle weakness. Physical therapy is beneficial in minimizing the contractures. This is followed by other signs of eye and facial muscle weakness, as well as by difficulty in swallowing. The later stages of this slowly progressive disease may include weakness in the pelvic and shoulder muscles. Swallowing problems can lead to choking and recurrent pneumonia.