Emery-dreifuss humeroperoneal muscular dystrophy: an x-linked myopathy with unusual contractures and bradycardia.

Clinical, electromyographic, and muscle biopsy findings in the two largest known families with Emery-Dreifuss humeroperoneal muscular dystrophy indicate that this is an X-linked recessive muscle disease with stereotyped clinical manifestations but with variable pathological and electromyographic characteristics. Elbow contractures, involvement of humeral muscles, hyporeflexia, and abnormal electrocardiograms are present in our patients. The disorder is associated with a potentially lethal cardiac arrhythmia that should be managed by pacemaker insertion. The skeletal muscle disease is slowly progressive and is usually not life threatening. Muscle biopsy commonly shows type I fiber atrophy. Electromyography usually indicates myopathy, though the classic findings of myopathy may not be present in every muscle.