This immunoperoxidase stain utilizes antibody to the muscle protein called dystrophin, which is present in only small amounts in this patient with Becker type muscular dystrophy. In this case, some dystrophin is made, but not normal amounts. Persons with Becker muscular dystrophy have an onset of disease in adolescence to young adulthood, and have a less severe course than persons with the Duchenne type of muscular dystrophy.