Abstract
Two boys with Becker's muscular dystrophy had a dramatic and sustained improvement in strength with therapeutic use of prednisone. Both had documented Xp-21 defects on DNA testing. Concurrently with improvement, there was a decrease in their serum creatine kinase levels. One patient had two muscle biopsies, the first before prednisone treatment and the second during treatment. Both biopsies demonstrated an immunoblot decrease in the quantity of muscle dystrophin. Routine histology on the first biopsy was consistent with muscle dystrophy, and the second biopsy was normal. These two patients suggest that a small percentage of patients with Becker's muscular dystrophy have a dramatic and sustained improvement in strength with the use of therapeutic corticosteroids. All patients with Becker's muscular dystrophy should be given a careful trial of prednisone to define those who benefit.