Safety Study of Eteplirsen to Treat Early Stage Duchenne Muscular Dystrophy

Inclusion Criteria:

   - Male 4-6 years of age.

   - Diagnosis of DMD, genotypically confirmed.

   - Stable dose of oral corticosteroids for at least 12 weeks or has not received
   corticosteroids for at least 12 weeks.

   - Intact right and left biceps muscles or two alternative upper arm muscle groups.

   - Parent that is willing to provide consent and comply with study procedures.

Exclusion Criteria:

   - Use of any pharmacologic treatment (other than corticosteroids) within 12 weeks that
   may have an effect on muscle strength or function (e.g., growth hormone, anabolic
   steroids).

   - Previous or current treatment with any other experimental treatments within 12 weeks
   or participation in any other clinical trial within 6 months.

   - Major surgery within 3 months prior to the first dose of study drug, or planned
   surgery during this study which would interfere with the ability to perform study
   activities.

   - Presence of other clinically significant illness.