Amendment 1 This amendment corrected the timing of echocardiography assessment at the beginning of the study to be performed during screening (either Screen 1 or Screen 2 visit) and replaced the assessment during the baseline visit. This was to improve safety monitoring of the subject as results of the echocardiograph could be evaluated before the subject was randomised and received first dose of investigational drug.

Amendment 3. This amendment was implemented to update safety monitoring, technical corrections to prior versions, and corrected the protocol title.

Amendndment 4: This amendment updated the protocol with changes to eligibility to the follow-on extension study, inclusion of additional efficacy endpoints, medical monitor details and change in safety monitoring and stopping criteria. In addition, approval was not granted to recruit healthy volunteers for the accelerometry study within the DMD114117 protocol. Therefore, the healthy volunteer component was removed from the protocol and approval was sought under a separate protocol. Data will be combined with the analysis from this protocol. Minor corrections were made to errors introduced in Amendment 3.

Amendment 5: This amendment updated renal safety monitoring criteria, reporting updates for SAEs, and added clarification to the Disseminated Intravascular Coagulation criteria. Medical Monitor contact information was also updated as there was a change to the Medical Monitor.