Clinical stability was defined as absence of death due to disease progression or new dependency on invasive ventilation and; decline in cardiac status, motor function, and pulmonary function from baseline.

Full analysis population. Number of participants analyzed = participants with available data at Week 52 for this outcome.

Percentage of participants who were alive at Week 52, were reported. Survival rate was calculated by Kaplan-Meier estimate.

Full analysis population.

Percentage of participants, who were invasive ventilator-free at week 52, are reported. Invasive ventilation was defined as mechanical ventilatory support applied with the use of an endotracheal tube or tracheostomy. Invasive ventilator-free survival rate was calculated by Kaplan-Meier estimate.

Full analysis population. Number of participants analyzed = participants with available data at Week 52 for this outcome.

Z-Scores indicate the number of standard deviations (SD) from the mean in a normal distribution. A negative change from baseline indicates an increase in LVM-Z score. The normal range is -2 to 2 and greater than 2 may indicate left ventricular hypertrophy.

Full analysis population. Number of participants analyzed = participants with available data at Week 52 for this outcome.

GMFM-88 (88-item measure to detect gross motor function) consists of 5 components, each measured on a 4-point Likert scale.The score for each dimension was expressed as a percentage of the maximum score for that dimension.Total score ranges from 0% to 100%, where higher scores indicate better motor functions.

Full analysis population. Number of participants analysed = participants with baseline and Week 52 GMFM-88 data.

Percent predicted FVC values are reported. FVC is the volume of air that can forcibly be blown out after full inspiration in the upright position, measured in litres. Predicted forced vital capacity is based on a formula using sex, age and height of a person, and is an estimate of healthy lung capacity. Percent of predicted FVC = (observed value)/(predicted value) * 100%.

Full analysis population. Number of participants analysed = participants with baseline and Week 52 FVC data.

Percent predicted FVC values are reported. FVC is the volume of air that can forcibly be blown out after full inspiration in the upright position, measured in litres. Predicted forced vital capacity is based on a formula using sex, age and height of a person, and is an estimate of healthy lung capacity. Percent of predicted FVC = (observed value)/(predicted value) * 100%.

Full analysis population. Number of participants analysed = participants with baseline and Week 52 FVC data.