An adverse event (AE) is any untoward, undesired, unplanned clinical event in the form of signs, symptoms, disease, or laboratory or physiological observations occurring in a participant, participating in a clinical study with study drug, regardless of causal relationship. TEAEs were AEs occurred after study drug administration that were absent before treatment or that worsened relative to pre-treatment state, up to Week 28 until evaluation (when last cohort had 26-week evaluation and data management performed within 4 weeks) completed.

GMFM was measured using GMFM-88 item scores and summed to calculate a total GMFM-88 score. For each GMFM-88 item, the score was between 0 (minimal) to 3 (maximum). The total GMFM-88 score was between 0 (minimal) and 264 (maximum). The decrease in GMFM score over time indicates worsening of disease over time. Relative change from baseline at Week 26 was calculated as percentage change from baseline divided by the age-difference in months between first and last visit. Adjusted mean and 95 percent (%) confidence intervals were reported.

Relative change from baseline at Week 26 was calculated as percentage change from baseline divided by the age-difference in months between first and last visit. Adjusted mean and 95 percent (%) confidence intervals were reported.

Number of participants with shifts between negative (value=0) and positive (value=1) values in urine sulfatide levels from baseline at Week 26 is reported.

Mullen's Scales of Early Learning is used to assess performance and learning ability in young children. The scale consisted of 144 items that had specific scoring criteria for each item. The scores were converted to T-scores with a decrease in score indicating worsening of disease. Relative change from baseline at Week 26 was calculated as percentage change from baseline divided by the age-difference in months between first and last visit. Adjusted mean and 95 percent (%) confidence intervals were reported.