An adverse event (AE) is defined as any untoward medical occurrence, whether or not considered drug related. A serious AE (SAE) is an AE that at any dose results in any of the following: death, a life-threatening AE; inpatient hospitalization or prolongation of existing hospitalization; persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions; a congenital anomaly/birth defect. TEAEs include all adverse events that start on or after the first dose of study medication, or adverse events that are present prior to the first dose of study medication, but their severity or relationship increases after the first dose of study medication up to and including 30 days after the final study medication dosing date. TEAEs were graded as mild (grade 1), moderate (grade 2), severe (grade 3), life-threatening (grade 4), or death (grade 5). TEAE relationship to study medication was classified as not related, possibly related, or probably related.

All participants who received at least one dose of study drug.

Clinically significant changes from Baseline for vital signs, physical and neurological examination findings and laboratory evaluations were recorded as AEs and are reported as part of the Safety section of this record and Outcome Measure 1.

Each interval history was intended to record any signs, symptoms, or events (e.g., falls, changes in medications or therapies) experienced by the participant since the prior study visit that were not related to study procedure(s) performed at prior study visits or study drug. Interval history may have included exacerbation or improvement in existing medical conditions (including the clinical manifestations of GNE myopathy) that might have interfered with study participation, safety, and/or positively or negatively impact performance of functional assessments.

All participants who received at least one dose of study drug. Participant "n" at each time point includes those with a yes or no response. Naïve Participants did not enter the study until Part II.

Each interval history was intended to record any signs, symptoms, or events (e.g., falls, changes in medications or therapies) experienced by the participant since the prior study visit that were not related to study procedure(s) performed at prior study visits or study drug. Interval history may have included exacerbation or improvement in existing medical conditions (including the clinical manifestations of GNE myopathy) that might have interfered with study participation, safety, and/or positively or negatively impact performance of functional assessments.

All participants who received at least one dose of study drug. Participant "n" at each time point includes those with a yes or no response. Naïve Participants did not enter the study until Part II.

Each interval history was intended to record any signs, symptoms, or events (e.g., falls, changes in medications or therapies) experienced by the participant since the prior study visit that were not related to study procedure(s) performed at prior study visits or study drug. Interval history may have included exacerbation or improvement in existing medical conditions (including the clinical manifestations of GNE myopathy) that might have interfered with study participation, safety, and/or positively or negatively impact performance of functional assessments.

All participants who received at least one dose of study drug. Participant "n" at each time point includes those with a yes or no response. Naïve Participants did not enter the study until Part II.

Each interval history was intended to record any signs, symptoms, or events (e.g., falls, changes in medications or therapies) experienced by the participant since the prior study visit that were not related to study procedure(s) performed at prior study visits or study drug. Interval history may have included exacerbation or improvement in existing medical conditions (including the clinical manifestations of GNE myopathy) that might have interfered with study participation, safety, and/or positively or negatively impact performance of functional assessments.

All participants who received at least one dose of study drug. Naïve Participants did not enter the study until Part II.