A TEAE is any untoward medical occurrence or undesirable event(s) experienced in a participant that begins or worsens following administration of the study drug or study treatment, whether or not considered related to the treatment by the Investigator. A serious adverse event (SAE) was an adverse event (AE) resulting in any of the following outcomes or deemed significant for any other reason, death, initial or prolonged inpatient hospitalization, life-threatening experience (immediate risk of dying), or persistent or significant disability/incapacity not related to nmDBMD. AEs included both SAEs and non-serious AEs. AEs were classified according to National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0 (CTCAE) and coded using the Medical Dictionary for Regulatory Activities (MedDRA). A summary of serious and all other non-serious adverse events, regardless of causality, is located in the Reported Adverse Events module.

All enrolled participants who received at least 1 dose of study drug.

Arm and hand function were assessed using the Jebsen test, a standardized clinical evaluation of tasks important to daily living. The test comprises of unilateral subtests performed with each hand (the dominant [DOM] hand and the non-DOM hand): moving and stacking light (250 grams) and heavy (500 grams) objects; picking up small, commonly encountered objects; stacking checkers; simulated feeding; simulated page turning; and writing. Participant performance of each task was timed. Longer time to complete the test indicates worse hand function.

All enrolled participants who received at least 1 dose of study drug and with evaluable upper limb function tasks data.

Upper extremity function was assessed using the Brooke Upper Extremity Functional Rating Scale, following standardized procedures. The Brooke Upper Extremity Functional Rating Scale graded arm and shoulder function from 1 to 6, with higher values indicating less function. A rating of "1" was used when the participant was able to abduct his arms in a full circle until they touch above his head, whereas a rating of "6" was used when the participant was unable to raise his hands to his mouth and had no useful function of hands.

All enrolled participants who received at least 1 dose of study drug and with evaluable upper limb function tasks data.

Activities of daily living after loss of ambulation were measured using the EK scale. The EK scale is an ordinal scale ranging from 0 to 30 points where 0 represents the highest level of independent function and 30 the lowest. The scale consists of 10 categories (each scored 0 to 3), involving different functional domains including 1) ability to use wheelchair, 2) ability to transfer from wheelchair, 3) ability to stand, 4) ability to balance in the wheelchair, 5) ability to move arms, 6) ability to use hands and arms when eating, 7) ability to turn in bed, 8) ability to cough, 9) ability to speak, and 10) physical well-being. The administration of the EK scale consisted of an interview of the participant to capture how he performs the tasks of daily life (as described by Categories 1 to 9) and how he perceives his wellbeing (as described by Category 10). The interviewer observed the participant and assigned the final score for the tasks that could be observed in the clinic.

All enrolled participants who received at least 1 dose of study drug and with evaluable EK Scale data.

Goniometry was performed to test active and passive range-of motion (RoM) of the left (L) and right (R) shoulder, elbow, and wrist following standardized procedures. The observed angle for passive and active motion for each joint was measured in degrees. Greater degree of motion indicates better response.

All enrolled participants who received at least 1 dose of study drug and with evaluable range of motion data.

Upper extremity myometry was performed using a hand-held dynamometer following standardized procedures. The measured strength (peak force) was reported in Newtons. There are 0.22 pounds (lbs) in 1 Newton and approximately 10 Newton (9.80665 Newton) in 1 kilogram (kg). The threshold/range of the hand-held dynamometer is 0 to 500 Newtons. Bilateral assessments were done, and 3 measurements were recorded from each muscle group on each side, when possible. When the measurements were done in duplicate or triplicate, the best value was used. Greater value indicates better measurement.

All enrolled participants who received at least 1 dose of study drug and with evaluable upper extremity myometry data.

Hand fine motor coordination and dexterity were assessed using the 9HPT using standardized procedures. The 9HPT is a unilateral test in which 9 pegs were placed in a board and then removed with the dominate and non-dominate hand within a 5-minute time limit. The amount of time required to put the pegs in the holes and remove them again with each hand was recorded. Each test was conducted twice per hand. Longer time to complete the test indicates worse hand fine motor coordination and dexterity.

All enrolled participants who received at least 1 dose of study drug and with evaluable 9HPT data.

Pulmonary function was assessed as FVC in participants by spirometry using a study-specific spirometer. Multiple tests were conducted, if needed.

All enrolled participants who received at least 1 dose of study drug and with evaluable spirometry data. Data was not collected at Week 6 as no participants were evaluable at this timepoint.

Cardiac function was assessed by echocardiography, which included standard parameters (for example, ejection fraction, left ventricle diastolic and systolic dimensions), as well as parameters integrating Doppler flow analysis with imaging to evaluate perturbations in wall motion. A standardized data collection process harmonized data from all participating institutions and allowed for centralized review.

All enrolled participants who received at least 1 dose of study drug and with evaluable echocardiography data. Since the study was terminated early, echocardiography data were not collected after the start of study drug administration.

Heart rate was measured with the radial pulse. Following the Jebsen test, the participant rested for 5 minutes in a sitting position, and the heart rate for the last minute of this rest period was collected as the resting heart rate.

All enrolled participants who received at least 1 dose of study drug and with evaluable heart rate data.

A series of digits (0-9) were presented to the participant in an auditory format only. The task had 2 parts: in the Forward Condition, the participant was requested to repeat back the digits in the order they were presented, and in the Backward Condition, he was requested to reverse the order of presentation.

All enrolled participants who received at least 1 dose of study drug and with evaluable verbal memory and attention data. The test was repeated until the participant had 0 correct responses, which was up to 7 times for the Forward Condition and up to 5 times for the Backward Condition at Baseline and at Week 6.

Health-related quality of life (HRQL) was measured by the Pediatric Quality of Life Inventory (PedsQL) Inventory Generic Core Scale. The generic core module comprised of 23 questions evaluating physical, emotional, social, and school functioning. Examples of items in each of the generic core module scales included: "It is hard for me to run"; "I feel sad or blue"; "I cannot do things that other kids my age can do;" and "It is hard to pay attention in class." Each of the generic core module items was scored on a 5-point response scale from 0 (never a problem) to 4 (almost always a problem). The appropriate age-specific version was completed. PedsQL Inventory Generic Core Scale data at Week 6 is presented.

All enrolled participants who received at least 1 dose of study drug and with evaluable PedsQL Inventory Generic Core Scale data at Week 6.

HRQL was measured by the PedsQL Multidimensional Fatigue Scale. The fatigue-specific module comprised of 18 questions evaluating general fatigue, sleep/rest fatigue, and cognitive fatigue. Fatigue-specific module obtains information relating to items such as: "I feel too tired to do things that I like to do"; "I spend a lot of time in bed"; and "I have trouble remembering more than one thing at a time." Each of the fatigue-specific module items was scored on a 5-point response scale from 0 (never a problem) to 4 (almost always a problem). The appropriate age-specific version was completed. PedsQL Multidimensional Fatigue Scale data at Week 6 is presented.

All enrolled participants who received at least 1 dose of study drug and with evaluable PedsQL Multidimensional Fatigue Scale data at Week 6.

HRQL was measured by the Individualized Neuromuscular Quality of Life Questionnaire (INQoL). The INQoL consisted of 45 questions within 10 sections. Four of the sections evaluate key muscle disease symptoms (that is, weakness, locking [myotonia], pain, and fatigue), 5 sections evaluate the degree and importance of the impact of muscle disease on particular areas of life, and 1 section asks about the positive and negative effects of treatment. A higher score indicates greater symptom impact or worse HRQL, with a range of 0-7.

All enrolled participants who received at least 1 dose of study drug and with evaluable INQoL data. Since the study was terminated early, INQoL data were not collected.

Blood samples collected for chemistry assays were used to quantify serum CK concentrations. Serum CK was assessed as a potential biomarker for muscle fragility, with a reduction in serum CK considered to be a positive outcome. The reference range was based on the age of the participant.

All enrolled participants who received at least 1 dose of study drug and with evaluable CK data. Data was not collected at Week 6 for CK Levels with the reference range of 18-363 UL as no participants were evaluable at this timepoint.

The gastrocnemius muscle was to be biopsied from 1 leg to assess for the production of dystrophin at Week 36. The production of dystrophin was to be measured by immunofluorescene staining of the sarcolemmal membrane or by Western blotting techniques with an antibody to the C-terminal portion of the dystrophin protein (excluding revertant fibers).

All enrolled participants who received at least 1 dose of study drug and with evaluable dystrophin production data. Since the study was terminated early, gastrocnemius muscle dystrophin expression data were not collected after the start of study drug administration.

Study drug compliance was assessed by the participant daily diary and quantification of used and unused study drug. Compliance was assessed in terms of the amount of drug actually taken relative to the amount that should have been taken during the study.

All enrolled participants who received at least 1 dose of study drug and with evaluable study drug compliance data.

Blood for ataluren concentrations over a 24-hour period was to be collected on Days 2 and 3 of Week 6. Analysis of the blood samples was to be conducted using a validated high performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS) method.

All enrolled participants who received at least 1 dose of study drug and with evaluable plasma data. Since the study was terminated early, steady state data were not collected at Week 6.