An AE was any untoward medical occurrence in a participant who received study drug without regard to possibility of causal relationship. Severity of an AE was classified as: mild (does not interfere with usual function), moderate (interferes to some extent with usual function) and severe (interferes significantly with usual function). Drug-related AEs: AEs with a possible or probable relationship to study drug. Serious AEs: death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, persistent or significant disability or incapacity, a congenital anomaly or birth defect, or an important medical event that jeopardized participant and required medical intervention. TEAE: AE that occurred or worsened in the period extending from first dose of study drug in this study to 6 weeks after last dose of study drug in this study. A summary of other non-serious AEs and all serious AEs, regardless of causality is located in Reported AE section.

As-treated population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e.

Laboratory parameters tests included hematology, biochemistry assay (hepatic, renal, and serum electrolyte values), adrenal assays, and urinalysis. Clinical significance was defined as per investigator's judgement.

As-treated population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e.

The 6MWD test was performed in a 30 meters long flat corridor, where the participant was instructed to walk as far as possible, back and forth around two cones, with the permission to slow down, rest, or stop if needed. Ambulation was assessed via the 6MWD test following standardized procedures by measuring the 6MWD in meters. Participants were not permitted to use assistive devices (walker, long leg braces, or short leg braces) during the 6MWD test.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

The SAM is a pedometer (worn on the ankle) that continuously records the number of steps per time interval. Participants were instructed to continue to wear the SAM for at least 9 consecutive days. SAM was used to record the number of strides/minute following each visit. A stride is the leg motion that begins when the foot with SAM leaves the floor and ends when the same foot touches the floor again (that is, a stride generally equals 2 steps). Mean activity period/day/visit was computed for each participant. For each day, an active period was defined as the first time after 3:00 AM that greater than (>) 2 strides/minute were recorded to the last time prior to midnight that >2 strides/minute were recorded. Days were deleted on which such an active period was less than (<) 50 percent (%) of the mean active period across all days for that participant's visit.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

The SAM is a pedometer (worn on the ankle) that continuously records the number of steps per time interval. Participants were instructed to continue to wear the SAM for at least 9 consecutive days. SAM was used to record the number of strides/minute following each visit. A stride is the leg motion that begins when the foot with SAM leaves the floor and ends when the same foot touches the floor again (that is, a stride generally equals 2 steps). Mean total step count/day/visit during the active periods was computed for each participant. For each day, an active period was defined as the first time after 3:00 AM that >2 strides/minute were recorded to the last time prior to midnight that >2 strides/minute were recorded. Days were deleted on which such an active period was <50% of the mean active period across all days for that participant's visit.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

The SAM is a pedometer (worn on the ankle) that continuously records the number of steps per time interval. Participants were instructed to continue to wear the SAM for at least 9 consecutive days. SAM was used to record the number of strides/minute following each visit. A stride is the leg motion that begins when the foot with SAM leaves the floor and ends when the same foot touches the floor again (that is, a stride generally equals 2 steps). Mean total step count/hour during the active periods for the days in a visit was computed for each participant. For each day, an active period was defined as the first time after 3:00 AM that >2 strides/minute were recorded to the last time prior to midnight that >2 strides/minute were recorded. Days were deleted on which such an active period was <50% of the mean active period across all days for that participant's visit.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

SAM is a pedometer (worn on the ankle) that continuously records the number of steps per time interval. Participants were instructed to continue to wear the SAM for at least 9 consecutive days. SAM was used to record the number of strides/minute following each visit. A stride is the leg motion that begins when the foot with SAM leaves the floor and ends when the same foot touches the floor again (that is, a stride generally equals 2 steps). The maximum continuous 10-minute, 20-minute, 30-minute, and 60-minute total step counts were computed for each participant. For each day, an active period was defined as the first time after 3:00 AM that >2 strides/minute were recorded to the last time prior to midnight that >2 strides/minute were recorded. Days were deleted on which such an active period was <50% of the mean active period across all days for that participant's visit.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable for specified categories.

SAM is a pedometer (worn on the ankle) that continuously records the number of steps per time interval. Participants were instructed to continue to wear SAM for at least 9 consecutive days. SAM was used to record number of strides/minute following each visit. A stride is leg motion that begins when the foot with SAM leaves the floor and ends when the same foot touches the floor again. Percentage of time during active periods spent at no activity (0 steps/min), low activity (≤15 steps/min), medium activity (16-30 steps/min), and high activity (>30 steps/min) were computed for each participant. For each day, an active period was defined as first time after 3:00 AM that >2 strides/minute were recorded to the last time prior to midnight that >2 strides/minute were recorded. Days were deleted on which such an active period was <50% of the mean active period across all days for that participant's visit.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable for specified categories.

If the time taken to perform this test exceeded 30 seconds or if a participant could not perform this test due to disease progression, a value of 30 seconds was used. Change from baseline data has been reported.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

If the time taken to perform this test exceeded 30 seconds or if a participant could not perform this test due to disease progression, a value of 30 seconds was used. Change from baseline data has been reported.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

If the time taken to perform this test exceeded 30 seconds or if a participant could not perform this test due to disease progression, a value of 30 seconds was used. Change from baseline data has been reported.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

If the time taken to perform this test exceeded 30 seconds or if a participant could not perform this test due to disease progression, a value of 30 seconds was used. Change from baseline data has been reported.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable at specified timepoints.

The heart rate was measured with a Polar RS400 heart rate monitor, which consists of a transmitter strap worn around the chest and a wristwatch receiver. The monitor produces a digital text file with 1 value per minute that represents the mean heart rate for that minute. Mean heart rates values were collected prior to, during, and after the 6MWT. The participant rested for 5 minutes in a sitting position prior to the 6MWT, and the mean heart rate for the last minute of this rest period was collected and documented as the resting heart rate. During the 6MWT, the mean heart rate was collected and documented as the active heart rate. After completing the 6MWT and resting for 3 minutes, the mean heart rate for 1 minute was collected and documented as the recovery heart rate.

Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and had sufficient baseline and on-treatment data in Study 007e to assess measure of interest, excluding participants who had lost all independent ambulation. 'Number analyzed'=participants evaluable for specified categories.

Basic attention and working memory was measured using the digit span task. A series of digits (0-9) were presented to the child in an auditory format only. The task had 2 parts; in the forward condition, the child 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. A raw score of the total number of correct responses was converted to an age-scaled-score (z-score) by subtracting the corresponding mean and dividing by the corresponding standard deviation of a reference population for that age.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable for specified categories.

HRQL was measured via the PedsQL. The generic core module (including physical, emotional, social and school functioning scales) comprises 23 questions and the fatigue-specific module (including general fatigue, sleep/rest fatigue, and cognitive fatigue scales) comprises an additional 18 questions. The PedsQL was completed by both the participant and/or a parent/caregiver. Examples of items in each of the generic core module scales include: "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 Likert response scale from 0 (never a problem) to 4 (almost always a problem). Scores were transformed on a scale from 0 to 100 (0=100, 1=75, 2=50, 3=25, 4=0), with higher scores indicating better health-related quality of life. Change from Baseline was calculated by subtracting the Baseline value from the value at Week 60.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable for specified categories.

HRQL was measured via the PedsQL. The generic core module (including physical, emotional, social and school functioning scales) comprises 23 questions and the fatigue-specific module (including general fatigue, sleep/rest fatigue, and cognitive fatigue scales) comprises an additional 18 questions. The PedsQL was completed by both the participant and/or a parent/caregiver. Examples of items in each of the generic core module scales include: "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 likert response scale from 0 (never a problem) to 4 (almost always a problem). Scores were transformed on a scale from 0 to 100 (0=100, 1=75, 2=50, 3=25, 4=0), with higher scores indicating better health-related quality of life. Change from Baseline was calculated by subtracting the Baseline value from the value at Week 48.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable for specified categories.

HRQL was measured via the PedsQL. The fatigue-specific module (including general fatigue, sleep/rest fatigue, and cognitive fatigue scales) comprises an additional 18 questions. PedsQL was completed by both the participant and/or a parent/caregiver. 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 Likert response scale from 0 (never a problem) to 4 (almost always a problem). Scores were transformed on a scale from 0 to 100 (0=100, 1=75, 2=50, 3=25, 4=0), with higher scores indicating less fatigue. Total score was the sum of all items over the number of items answered on all scales. Change from Baseline was calculated by subtracting the Baseline value from the value at Week 60.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable at specified timepoints.

HRQL was measured via the PedsQL. The fatigue-specific module (including general fatigue, sleep/rest fatigue, and cognitive fatigue scales) comprises an additional 18 questions. The PedsQL was completed by both the participant and/or a parent/caregiver. 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 likert response scale from 0 (never a problem) to 4 (almost always a problem). Scores were transformed on a scale from 0 to 100 (0=100, 1=75, 2=50, 3=25, 4=0), with higher scores indicating less fatigue. Total score was the sum of all items over the number of items answered on all scales. Change from Baseline was calculated by subtracting the Baseline value from the value at Week 60.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable at specified timepoints.

Activities of daily living were measured using the EK scale in all participants who were unable to complete the 6MWT at Screening/Baseline on Day 1. 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 the arms, 6) ability to use the 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 performed the tasks of daily life (as described by Categories 1 to 9) and how he perceived his well-being (as described by Category 10).

Non-Ambulatory 007e population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, and who had lost all independent ambulation prior to entering Study 007e. 'Number analyzed'=participants evaluable at specified timepoints.

TSQM consisted of 14 questions about treatment satisfaction with drug in 4 domains: Effectiveness (Questions 1-3 scored as 1 [extremely dissatisfied] to 7 [extremely satisfied]), Side Effects (question 4 scored as 0 [no] or 1 [yes]; question 5 scored as 1 [extremely bothersome] to 5 [not at all bothersome]; questions 6 - 8 scored as 1 [a great deal] to 5 [not at all]), Convenience (questions 9 and 10 scored as 1 [extremely difficult] to 7 [extremely easy]; question 11 scored as 1 [extremely inconvenient] to 5 [extremely convenient]) and Global Satisfaction (question 12 scored as 1 [not at all confident] to 7 [extremely confident]; question 13 scored as 1 [not at all certain] to 5 [extremely certain]; question 14 scored as 1 [extremely dissatisfied] to 5 [extremely satisfied]). The scores of each of the domains were added together and an algorithm was used to create a score of 0 to 100, with higher scores indicating better treatment satisfaction.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable for specified categories.

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.

Evaluable population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e, who had sufficient baseline and on-treatment data in Study 007e to assess the measure of interest. 'Number analyzed'=participants evaluable at specified timepoints.

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

As-treated population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e.

Plasma samples for the determination of ataluren concentrations were analyzed at the bioanalytical laboratory for ataluren parent drug using a validated high performance liquid chromatography with tandem mass spectrometry (HPLC/MS-MS) method with a lower limit of quantitation (LLOQ) of 0.5 micrograms/millilitre (mcg/mL). Values below the LLOQ were set to 0.

As-treated population included all participants who completed Study 007 and received ≥1 dose of ataluren in Study 007e. 'Number analyzed'=participants evaluable at specified timepoints.