A Study to Find Out How BIIB141 (Omaveloxolone) is Processed in the Body and to Learn More About Its Safety in Participants With Friedreich's Ataxia Aged 2 to 15 Years Old

Exclusion Criteria

• •Have uncontrolled diabetes (haemoglobin A1c \[HbA1c\] \>11.0%).
• •Have B-type natriuretic peptide (BNP) level \>200 picograms per milliliter (pg/mL) at screening.
• •Have a history of clinically significant (CS) left-sided heart disease and/or CS cardiac disease, with the exception of mild to moderate cardiomyopathy associated with FA.
• •Presence of outflow tract obstruction defined as a peak instantaneous gradient \>50 mmHg (based on ECHO performed at screening).
• •Have taken any moderate or strong inhibitors and/or inducers of cytochrome P450 3A4 within the 7 days prior to Day 1 or plan to take during study participation (eg, itraconazole, carbamazepine, phenytoin, ciprofloxacin, grapefruit juice, cannabidiol, fluconazole, fluvoxamine, verapamil, diltiazem).
• •Have a history of CS liver disease (eg, fibrosis, cirrhosis, hepatitis), or have clinically relevant deviations in laboratory tests at screening
• •Plan to or have participated in any other interventional clinical study within the 30 days prior to Day 1.
• •Have a cognitive impairment that may preclude ability to comply with study procedures, in the opinion of the investigator.
• •Be unable to comply with the requirements of the study protocol or be unsuitable for the study for any reason, in the opinion of the investigator.
• •Have previously documented mitochondrial respiratory chain disease.
• •Have a history of thromboembolic events within the past 5 years.
• •Plan to or have taken anticoagulant therapy within 30 days prior to Day 1 with the exception of a daily low dose aspirin (up to 81 mg).
• •Plan to or have scheduled surgical treatment for scoliosis or foot deformity during the study.
• •Have had significant suicidal ideation within 30 days prior to Screening Visit, as per investigator judgment, or any history of suicide attempt.
• •For females, be pregnant or breastfeeding.
• •Part 2:
• •No discontinuation criteria have been met.
• •Safety and tolerability data from Part 1 are supportive of continuation in the judgement of the Investigator.
• •In the event of intercurrent illness or other change in health status of the participant, additional Part 1 Screening assessments may be repeated prior to initiation of Part 2, based on the judgement of the Investigator in consultation with the Medical Monitor.