The primary purpose of this study is to evaluate the safety of SRP-9003 and to quantify expression of β-SG in the skeletal muscle of participants with limb-girdle muscular dystrophy, type 2E/R4 (LGMD2E/R4). The study will include both ambulatory (Cohort 1) and non-ambulatory (Cohort 2) participants.

Inclusion Criteria:

• Cohort 1 only: Ambulatory per protocol specified criteria. - Cohort 2 only: Non-ambulatory per protocol specified criteria and 4 to 50 years of age.
• Possesses 1 homozygous or 2 heterozygous pathogenic and/or likely pathogenic β-sarcoglycan gene Deoxyribonucleic acid (DNA) (SGCB) gene mutations based on documented clinical findings.
• Ability to cooperate with muscle testing.

Exclusion Criteria:

• Presence of any other clinically significant illness or medical condition, including cardiac, pulmonary, hepatic, renal, hematologic, immunologic, neuromuscular (other than LGMD2E/R4), or behavioral disease, or infection or malignancy or concomitant illness or requirement for chronic drug treatment that in the opinion of the Investigator creates unnecessary risks for gene transfer or a medical condition or extenuating circumstance that, in the opinion of the Investigator, might compromise the participant's ability to comply with the protocol required testing or procedures or compromise the participant's wellbeing, safety, or clinical interpretability.
• Exposure to gene therapy, investigational medication, or other protocol-specified treatment within the protocol specified time limits.
• Any contraindication to use of corticosteroid.

Note: Other inclusion or exclusion criteria could apply.