Becker Muscular Dystrophy - A Natural History Study to Predict Efficacy of Exon Skipping

We will utilize the Cooperative International Neuromuscular Research group (CINRG) network to
collect cohorts of Becker muscular dystrophy (BMD) patients with in-frame deletions in the
dystrophin gene. We will collect clinical data across multiple body systems and correlate
these findings to the high-resolution deletion break-point mapping performed from the tissue
samples. We will investigate the observed variability to deepen our understanding of
molecular mechanisms relevant to the optimization of exon skipping therapeutic approaches.

Inclusion Criteria:

- Male

- Age 4 or older

- Diagnosis of BMD with an in-frame deletion in the dystrophin gene, where the
boundaries of the mutations are confirmed.

Exclusion Criteria:

• Investigator assessment of inability to comply with protocol