DMD is caused by a genetic mutation in the dystrophin gene. Most commonly, one or more exons (parts of the gene) are missing, causing errors in the instructions for making dystrophin, which results in the body not being able to produce enough—or any—working dystrophin protein. The goal of exon skipping, and that of Sarepta’s proprietary technologies, is to act on the RNA to allow the body to make a shorter form of the dystrophin protein to bypass the mutation.