DMD and Duchenne muscular dystrophy: Exon skipping therapy to restore the reading frame and produce functional truncated dystrophin using antisense oligonucleotides (AOs), chemically synthesized nucleic acid analogs that specifically bind to a target exon during pre-mRNA, is promising and has already been approved for patients with DMD who have mutations in the most common hotspot in the rod domain in exons 45–55 of DMD. 13,22 In exon skipping therapy, the phenotype of the in-frame deletion in DMD must be as mild as possible, both in skeletal and cardiac muscles.