In contrast, Exondys51, Vyondys53, Vitolarsen and Amondys45 are phosphorodiamidate morpholino oligomers (PMO) that target the DMD pre-mRNA to exclude exon 51, 53 (Vyondys and Vitolarsen) or 45, respectively, in order to re-frame the dystrophin transcript around frame shifting deletions flanking the respective exons, as a treatment for Duchenne muscular dystrophy (Mendell et al., 2013; Clemens et al., 2020; Frank et al., 2020; Shirley, 2021). Here, DMD is linked to Duchenne muscular dystrophy.