Figure 1.

Antisense oligonucleotide (ASO)-mediated exon-skipping therapy.

In DMD, an out-of-frame exon is deleted from the pre-mRNA (dotted box at the top). Therefore, the splicing produces an out-of-frame mRNA (middle) and no dystrophin (bottom). An ASO induces the skipping of the flanking exon to the deleted exon (red box) during splicing and produces an in-frame mRNA (middle), and the in-frame mRNA produces semifunctional dystrophin (bottom). The black boxes and lines indicate exons and introns, respectively.