Such robust skipping in the heart, likely related, in part, to tropism of AAV9 for that organ, will be of clinical relevance in treating boys with DMD, as cardiomyopathy is a significant cause of morbidity and mortality.46 We have not tried to assign a therapeutic degree of skipping in this WT DMD context, as unpublished data from the preclinical development program demonstrate a higher degree of exon 2 skipping in the Dup2 context in comparison with the WT context. Here, DMD is linked to Duchenne muscular dystrophy.