We finally have some very promising news for the development of adequate treatment for our boys with mutations requiring double or multi exon skipping!
In reading through this article about injecting a fully functional version of the dystrophin gene into the body using a harmless virus, it doesn't mention anything about applicability of multi-exon skipping for DMD mutations in order to restore the open reading frame. However, in a recent interview with PPMD, Dr. Duan indicated that the CRISPR/Cas9 gene therapy that they've seen success with in dogs would also be successful for those DMD patients with a deletion of exons 46-50, and, indeed, other multi-exon mutations as well. (Go to page 13 for more details.)
Dr. Duan references this paper about the CRISPR/Cas9 technology:
Included in that link is the following that I wanted to draw your attention to. For our boys, "D" is the key: