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What is Exon Skipping?

Exon skipping is a strategy for making a shortened, but partially functional version of the dystrophin protein. Typically, it is for individuals who have a deletion mutation, which is the most common type of mutation found in 60-70% of individuals with Duchenne. 

The gene for the dystrophin protein is made up of segments called exons. Some of the segments fit together nicely, while others are not able to. 

Image depicting exons as puzzle pieces from one to seventy-nine

The idea of exon skipping is to block the inclusion of exons that prevent the existing exons from fitting together. In the example below, there is a deletion mutation of exons 48-50. 

Image depicting example of exon skipping

Exons 47 and 51 cannot fit together. To make it so that the two ends of the gene can fit together, you can exclude exon 51. 

Image depicting the product of exon skipping - resulting in a fully functional protein

A protein that is missing exons 48-51 would not work as well as a full protein, but it would still do the job it is supposed to. Typically, Becker patients have mutations where parts of the protein are missing but they can still fit together. So, we expect exon skipping drugs to result in a progression of disease more similar to Becker muscular dystrophy.  

Click here to learn more about exon skipping drugs currently approve or under investigation.