source: Duchenne UK
The DMD gene is made up of 79 pieces called exons. The exons link together to form a code that is read in the cells so that the protein dystrophin can be made. If there is a mutation or fault in the gene the exons no longer fit together and are not readable. The consequence is that very little or no dystrophin is made. Exon skipping drugs hide or ‘patch’ the missing piece so that the exons fit together again and can be read. A functional, although shorter, dystrophin protein is made.
Exon skipping has been shown to work in both the mdx mouse and dog models for Duchenne.
As the exon skipping drug is designed to skip over a particular exon, different versions need to be made depending on which exons needs to be skipped. The most common mutation is around exon 51 and accounts for approximately 13% of cases of Duchenne.