Gene Therapy
Gene Transfer
The most obvious way to treat Duchnnne would be to put a new working gene into the muscle cells that will replace the one that is faulty. Many experiments in mice have shown that this can be achieved by using a modified virus, the adeno-associated virus, AAV, as a transporter or vector to transfer the active parts, the combined exons - the cDNA - of the dystrophin gene into the muscle cells. But the AAV vector is not large enough to carry the complete cDNA with all 79 exons. Only cDNAs one third as long as normal would fit in them. This means that the new dystrophin will also have only one third of its normal size. If this shortened dystrophin has one of the structures causing the benign Becker dystrophy, the effect of such a treatment would not be a complete cure but a slowing down of the fast Duchenne type dystrophy to the more benign Becker form with a practical normal life expectancy. As the newly introduced genetic material does not enter the chromosomes of the cell, the mutated dystrophin gene is not changed, it remains as it was on the short arm of the X chromosome.
Another way would be to use naked DNA or plasmids that can carry the full gene. There have been clinical trials using this method but so far without clinical benefit. Trials are planned using plasmids that can be administered under pressure to help to get them more successfully into the muscle cells.
Gene Repair
Another genetic approach, exon skipping, also does not touch the damaged gene. It only interferes with the processing of the genetic information on its way from the gene to the protein. The splicing of the exons of the premRNA to the mRNA is specifically altered so that the disrupted, out-of-frame message is made readable again, made in-frame. The result is the same as with the gene transfer technique: Duchenne dystrophy is slowed down to Becker dystrophy. A completely new type of medication, "genetic drugs", specially designed for each patient, can do this information altering: antisense oligoribonucleotides.