Duchenne muscular dystrophy (DMD) is the most common, yet severe, form of muscular dystrophy, a group of rare neuromuscular disorders.  DMD is caused by mutations in the gene that codes for a protein called dystrophin. This protein is needed in order for muscles to function properly. The disease primarily affects boys, who usually lose their ability to walk by the time they are twelve years old. DMD is fatal and most people with it live to twenty and forty years of age. So far, there’s no cure but various animal studies have shown promise in gene editing of DMD. There are also various treatments available.

A recent article presented by Yahoo Finance describes the gene editing efforts of Vertex Pharmaceuticals in partnership with CRISPR Therapeutics, working towards treatment of DMD. The researchers approach to gene editing involves correcting mutations that lead to disease. In other words, editing pieces of DNA at the target area along the gene.

In the case of the dystrophin gene, this is a problem because of its size. It’s the longest of all human genes. Only one percent of the gene is responsible for creating dystrophin. However, the critical part is separated into eighty-nine segments spaced along the length of the gene.

Vertex and CRISPR searched for a method of dealing with the dystrophin gene and found the answer in Exonics Therapeutics. Exonics had used CRISPR successfully in the repair and restoration of dystrophin in animal models.

Vertex has taken on another muscle-wasting disease by licensing the rights of its developer. The disease is called myotonic dystrophy Type 1. It is characterized by three nucleotides (molecules) in a continuous sequence that affects a gene critical to muscle activity.

About Gene Therapy

Gene therapy is an area of therapeutic development that uses genetic material to treat a disease. Although it has been studied since 1989, gene therapy treatments were only approved recently by the FDA for use in humans outside of clinical studies. One therapy known as micro-dystrophin is now licensed by Sarepta Therapeutics. It is one of the most advanced treatments in this expanding field.

In gene replacement therapy, scientists begin by creating a new copy of the missing gene in a laboratory. A noninfectious virus, usually the AAV virus, is selected to carry the gene to the nucleus, or control center of the cell. From there, the gene sends out instructions to manufacture the protein that is missing or in short supply.

A recent clinical trial readout from Sarepta reported that its micro-dystrophin was successful in allowing the dystrophin complex to function normally and that muscles were protected from deteriorating at each movement.

Both gene editing and gene therapy are currently being studied in clinical trials but only gene therapy has received FDA approval as a treatment mechanism. It is evident that both have their advantages but it remains to be seen which of the two treatments will be most effective for DMD.

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