Genome engineering: a new approach to gene therapy for neuromuscular disorders

For many neuromuscular disorders, including Duchenne muscular dystrophy, spinal muscular atrophy and myotonic dystrophy, the genetic causes are well known. Gene therapy holds promise for the treatment of these monogenic neuromuscular diseases, and many such therapies have made substantial strides toward clinical translation. Recently, genome engineering tools, including targeted gene editing and gene regulation, have become available to correct the underlying genetic mutations that cause these diseases. In particular, meganucleases, zinc finger nucleases, TALENs, and the CRISPR-Cas9 system have been harnessed to make targeted and specific modifications to the genome. However, for most gene therapy applications, including genome engineering, gene delivery remains the primary hurdle to clinical translation. In preclinical models, genome engineering tools have been delivered via gene-modified cells or by non-viral or viral vectors to correct a diverse array of genetic diseases. In light of the positive results of these studies, genome engineering therapies are being enthusiastically explored for several genetic neuromuscular disorders. This Review summarizes the genome engineering strategies that are currently under preclinical evaluation for the treatment of degenerative neuromuscular disorders, with a focus on the molecular tools that show the greatest potential for clinical translation of these therapies.