UT Southwestern scientists successfully employed a new type of gene therapy to treat mice with Duchenne muscular dystrophy (DMD), uniquely utilizing CRISPR-Cas9-based tools to restore a large section of the dystrophin protein that is missing in many DMD patients. DMD affects about one in five thousand males at birth and leads to progressively worsening muscle weakness in early childhood. The disease is caused by one of more than 7,000 different mutations in the gene for dystrophin – a protein that normally acts as a scaffold to support muscle fibers. Without fully functional dystrophin, the skeletal and heart muscles of people with DMD degenerate over time, eventually leading to death. The power of the method described in the study, is that you do not need a new gene editing strategy for every patient with a new mutation; you can correct multiple different mutations with a consolidated approach. This approach could lead to a treatment of DMD and inform the treatment of other inherited diseases.