https://www.scientificamerican.com/article/crispr-gene-editing-shows-promise-for-treating-a-fatal-muscle-disease1/

Duchenne muscular dystrophy is a life-threatening muscle-wasting illness. Occurring mostly in males, it is the most common type of muscular dystrophy, striking about one in 3,500 boys and causing their muscles to start breaking down in early childhood. It often confines patients to wheelchairs by the time they are teenagers and usually leads to an early death from heart or respiratory failure. There is no cure—but a genetic fix tested in dogs may offer new hope.

The disease is caused by gene mutations that make patients' muscle cells unable to produce enough dystrophin, a protein that helps muscles absorb shocks and protects them against degradation over time. In a recent study, scientists used a gene-editing technique called CRISPR/Cas9 to pump up muscle protein levels in four dogs suffering from Duchenne. The advance may hasten clinical trials for similar treatments in humans.