Fighting fire with fire, researchers working with dogs have fixed a genetic glitch that causes Duchenne muscular dystrophy (DMD) by further damaging the DNA. The unusual approach, using the genome editor CRISPR, allowed a mutated gene to again make a key muscle protein. The feat—achieved for the first time in a large animal—raises hopes that such genetic surgery could one day prevent or treat this crippling and deadly disease in people. An estimated 300,000 boys around the world are currently affected by DMD.
The study monitored just four dogs for less than 2 months; more animal experiments must be done to show safety and efficacy before human trials can begin. Even so, “I can’t help but feel tremendously excited,” says Jennifer Doudna of the University of California, Berkeley, who heard the results last week at a CRISPR meeting she helped organize. “This is really an indication of where the field is heading, to deliver gene-edited molecules to the tissues that need them and have a therapeutic benefit. Obviously, we’re not there yet, but that’s the dream.”
The study, which also appears online this week in Science, was led by molecular biologist Eric Olson of the University of Texas (UT) Southwestern Medical Center in Dallas, whose team earlier had similar results in mice. “We wanted to put this to the ultimate test and see if we could do it in a large animal,” Olson says. The positive findings—CRISPR quickly restored the protein dystrophin in critical body muscles, including the heart—”brought tears to the eyes and were jaw-dropping,” he says.