ABOUT TEN YEARS ago, British veterinarians discovered an unlucky family of King Charles Spaniels whose male pups sometimes came down with a mysterious set of maladies before their first birthday. They grew clumsy and weak, and they often choked on their own tongues. To blame was a mutation on their X chromosomes, in a gene that codes for a shock-absorbing muscle protein called dystrophin. When researchers at the Royal Veterinary College realized the puppers had a canine version of the most common fatal genetic disease in children—Duchenne muscular dystrophy—they began breeding the sick spaniels with beagles to start a canine colony in the hopes of one day finding a cure.
Today, scientists report they’ve halted the progression of the disease in some of those doggy descendants using the gene editing tool known as Crispr.