CRISPR Breakthrough Fixes Debilitating Muscular Dystrophy In Dogs

Although several treatments can alleviate some symptoms, there is currently no cure for DMD. Runa Kazakova/Shutterstock

CRISPR gene editing has just broken yet another boundary. For the first time, scientists have used CRISPR gene editing to cure dogs of the debilitating disease Duchenne muscular dystrophy (DMD), as documented in the journal Science.

DMD is a degenerative disease caused by a genetic mutation that stops the production of dystrophin, an important protein found in muscles, resulting in progressive muscle degeneration. But by carefully “snipping” out the rogue gene that stops production of the protein, researchers from the University of Texas Southwestern Medical Center were able to restore dystrophin in the muscle and heart tissue of the dogs up to 92 percent of normal levels. Dystrophin levels in the diaphragm were restored by up to 58 percent.

Considering DMD is the most common fatal genetic disease in children, there are high hopes that this technique could be used to treat humans in the not too distant future.

“Children with DMD often die either because their heart loses the strength to pump, or their diaphragm becomes too weak to breathe,” Dr Eric Olson, Director of UT Southwestern’s Hamon Center for Regenerative Science and Medicine, said in a statement. “This encouraging level of dystrophin expression would hopefully prevent that from happening.”

Dystrophin (shown in green) in a healthy diaphragm muscle (right) and the absence of dystrophin in a dog with DMD (left). UT Southwestern

People with DMD often experience severe muscle weakness, muscle wasting, and difficulty with movement. Some also have intellectual disabilities. In severe cases, the muscles that help us breathe can be so weak sufferers have to rely on assisted ventilation. It’s caused by a defective gene on the X chromosome, so most commonly occurs in boys (it can present in girls, albeit rarely) because they have only one X chromosome, so if it doesn't produce dystrophin, they don't have another to produce it.

Although several treatments can alleviate some symptoms, there is currently no cure for DMD.

“Our strategy is different from other therapeutic approaches for DMD because it edits the mutation that causes the disease and restores normal expression of the repaired dystrophin,” explained lead author Dr Leonela Amoasii. “But we have more to do before we can use this clinically.”

CRISPR-Cas9 is a relatively new technique that employs the help of a harmless virus to “cut and paste” genes out of DNA. In the simplest terms, it's a gene-editing tool that is able to modify genetic material more quickly, easily, cheaply, and precisely than ever before. CRISPR has been used on humans in a handful of clinical trials in China, however, western health authorities have been wary of making this leap.

Some more recent studies have suggested that CRISPR might not be a flawless wonder tool as it might increase the risk of cancer. That said, these were preliminary results from one study, so this is no reason to fear this revolutionary technique.

As studies like this show, it holds some truly incredible potential.

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