Gene Editing For Duchenne Muscular Dystrophy Shows Promise
There is no treatment for Duchenne muscular dystrophy. It’s a rare and fatal genetic condition that progressively weakens all muscles, including the heart. But scientists from UT Southwestern Medical Center have successfully used a gene editing tool to halt the disease in young mice.
When most little boys were running up and down stairs, Ben Dupree was using his arms to pull himself up the wood banister in his home in University Park. His mom, Debbie, knew something was wrong.
“I can remember any step he would take, being worried that he was going to fall,” she said.
Ben was 9 when he was diagnosed with Duchenne muscular dystrophy. Like an estimated one in 3,500 boys, his muscles were beginning to weaken, starting with the hips and thighs.
For a while, Ben continued to walk. But when he was 15, he slipped — and he decided it was time for a wheelchair.
“I kind of was almost in denial,” Ben said. “Ignoring it, pushing it off for awhile.”
Doctors told Debbie Dupree that Ben would be dead by the time he was 19. For many boys with Duchenne, that’s the reality.
But today, Ben is 23 years old. He’s a recent graduate of Southern Methodist University. Ben’s success in slowing down the disease is partly thanks to genetic luck, and support from people like his mom.
“We have spent a lot of time, and a lot of expense, going to additional therapies to keep him in the shape that he’s in,” she said. She helps her son with everything from stretching and managing medication to doctors’ appointments. She also works with the nonprofit Parent Project Muscular Dystrophy.
“The emotional impact of this on him and our family and other families with muscular dystrophy is huge,” Dupree said.
Over the years, there have been many attempts to find cures for the fatal disease, but so far, Dr. Eric Olson says nothing has worked.
“While some of the approaches that have been taken provided some short term benefit for these boys, ultimately, they inevitably succumb to the disease if they have a mutation in the dystrophin gene,” Olson says.
Olson is chairman of molecular biology at UT Southwestern and co-director of the school’s new Wellstone Muscular Dystrophy Cooperative Research Center. His latest research is shaking up the Duchenne muscular dystrophy community. Why? Well, he’s figured out how to use a new gene editing tool to correct the mutation that causes the disease in mice.
“It’s really amazing,” Olson said. “Because what it allows you to go into the DNA sequence of the body and with absolute precision to change even a single letter in the DNA code that may have a mutation and eliminate that mutation permanently.”
The gene editing tool is called CRISPR/Cas9.
To understand how it works, imagine a big banner in the sky; it’s supposed to say, “Congratulations” but instead reads “Clongratulations.” You have to figure out a way to reach the banner, then cut out that extra letter “L.”
That’s essentially what this high-tech pair of gene editing scissors makes possible.
Granted, instead of editing a banner, we’re talking about editing a gene about the size of a mustard seed. And instead of doing it in humans, Olson’s team did it in mice. Still, researchers say it is an impressive advance.
Gang Bao, a bioengineering professor at Rice University, says the possibility of using gene editing to treat diseases like Duchenne muscular dystrophy or Huntington’s is exciting. Imagine a single injection correcting muscles in the body, including the heart. A major challenge, Bao says, is keeping the Nano scissors from cutting what they’re not supposed to cut.
“They may cut at the location you want them to cut, but they may also cut at other locations. Those could cause a disease, so the potential is there,” Bao said.
As researchers work to refine the technique, and prepare for human trials, young men like Ben Dupree are cheering from the sidelines.
“I would like to see a stop in my decline,” Ben said. “Which I think is probable with [gene editing], but it may not be in the near future.”
Ben’s near future is promising. He’s just applied for a master’s degree and wants to be a genetic counselor.
“My original excitement about genetics was all due to wanting to understand my condition,” he said. “I found that I really enjoyed more of the human element, talking with people, explaining what muscular dystrophy is, how the genetics is involved and wanting to be in a position where I can help other people with Duchenne manage and understand the condition.”