Chapel Hill, N.C. — Researchers at University of North Carolina at Chapel Hill have gotten a glimpse into what happens in patients suffering from Duchenne Muscular Dystrophy, the most common and severe form of the disease.

Duchenne occurs when the X chromosome fails to make a key muscle protein. The best medical therapy can only slow the progression of muscle weakness.

About 10 years ago, researchers at UNC began looking at a way to replace a genetic defect in patients with the disease. It involves the protein dystrophin, which helps stabilize muscle cells.

“If the dystrophin is missing, then the muscle cells become very fragile, very unstable. It gets damaged all the time,” said Xiao Xiao, a UNC professor in gene therapy.

Xiao engineered a mini-gene, carried by a dead-virus, injected into the muscle of animal models – to correct the genetic defect.

Positive results led to human trials in Ohio, where investigators discovered that some patients had an immune response against the protein. It was a closed door that opened other doors, said study author R. Jude Samulski, director of UNC's Gene Therapy Center.

“We finally got a glimpse of what happens in a patient. That information let's us go back to the lab and redesign our tools to come back to address this disorder in a positive manner,” Samulski said.

Researchers said one new strategy might be to find a way to bypass the immune system to replace the defective gene using the therapy designed at UNC. The concept isn't new. There are already anti-rejection medications used to help transplant patients' immune system accept a donor organ.

UNC researchers said their discovery could also be applied to some other genetic disorders.

The study is published in the New England Journal of Medicine.