"When a particular chemical imbalance in the muscle tissue was restored, it eliminated stiffness," Thornton said. "This would be a partial solution to the person's symptoms with myotonic dystrophy, but it's also proof of principle that once we identify the cause that it can be corrected."
Considerably more work is needed, however.
For one thing, scientists need to find a way to inject the compound into a person's bloodstream so a systemic effect would take place. Injecting into muscles spurs only a local effect. "That's one obstacle that must be overcome in getting wide distribution," Thornton said.
Safety issues also have to be considered before human trials begin, Cwik added.
"They are only looking at one symptom of myotonic dystrophy," she noted. "Would this therapy or kind of therapy, which can reverse or eliminate myotonia, have any effect on some of the other potentially more disabling symptoms? While it's encouraging, there are a lot of cautions and caveats."
There's more on myotonic dystrophy at the Muscular Dystrophy Association.
SOURCES: Charles A. Thornton, M.D., professor, neurology, University of Rochester School of Medicine and Dentistry; Valerie Cwik, M.D., medical director and vice president, research, Muscular Dystrophy Association; Nov. 15, 2007, Journal of Clinical Investigation