The University of Rochester Medical Center researchers injected a component into mice that eliminated myotonia, a symptom which in people causes muscles to tense up and weaken, the study said.
'The significance of this work is the proof of concept that a fundamental aspect of this genetic disease can be reversed even after it is very well established,' said Charles Thornton, co-director of the university's Neuromuscular Disease Center.
'It encourages us to believe that other parts of the disease could be reversible as well,' said Thornton, the senior author of the study published in the Journal of Clinical Investigation.
But the researchers warned that more work was needed before the molecule could be tested on humans.
The synthetic compound, known as a morpholino, that was injected in the mice's muscle cells revived their chloride channel, a crucial cellular mechanism that controls electrical activity in muscles, the study said.
After the mice were injected with the compound, which the university team designed with the biotechnology company Gene Tools, the symptoms all but disappeared and did not return for several weeks.
The chloride channel is essentially disabled in humans with the disease, making it difficult for a person to relax the muscles.
For instance, a person suffering from myotonic dystrophy may be unable to release an object after grasping it.
'This work should provide hope and encouragement to people with myotonic dystrophy and their families,' Thornton said.