scientists say they've conducted the first gene therapy trial for a form of muscular dystrophy that disables by weakening hip and shoulder muscles.

Researchers from the University of Florida, Nationwide Children's Hospital in Columbus, Ohio, and Ohio State University said they safely transferred a gene to produce a protein necessary for healthy muscle fiber growth into three teenagers with limb-girdle muscular dystrophy.

"We think this is an important milestone in establishing the successful use of gene therapy in muscular dystrophy," said Dr. Jerry Mendell, lead author of the study. "This trial sets the stage for moving forward with treatment for this group of diseases and we are very pleased with these promising initial results.

"In subsequent steps we plan to deliver the gene through the circulation in hopes of reaching multiple muscles. We also want to extend the trials over longer time periods to be sure of the body's reaction," said Mendell.

Limb-girdle muscular dystrophy actually describes more than 19 disorders that occur because patients have a faulty alpha-sarcoglycan gene. In each of the disorders, the muscle fails to produce a protein essential for muscle fibers to thrive. It can occur in children or adults.

The study's findings are to appear in the journal Annals of Neurology.