First-Ever Gene Therapy Treatment Shows Promise for Parkinson's

June 22, 2007 — -- Sufferers of Parkinson's disease, from Michael J. Fox to Muhammad Ali, may benefit from a promising but speculative weapon that could one day help doctors battle the degenerative disorder.

For the first time, scientists have used targeted gene therapy to alleviate certain symptoms of Parkinson's, such as difficulties with motor control, speech and balance.

Parkinson's disease is the second most common neurodegenerative disorder (after Alzheimer's) affecting more than 1.5 million people in the United States, most of them above the age of 65.

For now, the implications of the research, which was published in the journal Lancet Thursday, will likely be limited by the small size of the study. But the researchers involved hope that the finding may help turn the tide against the disease.

"This is a milestone for the whole field of gene therapy, and it's encouraging us to do more," said the study's lead author Dr. Michael Kaplitt at NY Presbyterian/Weill Cornell Medical Center in New York, N.Y.

The researchers injected a harmless gene-bearing virus into the brains of 11 men and one woman with moderately severe Parkinson's disease. Using viruses to get genes into people is not new; Kaplitt first used this particular virus 13 years ago.

"Viruses exist in nature mainly to transfer their own genes to the host cell," Kaplitt said in a press release issued Thursday. "So, we modify the [virus] in such a way that the only gene it carries is the one we want to deliver to the therapeutic site."

What is new is the gene that is carried into the cell, known as glutamic acid decaboxylase, or GAD. The GAD gene makes a chemical called GABA, which prevents trigger-happy neurons in the brain from firing excessively and bringing about symptoms.

"GABA is the main inhibitor in the brain," Kaplitt explained to ABCNEWS.com. The brains of Parkinson's sufferers have areas of hyperactivity, and are often lacking in GABA.

"Gene therapy would allow the brain to make its own GABA and release it to other parts of the brain."