Parkinson sick people could soon benefit from a new, side-effects free genetic therapy that improves muscular control and eliminates the well-known tremor associated with the disease, Science Now reports.

According to the National Parkinson Foundation, Parkinson disease is a brain disorder which occurs when certain nerve cells (neurons) in a part of the brain called the substantia nigra die or become impaired. Normally, these cells produce a vital chemical known as dopamine. Dopamine allows smooth, coordinated function of the body's muscles and movement. When approximately 80% of the dopamine-producing cells are damaged, the symptoms of Parkinson disease appear.

Symptoms for the Parkinson disease include tremor (uncontrollable shaking of hands), slowness in movement, rigidity and difficulty with balance. In the United States, it is estimated that 60,000 new cases are diagnosed each year, joining the 1.5 million Americans who currently have Parkinson disease. While the condition usually develops after the age of 65, 15% of those diagnosed are under 50.

The June 23 issue of British medical journal Lancet reports that a group of researchers who sought to simply test the safety of a gene dripped into 12 patients' brains obtained more than they expected. A team led by Michael Kaplitt and Matthew During of Weill Medical College of Cornell University in New York City, joined by fellow colleagues in New Zealand, and at Neurologix, a company in Fort Lee, New Jersey, have found that the implantation of a gene called glutamic acid decarboxylase (GAD) to cells in the subthalamic nucleus (which is hyperactive in Parkinson's patients) slightly increased the overall motility in the 12 patients (11 men and a woman) who participated at the trial.

And 3 months after treatment, the patients began to improve on a test of motor function called the Unified Parkinson's Disease Rating Scale (UPDRS). The 12 patients showed an average improvement of 25% on the UPDRS after 1 year, with five improving 40% to 65%.

Despite During’s consideration that the gain in accurate motility was rather "modest," the majority of scientists consider that it is "extremely encouraging from our point of view." The majority of the patients are still doing better up to 4 years after the treatment, said During, now at Ohio State University in Columbus.