Parkinson's disease gene therapy trial begins

A US man affected by Parkinson's disease became the first patient to receive experimental gene therapy treatment for his illness last week. Fifty-five year-old Nathan Klein is one of 12 people enrolled on a new trial taking place at New-York Presbyterian Hospital, in which doctors will inject a therapeutic gene into the patient's brain in a effort to halt the progression of the disease. The US Food and Drug Administration granted permission for the trial to go ahead last year, after the US and New Zealand team published results that showed the technique worked in rats.

The team, lead by neurosurgeon Michael Kaplitt, first cut through Klein's skull to gain access to the region of the brain that controls movement. The symptoms of Parkinson's disease - uncontrollable shaking, rigidity of the limbs, slowness of movement and impaired balance and coordination - are caused by a gradual loss of dopamine-producing brain cells in this area of the brain.

Existing treatments for Parkinson's disease involve replacing the dopamine, a chemical that controls brain activity. But in the new trial, the doctors did not want to target dopamine production directly, as they thought many patients might already be resistant to its effects. Instead, the team injected a gene called GAD into Klein's brain, which should in turn trigger production of a protein called GABA (Gamma-Aminobutyric acid). It is hoped that this brain chemical will then 'quiet' the overactivity of the brain that causes the unwanted body movements. 'Dopamine is like the key to the car. But if you hotwire the car, you don't need the key' said Kaplitt.

Kaplitt stresses that the trial is primarily to assess the safety of the approach: 'My goal is not to try to cure Parkinson's disease' he said. 'It's to provide a better treatment that we can build on to make the next advance'.