August 16, 2007
UNIT 3: GeneticsControlling Parkinson’s with Gene Therapy
Genes control the production of proteins; proteins are what perform most of life’s functions. However, if a gene is mutated, the protein it codes for may not form or function properly. The mutation then causes a genetic disorder. Gene therapy is one way researchers are trying to correct mutations that cause genetic disorders, such Parkinson’s disease.
Parkinson’s disease is caused when the neurons that make dopamine, a brain chemical, fail to work or die off. The brain uses dopamine to help control movement; without enough dopamine, the brain cannot coordinate movement well. People with the disease suffer from tremors, slow movements, and stiff muscles.
Scientists are trying to help reduce the symptoms in patients with Parkinson’s disease. The researchers at the Oregon Health & Science University are testing a therapy in humans that uses a harmless virus to deliver a gene to neurons that make dopamine. The gene codes a protein that may protect the nerves from further damage and restore some of the nerve function, which should lead to improved dopamine production. The study drug, called CERE-120, is injected directly into the part of the brain where dopamine nerves are affected by Parkinson’s disease. Dr. John Nutt , director of the OHSU Parkinson Center of Oregon, says “It looks like [the gene insertion is] permanent once you get it in there.”
Hopefully, the transferred gene will restore the function of dopamine neurons that have been injured by the disease. However, the gene will not spur the brain to regrow neurons that have died already. Researchers will follow the test subjects to see if the disease symptom have changed and the quality of life has improved for the Parkinson’s patients.
While promising, gene therapy has a long way to go before it can be used to treat a large number of people. The test on Parkinson’s patients will also help scientists determine if they can deliver a gene to neurons in the brain and if they chose the right gene to help repair the neurons. "If this fails, there are two questions: Did the gene really take, or have we not selected the right gene?" Nutt said. "Maybe we didn't select the optimal gene to affect Parkinson's disease."