Genetic Engineering for Parkinson's Disease

On the forefront of potential treatments, genetic engineering holds promise for changing the future treatment of Parkinson's disease.

Introducing Genetic Engineering

• Genetic engineering is the science of gene modification, a science that researchers have tried to take advantage of for years to find the all-elusive causes for particular diseases such as Parkinson's. Since a person's DNA acts as the "blueprint" of life, often determining which illnesses and characteristics they will have, research to "decode" the sequence could help to find the root cause of the beginning of disease. Researchers have hypothesized that since each individual has a gene sequence, finding the specific gene sequence that accompanies each of the diseases should be the logical key to understanding the exact makeup of mutations and then specifically identifying treatment for those particular gene sequences. Gene therapy—in which functional sequences replace the defective sequences—could follow.

Finding the Cause

• Genome-Wide Association Studies are studies that search for common threads in genome sequences, and they have started to reveal promising results. A study conducted across Europe and Japan concluded that there are two sequences strongly associated with Parkinson's disease, which researcher's consider confirmation that common causation exists. Until recent years, the cause of Parkinson's disease has been elusive. The controversial hypothesis that defective genes cause the disease is joined by the hypothesis that environmental toxins or oxidative stress may cause the deterioration of neurons responsible for the symptoms of Parkinson's. Determining the etiology of the disease is urgent for those affected, since disease progression can cause everything from tremors and rigid muscles to dementia and the loss of automatic movements.

Potential for Therapy

• The tremors and rigidity seen in Parkinson's come about when something called L-dopa doesn't have time to turn into dopamine. Instead, the L-dopa can become norepinephrine or epinephrine when L-dopa is not able to reach the brain. When not enough dopamine is present, too much activity in the movement-regulating subthalamic nucleus causes patients to be unable to regulate their movement.

Latest Progress

• On the forefront of genetic engineering is a therapy called AAV gene transfer technology, in which the non-disease-causing AAV virus is inserted into the genes. Clincial studies have begun to reveal that a specific vector called glutamic acid decarboxylase causes increased levels of GABA in the brain. GABA is beneficial as an inhibitory neurotransmitter, which keeps L-dopa from being converted before it can become dopamine in the brain.

The Future

• Genetic engineering may provide the opportunity to shape our genetic tendencies, but responsibility comes with it. Previous attempts at genetic engineering have been speckled with unintended consequences, just as could occur with the treatment of Parkinson's disease. Issues may arrive if the immune system rejects the implanted genes, or the intervention could be ineffective if the disease requires that multiple parts of the genetic sequence be treated.

  Scientists must be careful to ensure that certain gene sequences are actually causing Parkinson's. Some geneticists think there may be more meaningless statistical variation than actual causation taking place during some of the genome association studies.