Parkinson's Disease

Parkinson’s is a neurodegenerative disease that appears when certain nerve cells of the brain, in a region called the substantia nigra, die or become impaired. These nerve cells are responsible for producing dopamine, which enables smooth, coordinated muscular motions throughout the body. The disease was originally called "the shaking palsy" and identified in 1817 by British Dr. James Parkinson, after whom it is now named.

Symptoms of Parkinson’s appear after about 80% of the dopamine-producing nerve cells cease to function properly. The symptoms include tremors, slowness of movement, difficulty balancing, and rigid or stiff movements and may result in cramped handwriting, shuffling feet while walking, muffled speech, rigid facial expressions and depression. Parkinson’s affects men and women equally, and usually those over the age of 65. Over 60,000 cases are diagnosed each year in the United States.

There are no known cures for Parkinson's, but some treatments can slow progression of the disease and help alleviate the symptoms. The treatments usually involve replacement of the missing dopamine, and drugs for this disease often contain L-dopa, the intermediate precursor in the production of dopamine from the amino acid tryptophan. Other drugs might be used to inhibit neurotransmittors or suppress MAO-B, the enzyme that degrades dopamine. Certain surgical procedures can be used to alleviate symptoms in extreme cases. Although these medications can greatly improve quality of life, many individuals are able to live and manage their disease without medication.

A number of genes have been linked to Parkinson’s disease:

• Alpha-synuclein
• Parkin
• Ubiquitin carboxyl-terminal hydrolase
• DJ-1
• SCA2
• GIGYF2

The discovery of GIGYF2 has only just been reported (as of March 2008). More is known about the first 5 genes which each play a role in abnormal protein processing in cells. For example, in cells, proteins that have been coated with ubiquitin are marked for distruction. Mutations in the genes for ubiquitin carboxyl-terminal hydrolase or parkin, result in certain proteins not being ubiquitinated and, therefore, not destroyed. This can cause harm and cell death when the proteins accumulate in cells.

Use of glial-derived neutrophic factor is a theraputic treatment that has shown some success at protecting dopamine-releasing neurons. A gene therapy technique using stem cells, known as therapeutic cloning, has also shown some promise, as has a treatment in which dopamine-producing enzymes in the brain are replenished using a viral vector that delivers the gene for the enzyme to the brain.

_Sources:

National Parkinson Foundation website: www.parkinson.org/NETCOMMUNITY/Page.aspx?pid=201&srcid=-2

Parkinsons.org website: www.parkinsons.org