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Similarities Between Genetic and Non-Genetic PD May Aid Research
- Oct 29 2013
People with a rare genetic form of Parkinson’s disease (PD) have similar symptoms as people with non-genetic PD, according to the October 15 online issue of Movement Disorders. The study found a few exceptions in which those with genetic-PD, who were of Ashkenazi Jewish descent and each had a mutation in the LRRK2 gene, differed from their peers; for example they had a tendency to first experience symptoms in the lower body. But overall, the study highlighted similarities between the two forms of PD, which may help research moving forward.
A small percentage of people with Parkinson’s develop the disease due strictly to genetics, and the most common gene implicated is LRRK2. Among people with PD who are of Ashkenazi Jewish descent, about 15-18 percent carry a LRRK2 mutation known as G2019S. As this mutation and others are identified, researchers try to explore whether these mutations explain one’s PD risk, symptoms and progression.
A consortium of researchers in New York, NY, and Tel Aviv, Israel, was established in 2009 to investigate the G2019S mutation. For this study, researchers led by Roy N. Alcalay, M.D., at the PDF Research Center at Columbia University Medical Center, recruited 488 study participants who had PD and had at least two Ashkenazi Jewish grandparents. They screened all participants for LRRK2 G2019S mutations. In addition, using standard tests, rating scales and questionnaires, they put together a detailed picture of each participant’s experience with Parkinson’s disease.
- Of the 488 participants, 20 percent carried the LRRK2 G2019S mutation.
- Overall, carriers reported a similar experience with Parkinson's disease as non-carriers.
- 52 percent of the carriers were women, compared to the general population in which men are more likely to develop Parkinson’s disease.
- 40 percent of carriers reported first PD symptoms in their lower extremities while 19 percent of non-carriers reported the same.
- Carriers were more likely to have walking and balance problems than non-carriers.
- Carriers who experienced balance problems did not experience cognitive impairment, yet non-carriers frequently experienced the two symptoms together.
- Carriers had a good response to levodopa therapy even after five years.
What Does it Mean?
Parkinson’s disease can vary greatly from one person to another, making it difficult for doctors to provide people with PD with accurate prognosis. Researchers have looked to genes to explore whether one’s genetic background may explain PD progression.
This study found that people who develop PD from the G2019S mutation in the LRRK2 gene experience Parkinson’s disease very similarly as do people with non-genetic PD, with a few exceptions. For example, carriers were more likely to be women than non-carriers, more likely to have symptoms in their legs and affecting their gait, but were less likely to have tremor.
Overall, the similarities between the two groups are very encouraging for research. With this knowledge, researchers can now use a genetic model of LRRK2 as a way to better understand all forms (genetic and non-genetic) of PD.
This study is the first study published from this group of study participants. Additional studies (e.g., comparing cognitive performance) are expected in the future.
Reference: Alcalay, R. N., Mirelman, A., Saunders-Pullman, R., Tang, M.-X., Mejia Santana, H., Raymond, D., Roos, E., Orbe-Reilly, M., Gurevich, T., Bar Shira, A., Gana Weisz, M., Yasinovsky, K., Zalis, M., Thaler, A., Deik, A., Barrett, M. J., Cabassa, J., Groves, M., Hunt, A. L., Lubarr, N., San Luciano, M., Miravite, J., Palmese, C., Sachdev, R., Sarva, H., Severt, L., Shanker, V., Swan, M. C., Soto-Valencia, J., Johannes, B., Ortega, R., Fahn, S., Cote, L., Waters, C., Mazzoni, P., Ford, B., Louis, E., Levy, O., Rosado, L., Ruiz, D., Dorovski, T., Pauciulo, M., Nichols, W., Orr-Urtreger, A., Ozelius, L., Clark, L., Giladi, N., Bressman, S. and Marder, K. S. (2013), Parkinson disease phenotype in Ashkenazi jews with and without LRRK2 G2019S mutations. Mov. Disord. doi: 10.1002/mds.25647 http://dx.doi.org/10.1002/mds.25647
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Source Date: Oct 29 2013