Researchers identify differing risk factors contributing to Parkinson's Disease in men and women

ROCHESTER, Minn. -- New Mayo Clinic research provides evidence that environmental factors may play a greater role in the development of Parkinson's disease in men, while for women, hereditary factors may play a greater role. The findings, to be published in the journal Movement Disorders, will be available Wednesday for early viewing online at http://www.interscience.wiley.com/jpages/0885-3185/.
The investigators performed an innovative two-step statistical analysis to study Parkinson's disease risk factors. They found that complex interactions between common gene variants contribute to Parkinson's disease risk in women.

The researchers postulate that environmental exposures often are sufficient to lead to Parkinson's disease risk in men.

"For women, genetic predisposition may be more important because they are less exposed to environmental risk factors linked to Parkinson's disease in previous research. Also, estrogen may protect women's brains from the effects of these environmental factors...

"The causes of Parkinson's disease differ between men and women," says Dr. Maraganore. "Traditionally, men have been out in the workforce becoming exposed to environmental risk factors such as pesticides and industrial chemicals or suffering head injuries.

By contrast, women have been less exposed to these factors and require a stronger genetic susceptibility to develop Parkinson's.

Furthermore, estrogen, the main sex hormone in women, reduces the risk of developing the disease.

"For a woman to get Parkinson's disease, she has to inherit certain gene variants," says Dr. Maraganore. Hormonal factors combined with more limited environmental exposure may help protect women from Parkinson's disease.

In this study, Mayo Clinic researchers discovered an interaction between common variants of two genes -- ubiquitin carboxy-terminal hydrolase L1 (UCHL1) and a-synuclein -- that leads to a significantly higher risk of Parkinson's disease than commonly occurs in the population. Rare mutations in these two genes as well as in a gene called "parkin" also have been shown to cause rare inherited forms of Parkinson's disease.

The Mayo Clinic researchers performed genetic tests on blood samples from 319 unrelated Parkinson's disease cases and 196 cases with no evidence of Parkinson's disease...

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