Genes and Environment

Dr. William Scott and his team are advancing the study of Parkinson’s by focusing on both genetic and environmental risk factors for this catastrophic disease.  “It’s becoming increasingly clear that we might not be able to find genes without also considering environmental factors,” according to Dr. Scott.  Two recent MIHG studies, one relating to coffee and cigarette consumption, and the other to pesticide exposure, underscore this trailblazing initiative.

COFFEE AND CIGARETTES
In a study that has received national attention, MIHG researchers found that individuals genetically prone to Parkinson’s who smoke cigarettes and drink coffee are less likely to develop the disease than predisposed individuals who haven’t smoked or imbibed as much.  After analyzing the genetic variations of 356 people with Parkinson’s and 317 family members who do not have the disease, the MIHG research team determined that people who had Parkinson’s disease were 40 percent less likely to say that they had ever smoked 100 cigarettes than their unaffected family members.  The study revealed similar rates of consumption and susceptibility for coffee drinkers. 

Why is this study significant?  While previous genetic research has suggested that cigarette smoking and coffee reduces a person’s risk for Parkinson’s, this is the first study to show that cigarettes and coffee reduce risk for family members genetically prone to PD.  Investigators are now trying to figure out how environmental factors such as cigarettes and coffee influence genetic mechanisms and subsequently increase or decrease a person’s risk of developing genetic disease.  “This study improves our understanding of biology and the influence of environment on genes and disease susceptibility,” says Dr. Scott.  “We don’t know exactly what’s happening, but we know that environmental variables play a significant role in gene functioning.”  Leveraging the results from the first phase of this study, MIHG researchers are now expanding the pool of study participants to include families in South Florida.  

PESTICIDES AND PARKINSON’S
In another PD study that considers both genetic and environmental influences on heritable disease, MIHG researchers have identified possible links between Parkinson disease and exposure to pesticides.  Using a family-based study model, investigators compared members of families with PD and family members without PD.  Individuals with PD were significantly more likely to report direct pesticide exposure than relatives without the disease.

Pesticides have long been known as an environmental risk factor for Parkinson’s and one aim of this study is to figure out how pesticides influence genetic mechanisms associated with PD.  Importantly, this study shows that people may harbor specific genetic variants that are not sufficient on their own to cause PD, but exposure to pesticides might trigger genetic mechanisms and ultimately lead to sporadic cases of disease.  Scientists previously identified several genetic variations that we know contribute to PD.  However, these variations account for only a small proportion of the overall prevalence of the disease.  This study is significant in that it emphasizes the need to consider genetic and environmental interactions