Smoking has been reported to be inversely associated with Parkinson's disease (PD) in many studies, but a recent study in China found that smoking increased the risk of PD. Variants in genes associated with dopamine metabolism found to increase the risk for PD have also been associated with smoking behavior. To investigate the association between smoking and PD in a Chinese population and determine whether the genetic variants of genes involved in dopamine metabolism influence the relationship between smoking and risk for PD. Chinese PD patients were recruited from Xuanwu Hospital. Controls were sampled from community. Detailed information on life-long smoking behavior was collected by face-to-face interview. Genotypes were determined for SLC6A3 VNTR, COMT Val108/158Met and MAO-B intron13 A/G polymorphisms by PCR-RFLP, DHPLC and sequencing. Chi-square and logistic regression model were used in the analysis. 176 PD cases and 354 controls were enrolled in this study. 23.9% cases are smokers, compared to 48.0% in controls. Ever smoking is inversely associated with PD (odds ratio=0.14, 95% CI 0.08-0.26, adjusted for age and gender). None of the above-mentioned genetic polymorphisms was associated with PD risk or smoking. When each variant was included in the logistic regression model, the inverse association between smoking and PD remained the same, and the interactions between smoking and variants were not significant in the model. Our data support a reduction of PD risk associated with smoking in a Chinese population. These variants of genes associated with DA uptake and metabolism do not affect the inverse association between smoking and PD.
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