Smoking May Affect Genetic Link to Parkinson’s Disease

HealthDay News — Smoking may modify a previously reported genetic association with Parkinson’s disease (PD), according to an analysis published online October 5 in the Annals of Neurology.

Yu-Hsuan Chuang, MPH, from the University of California, Los Angeles, and colleagues conducted a pooled analysis of the interaction between HLA-DRB1 and smoking in PD in 3 population-based case-control studies from Denmark and France involving 2,056 cases and 2,723 controls. Genotyping of the rs660895 polymorphism in the HLA-DRB1 region was based on blood or saliva DNA samples. 

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The researchers found that carrying rs660895-G (AG vs. AA: odds ratio [OR], 0.81; GG vs. AA: OR, 0.56; P=0.003) and ever smoking (OR, 0.56; P<0.001) were inversely associated with PD. There was a multiplicative interaction between rs660895 and smoking using codominant, additive (P=0.005), and dominant (P=0.001) genetic models without any heterogeneity. An inverse association of rs660895-(AG+GG) and PD in never smokers (OR, 0.64; P<0.001) disappeared among ever smokers (OR, 1; P=0.99). Similar interactions were noted when light and heavy smokers were investigated separately.

“Our study provides the first evidence that smoking modifies the previously reported inverse association of rs660895-G with PD, and suggests that smoking and HLA-DRB1 are involved in common pathways, possibly related to neuroinflammation,” conclude the authors.

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