Lack of association between p.Ser167Asn variant of Parkin and Parkinson's disease: a meta-analysis of 15 studies involving 2,280 cases and 2,459 controls.

Previous clinical trials have evaluated the association between Parkin p.Ser167Asn (c.601G>A) variant and Parkinson's disease (PD) risk. However, the results remain conflicting rather than conclusive. Therefore, we performed this meta-analysis to assess whether pooled results show the association. We performed structured literature searches for studies addressing the association between the Parkin p.Ser167Asn variant and PD risk. We conducted analyses of study characteristics, heterogeneity, and funnel plot asymmetry in analyses analogous to additive, dominant, recessive, and general genetic models with the odds ratio (OR) as the measure of association. When 15 eligible studies (n = 4,739 subjects) were pooled into the meta-analysis, there was no evidence for significant association in additive genetic model between Parkin p. Ser167Asn variant and PD risk (OR = 1.02, 95% confidence interval (CI) = 0.83-1.25; P = 0.866). The OR for the dominant model was 1.06 (95% CI = 0.80-1.41) while the OR for the recessive model was 0.90 (95% CI = 0.71-1.14). The OR for the heterozygous was 1.07 (95% CI = 0.80-1.43) while the OR for the homozygotes was 1.19 (95% CI = 0.81-1.74). In the subgroup analysis by ethnicity, no significant association was found in any genetic model. Begg's funnel plot and Egger's test provided visual and statistical evidences for funnel plot symmetry, suggesting no presence of publication bias. In summary, the meta-analysis strongly suggests that Parkin p. Ser167Asn variant is not associated with PD risk.