Association of the COQ2 V393A Variant with Parkinson's Disease: A Case-Control Study and Meta-Analysis.

Both Parkinson's disease (PD) and multiple system atrophy (MSA) are neurodegenerative diseases of uncertain etiology, but they show similarities in their pathology and clinical course. The fact that the gene encoding α-synuclein is associated with both diseases also suggests that they share some genetic determinants. Recent studies in Japan associating MSA with a variant in the COQ2 gene led us to question whether variants in the COQ2 gene are associated with PD in Han Chinese in a case-control study. A total of 564 patients with PD were genotyped using the ligase detection rection, together with 484 gender- and age-matched healthy subjects. The M128V and R387X variants of COQ2 were not detected in patients or controls; instead, we detected only the heterozygous V393A variant (CT genotype). The frequency of the CT genotype encoding the V393A mutation was significantly higher in patients PD (4.08%) than in controls (1.86%), corresponding to an odds ratio of 2.24 (95%CI 1.03 to 4.90, p = 0.037). The frequency of the C allele of the V393A variant was significantly higher in patients with PD than in controls (OR 2.22, 95%CI 1.02 to 4.82, p = 0.039), and this was also observed in a meta-analysis of studies from mainland China, Taiwan and Japan. Subgroup analysis of our data showed that the V393A variant was significantly associated with early-onset PD (OR 3.71, 95%CI 1.51 to 9.15, p = 0.002) but not with late-onset disease (OR 1.65, 95%CI 0.69 to 3.95, p = 0.260). Gender was not significantly associated with either genotype or minor allele frequencies. In conclusion, our findings show for the first time that the V393A variant in the COQ2 gene increases risk of PD among the population of east Asia. These results, combined with research on Japanese, lend genetic support to the hypothesis that oxidative stress underlies pathogenesis of both PD and MSA.