Association between chemokine genes polymorphisms and susceptibility to Parkinson's disease: a meta-analysis and systematic review.

Objective: This study aimed to investigate the potential association between polymorphisms in monocyte chemoattractant protein-1 (MCP-1), chemokine receptor type 2 (CCR2), type 5 (CCR5), regulated on activation, normal T cell expressed, and secreted (RANTES) and susceptibility to Parkinson's disease (PD).

Methods: The MEDLINE, EMBASE, and Web of Science databases were searched for relevant articles, and a meta-analysis was conducted to assess the associations between the MCP-1 -2518 G/A, CCR2 V64I, CCR5-Δ32, RANTES - 405 G/A, -28 G/A polymorphisms and the risk of PD.

Results: Six studies with 1,416 patients with PD and 1,715 controls that met the inclusion criteria were identified. Meta-analysis of all study participants demonstrated no association between PD and the MCP-1 -2518 G allele (odds ratio [OR] = 1.089, 95% confidence interval [CI] = 0.980-1.211, p = 0.114). Stratification by ethnicity indicated no association between the MCP-1 -2518 G allele and PD in the European and Asian populations. Meta-analysis demonstrated no association between PD and the MCP-1-2518 A/G polymorphism in recessive and dominant models and homozygote contrast. However, meta-analysis revealed a significant association between the risk of PD and the CCR2-V64I AA + GG genotype in all study participants (OR = 0.418, 95% CI = 0.232-0.753, p = 0.004). Stratification based on ethnicity validated this association between the CCR2-V64I AA + GG genotype and PD in the Asian population (OR = 0.460, 95% CI = 0.243-0.870, p = 0.017), but not in European populations. Analysis using the homozygous contrast model revealed the same pattern for the CCR2-V64I AA + GG genotype. Meta-analysis revealed no association between the CCR5-Δ32 allele and the risk of PD (OR = 0.972, 95% CI = 0.377-2.501, p = 0.952). Moreover, the meta-analysis demonstrated no allelic association between RANTES - 405 G/A and - 28 G/A polymorphisms and the risk of PD.

Conclusions: Our meta-analysis showed that the CCR2 V64I polymorphism is associated with PD, especially in Asian populations.