An updated analysis with 45,078 subjects confirms the association between SNCA rs11931074 and Parkinson's disease

Interaction between SNCA gene polymorphisms and T2DM with Parkinson's disease

AIMS

To investigate the association of several single nucleotide polymorphisms (SNPs) within alpha-synuclein (SNCA) gene and additional gene-environment interaction with Parkinson's disease (PD) risk.

METHODS

Hardy-Weinberg equilibrium (HWE) is tested for controls using SNPstats (http://bioinfo.iconcologia.net/SNPstats). Logistic regression is used to calculate the ORs (95% CI) for relations between the four SNPs and PD risk. The generalized multifactor dimensionality reduction (GMDR) model is used to evaluate the synergy between gene and environment.

RESULTS

A total of 1161 people were included in this study, including 386 cases of PD and 775 normal controls. In this study, the genotype frequency of the control group was consistent with HWE distribution. Rs356219-G allele frequency was 30.0% in patients and 19.8% in control group. The rs356221-T allele frequency was 29.7% in the patients and 20.8% in the control group. Rs356219-G and rs356221-T alleles were associated with increased PD risk, with adjusted ORs (95% CI) of 1.92 (1.28-2.52) and 1.52 (1.05-2.02), respectively. We also found no significant correlation between rs2301134 and rs2301135 and susceptibility to PD. The best gene-environment interaction models were determined by GMDR analysis, which shown a significant gene-T2DM interaction combinations, but the gene-alcohol drinking interaction combinations were all not significant. We also conducted stratified analysis for interaction effect using logistic regression. We found that T2DM patients with rs356221-AT/ TT genotype have the highest PD risk, compared to subjects with rs356219-AA genotype, OR (95%CI) = 2.67 (1.83-3.46).

CONCLUSIONS

The rs356219-G and rs356221-T, gene-environment interaction between rs356221 and T2DM were all associated with increased PD risk.

Association between alpha-synuclein (SNCA) rs11931074 variability and susceptibility to Parkinson's disease: an updated meta-analysis of 41,811 patients

BACKGROUND AND OBJECTIVES

Parkinson's disease (PD) is one of the most common forms of neurodegenerative disorders, and its etiology remains unclear. Single nucleotide polymorphisms (SNPs) of alpha-synuclein (SNCA) have been found to be significantly associated with PD risk. In particular, the variant rs11931074 was found in one meta-analysis to appear to play a role in the occurrence of PD. This finding has been questioned in subsequent studies, however. The aim of this study was to determine the relationship between PD risk and rs11931074 polymorphism.

METHODS

We performed a systematic online search, including PubMed, Web of Science, EMBASE, Cochrane Library, and CNKI (China National Knowledge Infrastructure), aiming to identify case-control studies looking at the role of rs11931074 in PD. We performed calculations of pooled odds ratio (OR) and 95% confidence interval (95% CI) to assess the associations, and subgroup meta-analyses to verify differences between various ethnicities of different study populations.

RESULTS

A total of 13 studies involving 13,403 cases and 28,408 controls met the inclusion criteria after assessment by two reviewers. Overall, there exists significant associations between SNCA rs11931074 polymorphism and the risk of PD under five genetic models (allele contrast model: T vs. G, OR = 1.28, 95% CI = 1.12-1.45, P = 0.0001; homozygote model: TG vs. GG, OR = 1.55, 95% CI = 1.17-2.05, P = 0.002; heterozygote model (TT vs. GG, OR = 1.23, 95% CI = 1.05-1.42, P = 0.009; dominant model: TG+TT vs. GG: OR = 1.25, 95% CI = 1.05-1.50, P = 0.01 and recessive model: TT vs. TG+GG: OR = 1.40, 95% CI = 1.18-1.68, P = 0.0002). When ethnicities were stratified, significant associations were found in the allelic, homozygote, and recessive models for Asians, and in the allelic model for Caucasians.

CONCLUSION

SNCA rs11931074 polymorphism is found to be associated with PD risk and this risk appears to be influenced by genetic status and ethnicity.