A systematic review and meta-analysis of the associations of vitamin D receptor genetic variants with two types of most common neurodegenerative disorders

Background Whether vitamin D receptor ( VDR ) genetic variants influence individual susceptibility to neurodegenerative disorders remains controversial. Aims This meta-analysis was conducted to analyze correlations of VDR genetic variants with two types of most common neurodegenerative disorders, Parkinson’s disease (PD) and Alzheimer’s disease (AD). Methods Systematic literature research of PubMed and Embase was performed to identify eligible articles. Q test and I 2 statistic were employed to decide whether pooled analyses would be performed with random-effect models (REMs) or fixed-effect models (FEMs). All statistical analyses were conducted with Review Manager. Results Totally sixteen studies were enrolled for analyses. Among these eligible studies, ten studies were about PD (2356 cases and 2815 controls) and six studies were about AD (1256 cases and 1205 controls). Pooled overall analyses suggested that VDR rs7975232 (additive model: p = 0.03, OR = 1.19, 95% CI 1.01–1.39) and rs2228570 (recessive model: p < 0.008, OR = 1.26, 95% CI 1.06–1.50; allele model: p < 0.001, OR = 0.80, 95% CI 0.71–0.91) variants were significantly correlated with PD, and VDR rs731236 (dominant model: p = 0.003, OR = 0.70, 95% CI 0.56–0.89; additive model: p = 0.02, OR = 1.32, 95% CI 1.06–1.66; allele model: p = 0.02, OR = 0.82, 95% CI 0.69–0.96) variant was significantly correlated with AD. Further subgroup analyses by ethnicity revealed that the positive results were mainly driven by the Asians, whereas no significant associations were observed in Caucasians. Conclusion Our meta-analysis suggested that VDR rs7975232 and rs2228570 variants might serve as genetic biomarkers of PD, whereas VDR rs731236 variant might serve as a genetic biomarker of AD.