VDR and Alzheimer disease: Six articles with 1,031 cases and 1,112 controls explored correlation between VDR FokI polymorphism and the AD risk, five studies with 494 cases and 622 controls detected correlation between VDR BsmI polymorphism and the AD risk, seven studies with 816 cases and 991 controls examined relationship between VDR TaqI polymorphism and the AD risk, and five literatures involving 685 cases and 879 controls investigated association between VDR ApaI polymorphism and the AD risk.