VDR and intervertebral disk degenerative disorder: Overall, no significant association was found between VDR FokI polymorphism and IDD risk (f vs. F: OR = 0.929, 95%CI 0.779–1.109; ff vs. FF: OR = 1.146, 95%CI 0.719–1.826; Ff/ff vs. FF: OR = 1.012, 95%CI 0.621–1.649).