The results suggested no publication bias for the association of the VDR (TaqI, FokI, or ApaI) and aggrecan VNTR polymorphisms and the risk of IDD (PEgger test = 0.718, 0.128, 0.341, and 0.181, respectively) (Fig. 4). This evidence concerns the gene ACAN and intervertebral disk degenerative disorder.