VDR and osteoporosis: We got 506 articles by searching, according to the inclusion and exclusion criteria, 43 studies met our requirements (involving 4680 osteoporosis cases and 5373 controls) [21,22,40–80], of which 34 studies explored the association between VDR BsmI and osteoporosis risk (involving 2973 osteoporosis cases and 3724 controls), 19 studies reported VDR FokI (involving 3694 osteoporosis cases and 2943 controls), and 4 studies explored VDR Cdx2 (involving 378 osteoporosis cases and 743 controls).