Recent genetic studies have associated vitamin D deficiency with several candidate genes including Cytochrome P450, family 2, R, (CYP2R1), the group-specific component gene (GC) and 7-dehydrocholesterol reductase/NAD synthetase 1 (DHCR7/NADSYN1) [16]–[19]. Here, CYP2R1 is linked to vitamin D deficiency.