CYP2R1 and vitamin D deficiency: In accordance to our findings, Zhu H. and colleagues revealed that participants with severe vitamin D deficiency (25(OH)D ≤25 nmol/l) showed a pattern of reduced methylation of CYP2R1, CYP24A1 and DHCR7 genes in comparison with controls (25(OH)D >75 nmol/L) [28].