CYP2R1 and Obesity: VDBP is another key determinant of 25‐OH‐D levels, and polymorphisms in the GC gene (that codes for VDBP) are, along with the CYP2R1 variants, among the key genetic causes for low 25‐OH‐D.(11, 39) Lower VDBP production in the liver can result in lower 25‐OH‐D levels in plasma.(39) However, unlike CYP2R1, we did not observe any effect of obesity on the VDBP expression in mouse liver, which indicates that these two key determinants of vitamin D status are regulated differently.