CYP2R1 and vitamin D deficiency: Genetic deletion of CYP2R1 resulted in severe symptoms of vitamin D deficiency in mice, including hypocalcemia, hyperphosphatemia, and osteomalacia (Roizen et al., 2018), and a multicenter genetic association study revealed that a few CYP2R1 genetic polymorphisms were correlated with serum 25(OH)D3 level to varying degrees (Wang et al., 2010).