The role of vitamin D metabolic pathway gene methylation in the development of human disease had been studied, and Wang et al. suggested that the methylation levels of the CYP24A1, CYP27A1, CYP27B1, CYP2R1, and VDR genes were associated with the risk and prognosis of tuberculosis (19). The gene discussed is CYP27A1; the disease is tuberculosis.