Therefore, the main aims of the present study are (i) to evaluate the associations between vitamin D levels and clinical outcomes and lipid profile in RA patients depending on their genetic status of VDR (rs2228570), CYP27A1 (rs933994), CYP2R1 (rs10741657) and DHCR7 (rs12785878) polymorphisms, (ii) to analyze the levels of DHCR7 and its associations with the lipid profile and (iii) to prospectively evaluate the effect of RA activity on the former associations in a group of patients followed-up upon Tumor Necrosis Factor alpha (TNFα)-blockade. The gene discussed is TNF; the disease is rheumatoid arthritis.