MTHFR and rheumatoid arthritis: Considering all the above, many studies aim to prove whether there is a potential contribution of the MTHFR 677 C>T and 1298 A>C gene polymorphisms to disease susceptibility of patients with RA or if it may be correlated with an increased risk of subclinical atherosclerosis manifested by the presence of endothelial dysfunction in RA [41,42].