MTHFR and rheumatoid arthritis: A study published in 2012 by Brambila-Tapia et al. investigated methylenetetrahydrofolate reductase (MTHFR) polymorphisms A1298C, C677T, and A163G in osteoprotegerin in RA; the scientists measured the BMD in 71 Mexican patients with RA at the lumbar spine and femoral neck and used the restriction fragment length polymorphism to analyze the genotyping for the three MTHFR polymorphisms (CC, CT, and TT).