Badiga, S., Johanning, G. L., Macaluso, M., Azuero, A., Chambers, M. M., Siddiqui, N. R., & Piyathilake, C. J. (2014). A lower degree of PBMC L1 methylation in women with lower folate status may explain the MTHFR C677T polymorphism associated higher risk of CIN in the US post folic acid fortification era. PLOS One, 9(10), e110093. doi: 10.1371/journal.pone.0110093
Studies in populations unexposed to folic acid (FA) fortification have demonstrated that MTHFR C677T polymorphism is associated with increased risk of higher grades of cervical intraepithelial neoplasia (CIN 2+). However, it is unknown whether exposure to higher folate as a result of the FA fortification program has altered the association between MTHFR C677T and risk of CIN, or the mechanisms involved with such alterations. The current study investigated the following in a FA fortified population: 1) The association between MTHFR C677T polymorphism and risk of CIN 2+; 2) The modifying effects of plasma folate concentrations on this association; and 3) The modifying effects of plasma folate on the association between the polymorphism and degree of methylation of long interspersed nucleotide elements (L1s), in peripheral blood mononuclear cell (PBMC) DNA, a documented biomarker of CIN risk.