Mutations in MTRR and MTHFR genes cause changes in the gene expression and function of the MTRR enzyme and affect the level of homocysteine in the plasma leading to vascular endothelial damage and dysfunction leading to thrombophilia [23,24], which is an important factor in increasing the risk of preeclampsia [5,25,26]. The gene discussed is MTRR; the disease is preeclampsia.