Hyperhomocysteinemia (HHcy) defined as the concentration of plasma total homocysteine (tHcy) of ≥10 μmol/L7, is often a consequence of reduced enzymatic activity involved in homocysteine metabolism, such as a point mutation of methylenetetrahydrofolate reductase (MTHFR) in which cytosine is replaced by thymidine at position 677 (MTHFR C677T)8. This evidence concerns the gene MTHFR and hyperhomocysteinemia.