The 5-10 MTHFR enzyme therefore plays a central role in the metabolism of homocysteine (Hcy) and of folic acid, which is even more evident, as mutations and polymorphisms of the MTHFR gene lead to hyperhomocysteinemia and reduced levels of 5-MethylTHF [4,5]. This evidence concerns the gene MTHFR and hyperhomocysteinemia.