Evaluation of the Current Evidence on Hyperhomocysteinemia in Neurological Diseases

Abstract

Homocysteine (Hcy) is the demethylated product of methionine. This toxic amino acid can be removed by remethylation to methionine via methionine synthase, which utilizes 5-methyl tetrahydrofolate as a methyl donor and methyl cobalamin as a co-factor. An alternative remethylation pathway for Hcy depends on betaine-Hcy-methyltransferase, which utilizes betaine as a methyl donor. Another method of Hcy catabolism is via two vitamin-B 6 -dependent enzymes, cystathionine beta synthase and cystathioninase, to cysteine. subjects 70-79 years of age were followed for a mean of seven years. The