Molecular genetics of homocysteine metabolism.

Recent genetic studies have led to the characterization of molecular determinants contributing to the pathogenesis of hyperhomocysteinemia. In this article we summarize the current insights into the molecular genetics of severe, moderate and mild hyperhomocysteinemia. We will consider deficiencies of the trans-sulfuration enzyme cystathionine beta-synthase (gene symbol: CBS), and the disturbances of the remethylation enzymes 5, 10-methylenetetrahydrofolate reductase (gene symbol: MTHFR), methionine synthase (gene symbol: MTR), and the recently identified methionine synthase reductase (gene symbol: MTRR). Furthermore, we will focus on clinically important genetic polymorphisms which are highly prevalent and thus of potential general interest.