Homocysteine: a reversible risk factor for coronary heart disease

Homocysteine is a sulphur-containing amino acid, derived from the metabolism of methionine. Homocysteine concentrations are determined by genetic and nutritional factors; mutations in the genes for enzymes involved in homocysteine metabolism, such as the common 5,10-methylenetetrahydrofolate reductase (MTHFR) 677→T mutation, and deficiencies of vitamins B6, B12 and folic acid are associated with hyperhomocysteinaemia.