Hyperhomocysteinaemia is a medical condition characterized by an abnormally large level of homocysteine in the blood. As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of the vitamins pyridoxine (B6), folic acid (B9), or B12 can lead to high homocysteine levels. Supplementation with pyridoxine, folic acid, B12, or trimethylglycine (betaine) reduces the concentration of homocysteine in the bloodstream. Hyperhomocysteinaemia is a disease which increases risk of other artery or vein diseases. Hyperhomocysteinaemia usually occurs in people with at least one defective gene, which affects the breakdown of homocysteine...