Homocystine as a Risk Factor for Vascular Diseases

Homocystine is an amino acid, which is known for its congenitally acquired disease, Homocystinurea. Researchers have proposed that elevated plasma Homocystine may be associated with atherosclerosis. Patients with mild to moderate hyperhomocytinemia (seen in 5-7%of population) may be asymptomatic until third and forth decade that they may refer with coronary artery disease or recurrent arterial or venous thrombosis. Sever hyperhomocytinemia is relatively rare and is usually seen as homocystinurea. Normal plasma level of Homocystine is 5 - 15μmol/l (higher in men than premenopausal women). Causes of hyperhomocystinemia include: 1- enzymatic defects (Cystathione ß-synthase deficiency (the most common enzymatic defect), MTHFR deficiency, Methionine synthase deficiency), 2- dietary deficiency (folate, Vit B12, Vit B6) and 3- other causes (renal failure, liver disorders, hypothyroidism, malignancy including breast, ovarian or pancreatic cancers and drugs (such as methotrexate, trimetoprim, cholestyramine, colestipole, phenytion, carbamazepine, niacin, theophylin, cyclosporine and fibric acid derivatives). Treatment of hyperhomocysteinemia is vitamin supplementation and nutritional intervention.