Homocysteine and coronary heart disease. Is slight or moderate homocysteinemia related to increased risk of coronary heart disease?

Homocystinuria, a rare inherited disturbance of amino acid metabolism is associated with severe atherosclerosis and thromboembolism already in childhood. The incidence of the homozygous disease of cystathionine beta synthase is estimated to be 1:200,000, that of the heterozygous form 1:300. There are, however, numerous other causes of a mild to moderate homocysteinemia, for example, a deficiency of the cofactors vitamin B6, B12 and folic acid. The question as to whether a mild to moderate elevation of homocysteine in the plasma is also associated with an increased risk of CAD has been investigated in a number of studies in recent years. In summary, however, the presently available data do not provide a basis of proof that a mild to moderate homocysteinemia is an independent risk factor for CAD. Our present knowledge suggests that only when the family history is clearly positive does it appear reasonable to undertake a diagnostic search for possible homocysteinemia.