Diagnostics of Homocysteine Metabolism

Homocysteine (Hcy) was discovered in 1932 by Du Vigneaud [27] as a product of demethylation of methionine, and in 1962, Carson and Neill [19] reported on to two siblings with the inborn error homocystinuria detected by a screening program of mentally retarded children. Since then about 600 patients with homocystinuria have been reported [64]. Deficiency of the enzyme cystathionine s-synthase is the most common cause, but other enzymic defects have been described in a minority of these patients. Notably, all forms of homocystinuria, irrespective of enzymic defect, are associated with a high incidence of cardiovascular disease that may occur in early adolescence and even in childhood [64]. The high incidence of vascular disease in these patients led to the Hey theory of atherosclerosis, formulated by McCully in 1975 [62, 61] and later substantiated by epidemiological data [52, 88].