Homocysteine and Cerebral and Peripheral Vascular Disease

Severe hyperhomocysteinemia due to inherited deficiency of cystathionine β-synthase, 5,10-methylenetetrahydrofolate reductase (MTHFR), or certain enzymes in cobalamin metabolism results in life-threatening arteriosclerosis and venous and arterial thromboembolism in the very young [1–2]. In untreated hyperhomocysteinemia due to cystathione β-synthase deficiency, more than 50% of the cases will develop at least one thromboembolic event before the age of 30 [3]. Of interest is that only about 5% of the vascular events in cystathionine β-synthase deficiency affect the coronary arteries. In contrast, about 30% of the events are cerebrovascular, about 10% affect peripheral arteries, and more than 50% of the events are venous [4].