Homocysteine levels in neurological disorders

Homocysteine (Hcy) is a sulphur-containing amino acid synthesized in one-carbon metabolic cycle. It is metabolized either by transsulfuration to cysteine or by remethylation to methionine. Plasma Hcy levels are often measured by collecting blood samples using the Hcy enzyme immunoassay (EIA) method. Several factors are known to increase hcy level including male gender, older age, higher body weight, lower folic acid and vitamin B dietary intake, cigarette smoking, alcohol abuse, chronic renal disease, as well as certain medications such as diuretics and fibrates. Interindividual differences in Hcy levels might be also attributed to certain genetic risk factors that influence the activity of one-carbon metabolism. Two single nucleotide polymorphisms in the methylenetetrahydrofolate reductase gene (MTHFR) -C677T and AI298C"”are among the most important genetic predictors of Hcy level and have been widely studied in numerous diseases that might be linked to alterations in one-carbon metabolism. Primarily, high Hcy levels have been exclusively regarded as a risk factor for cardiovascular diseases. Indeed, it has been found that Hcy may lead to endothelial injury triggering a cascade of processes resulting in atherosclerosis.