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 (hō′mə-sĭs′tə-ēn′, -ĭn, -tē-)
An amino acid, C4H9NO2S, not found in proteins, that is used by the body in cellular metabolism. Elevated concentrations in the blood are associated with an increased risk of heart disease.

[homo-, homologous with (from homologous) + cysteine.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Chemistry) an amino acid occurring as an intermediate in the metabolism of methionine. Elevated levels in the blood may indicate increased risk of cardiovascular disease
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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Significant correlation was found between systolic blood pressure (r: 0.239, p: 0.007) and duration of diabetes with homocysteine (r: 0.302, p: 0.001).
If homocysteine accumulates in the bloodstream, however, a host of problems follow.
Participants in both groups were evaluated for plasma homocysteine levels, by collection into a heparinized tube and later transferred in ice blocks.
An article published in 2017 reported on the growing epidemiological evidence of a strong association between elevated homocysteine and hearing loss.
Meta-analysis of cross-sectional studies have suggested that increased serum Homocysteine concentration is associated with 60 percent increase in the incidence of cardiovascular diseases.
Despite the accumulating evidence describing the effect of homocysteine on CV function, few studies with conflicting results have examined CV effects of homocysteine in rheumatoid arthritis.
Increasing plasma homocysteine level is associated with elevating the risk of systemic vascular disease through enhancement of the adverse effects of risk factors such as hypertension, smoking, and lipid and lipoprotein metabolism, as well as acceleration of development of inflammation.
DNA methylation has long been recognized as an epigenetic silencing mechanism and plays important roles in many cellular processes, such as gene transcription, genomic imprinting, and X-chromosome inactivation.[sup][3] Homocysteine is an amino acid produced in the liver after the metabolism of methionine.
"This is the first observational investigation stratified by sex to evaluate the correlation between sexual frequency and serum homocysteine levels," wrote the researchers, in the (http://www.jsm.jsexmed.org/article/S1743-6095(17)31193-1/fulltext) study  published in the Journal of Sexual Medicine.
Homocystinuria is the term used for several rare genetic disorders (diseases passed down through families) that cause levels of homocysteine to build up in blood and urine.
Homocysteine is a non-protein-forming sulfur-containing amino acid first described by Butz and du Vigneaud in 1932.