Homocysteine

Homocysteine is a non-proteinogenic <a href="/facts/%25CE%2591-amino_acid/WDxYwBny">α-amino acid</a>. It is a <a href="/facts/Homologous_series/7PKCuvzm">homologue</a> of the amino acid <a href="/facts/Cysteine/kbqvUm6d">cysteine</a>, differing by an additional <a href="/facts/Methylene_bridge/t3lvUJuT">methylene bridge</a> (−CH2−). It is biosynthesized from <a href="/facts/Methionine/7neydPKo">methionine</a> by the removal of its terminal Cε <a href="/facts/Methyl_group/fkM97EMD">methyl group</a>. In the body, homocysteine can be recycled into methionine or converted into cysteine with the aid of <a href="/facts/Vitamin_B6/9IavWjwM">vitamin B6</a>, <a href="/facts/Folate/8Eb7An6D">B9</a>, and <a href="/facts/Vitamin_B12/vCk613gD">B12</a>.
High levels of homocysteine in the blood (<a href="/facts/Hyperhomocysteinemia/PIosnq0g">hyperhomocysteinemia</a>) is regarded as a marker of cardiovascular disease, likely working through <a href="/facts/Atherogenesis/WIS8QQ6v">atherogenesis</a>, which can result in <a href="/facts/Ischemia/ySL9xbCl">ischemic injury</a>. Therefore, hyperhomocysteinemia is a possible risk factor for <a href="/facts/Coronary_artery_disease/szCt0nVx">coronary artery disease</a>. Coronary artery disease occurs when an atherosclerotic plaque blocks blood flow to the <a href="/facts/Coronary_artery/Xsx1dekd">coronary arteries</a>, which supply the heart with oxygenated blood.
Hyperhomocysteinemia has been correlated with the occurrence of blood clots, heart attacks, and strokes, although it is unclear whether hyperhomocysteinemia is an independent risk factor for these conditions. Hyperhomocysteinemia has also been associated with early-term spontaneous abortions and with <a href="/facts/Neural_tube_defects/3bK6SC0W">neural tube defects</a>.

Homocysteine open-in-new

Homocysteine