Hyperhomocysteinemia
Encyclopedia
Hyperhomocysteinemia or hyperhomocysteinaemia is a medical condition characterized by an abnormally large level of homocysteine
in the blood
.
As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of the vitamins pyridoxine
(B6), folic acid
(B9), or B12
can lead to high homocysteine levels.
Supplementation with pyridoxine, folic acid, B12, or trimethylglycine
(betaine) reduces the concentration of homocysteine in the bloodstream.
Hyperhomocysteinemia is a disease which increases risk of other artery or vein diseases.
Hyperhomocysteinemia usually occurs in people with at least one defective gene, which affects the breakdown of homocysteine. There are two common gene defects in the population. The first gene codes for an enzyme. This gene is known as methylenetetrahydrofolate reductase
or MTHFR. The second common defective gene is methioninesynthetase or MS.
Hyperhomocysteinemia is a high level of homocysteine in human blood. A high level of homocysteine makes a person more prone to endothelial injury, which leads to vascular inflammation, which in turn may lead to atherogenesis, which can result in ischemic injury. Hyperhomocysteinemia is therefore a risk factor for coronary artery disease. Coronary artery disease is when an atherosclerosis leads to occlusion of the lumina of the coronary arteries. These arteries supply the heart with oxygenated blood.
People who are most likely to get hyperhomocysteinemia are with two defective genes and having a diet low in folate and vitamin B6 and B12. The effect upon these people is greater than the people with only one defective gene.
Hyperhomocysteinemia is linked to an increased risk of blood clots, heart attacks and strokes. It can cause miscarriage, pre-eclampsia and other birth defects in pregnant women.
The best way to prevent hyperhomocysteinemia is to eat foods which contain B6, B12, and folate such as potato, greens, beans and fish. The only natural sources of B12 are from animal products.
However, it is difficult to show that reducing your homocysteine levels will improve your health. In a study designed to see if lowering homocysteine will reduce heart ("vascular
") and kidney problems, the results were just the opposite. Patients with diabetes and known kidney disease ("diabetic nephropathy
") were given commonly used doses of B vitamins: folic acid
(2.5 mg/d), vitamin B6
(25 mg/d), and vitamin B12
(1 mg/d). Diabetics usually have elevated homocysteine levels and a higher risk for heart attacks and strokes, so they make an ideal population to study homocysteine's effects on human health. Taking B vitamins did reduce homocysteine, as expected, but unfortunately doubled the patient's risk of serious vascular complications (heart attack, stroke, death) and worsened their kidney function.
Hyperhomocysteinemia is a risk factor for coronary artery disease and in cases of young myocardial infarction the level is found to be elevated.
MTHFR (A1298C) DNA Gene mutation has been associated with an increased risk for hyperhomocysteinemia. MTHFR is involved in the methylation of homocysteine to methionine. Individuals with MTHFR gene mutations that reduce enzyme activity, may develop hyperhomocysteinemia and thus be at risk for vascular disease.
Homocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
in the blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
.
As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of the vitamins pyridoxine
Vitamin B6
Vitamin B6 is a water-soluble vitamin and is part of the vitamin B complex group. Several forms of the vitamin are known, but pyridoxal phosphate is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation...
(B6), folic acid
Folic acid
Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...
(B9), or B12
Cyanocobalamin
Cyanocobalamin is an especially common vitamer of the vitamin B12 family. It is the most famous vitamer of the family, because it is, in chemical terms, the most air-stable...
can lead to high homocysteine levels.
Supplementation with pyridoxine, folic acid, B12, or trimethylglycine
Trimethylglycine
Trimethylglycine is an organic compound that occurs in plants as either glycine betaine or a choline-containing glycine betaine compound. Trimethylglycine was the first betaine discovered by science; originally it was simply called betaine because, in the 19th century, it was discovered in sugar...
(betaine) reduces the concentration of homocysteine in the bloodstream.
Hyperhomocysteinemia is a disease which increases risk of other artery or vein diseases.
Hyperhomocysteinemia usually occurs in people with at least one defective gene, which affects the breakdown of homocysteine. There are two common gene defects in the population. The first gene codes for an enzyme. This gene is known as methylenetetrahydrofolate reductase
Methylenetetrahydrofolate reductase
Methylenetetrahydrofolate reductase is an enzyme that in humans is encoded by the MTHFR gene. Methylenetetrahydrofolate reductase catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a cosubstrate for homocysteine remethylation to methionine...
or MTHFR. The second common defective gene is methioninesynthetase or MS.
Hyperhomocysteinemia is a high level of homocysteine in human blood. A high level of homocysteine makes a person more prone to endothelial injury, which leads to vascular inflammation, which in turn may lead to atherogenesis, which can result in ischemic injury. Hyperhomocysteinemia is therefore a risk factor for coronary artery disease. Coronary artery disease is when an atherosclerosis leads to occlusion of the lumina of the coronary arteries. These arteries supply the heart with oxygenated blood.
People who are most likely to get hyperhomocysteinemia are with two defective genes and having a diet low in folate and vitamin B6 and B12. The effect upon these people is greater than the people with only one defective gene.
Hyperhomocysteinemia is linked to an increased risk of blood clots, heart attacks and strokes. It can cause miscarriage, pre-eclampsia and other birth defects in pregnant women.
The best way to prevent hyperhomocysteinemia is to eat foods which contain B6, B12, and folate such as potato, greens, beans and fish. The only natural sources of B12 are from animal products.
However, it is difficult to show that reducing your homocysteine levels will improve your health. In a study designed to see if lowering homocysteine will reduce heart ("vascular
Vascular
Vascular in zoology and medicine means "related to blood vessels", which are part of the circulatory system. An organ or tissue that is vascularized is heavily endowed with blood vessels and thus richly supplied with blood....
") and kidney problems, the results were just the opposite. Patients with diabetes and known kidney disease ("diabetic nephropathy
Diabetic nephropathy
Diabetic nephropathy , also known as Kimmelstiel-Wilson syndrome, or nodular diabetic glomerulosclerosis and intercapillary glomerulonephritis, is a progressive kidney disease caused by angiopathy of capillaries in the kidney glomeruli. It is characterized by nephrotic syndrome and diffuse...
") were given commonly used doses of B vitamins: folic acid
Folic acid
Folic acid and folate , as well as pteroyl-L-glutamic acid, pteroyl-L-glutamate, and pteroylmonoglutamic acid are forms of the water-soluble vitamin B9...
(2.5 mg/d), vitamin B6
Vitamin B6
Vitamin B6 is a water-soluble vitamin and is part of the vitamin B complex group. Several forms of the vitamin are known, but pyridoxal phosphate is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation...
(25 mg/d), and vitamin B12
Vitamin B12
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins...
(1 mg/d). Diabetics usually have elevated homocysteine levels and a higher risk for heart attacks and strokes, so they make an ideal population to study homocysteine's effects on human health. Taking B vitamins did reduce homocysteine, as expected, but unfortunately doubled the patient's risk of serious vascular complications (heart attack, stroke, death) and worsened their kidney function.
See also
- HomocystinuriaHomocystinuriaHomocystinuria, also known as cystathionine beta synthase deficiency or CBS deficiency, is an inherited disorder of the metabolism of the amino acid methionine, often involving cystathionine beta synthase...
Hyperhomocysteinemia is a risk factor for coronary artery disease and in cases of young myocardial infarction the level is found to be elevated.
- Methylenetetrahydrofolate reductaseMethylenetetrahydrofolate reductaseMethylenetetrahydrofolate reductase is an enzyme that in humans is encoded by the MTHFR gene. Methylenetetrahydrofolate reductase catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, a cosubstrate for homocysteine remethylation to methionine...
MTHFR (A1298C) DNA Gene mutation has been associated with an increased risk for hyperhomocysteinemia. MTHFR is involved in the methylation of homocysteine to methionine. Individuals with MTHFR gene mutations that reduce enzyme activity, may develop hyperhomocysteinemia and thus be at risk for vascular disease.