Hyperhomocysteinemia

Hyperhomocysteinemia
Classification and external resources
Homocysteine
ICD-9	270.4
DiseasesDB	29853
eMedicine	neuro/578

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.^{[citation needed]}

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.^{[citation needed]}

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.

See also

• Homocystinuria

Hyperhomocysteinemia is a risk factor for coronary artery disease and in cases of young myocardial infarction the level is found to be elevated.

• Methylenetetrahydrofolate reductase

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.