Hyperhomocysteinemia Definition

It is a medical disorder that is marked by an unusual increase of homocysteine levels in the bloodstream. It is a rare disease that affects less than 200,000 individuals in the United States.

The disorder is known by many other names like:

  • Hereditary homocystinuria
  • Homocysteine elevation
  • Homocystinemia
  • Homocysteinemia
  • Hyperhomocystinemia

Hyperhomocysteinemia Types

Depending on total plasma homocysteine concentration in fasting individuals, medical researchers categorize this condition into three types. These are:

Severe Hyperhomocysteinemia

It is defined as a condition in which fasting concentration of total plasma homocysteine is higher than 100 µM.

Moderate Hyperhomocysteinemia

This subtype is characterized by fasting concentration of total plasma homocysteine lying in a range of 15-100 µM.

Normal Hyperhomocysteinemia

In this type, mean fasting concentrations of total plasma homocysteine are generally less than or equal to 10 µM. The 95th percentile is approximately found at less than 15 µM.

Hyperhomocysteinemia Symptoms

As previously mentioned, the condition is characterized by an increased homocysteine level in human blood. A high homocysteine level makes an individual more vulnerable to endothelial injury, which results in vascular inflammation. This, in turn, may give rise to atherogenesis and consequently, Ischemic injury.

Some of the main symptoms of Hyperhomocysteinemia, which include complicated disorders, are:

  • Vascular abnormalities
  • Deep venous thrombosis
  • Pulmonary embolism
  • Ischemic stroke
  • Transient ischemic attack
  • Cerebral venous thrombosis
  • Neurologic abnormalities
  • Myocardial infarction
  • Peripheral vascular disease
  • Corneal abnormalities
  • Skeletal abnormalities
  • Eye problems
  • Mental retardation
  • Psychiatric disorders
  • Seizures
  • Myopia
  • Retinal Detachment
  • Glaucoma
  • Cataracts
  • Pes cavus
  • Increased length of long bones
  • Arachnodactyly
  • Scoliosis
  • Osteoporosis

Some other abnormalities caused by this disease include fatty infiltration of liver, endocrine problems and Myopathy.

Hyperhomocysteinemia Causes

The condition is primarily caused by Folate deficiency. Some other causes of Hyperhomocysteinemia are:

  • Insufficient B12 intake
  • Defective renal function
  • Diet lacking in Vitamin B6, Vitamin B12 or Folate
  • Kidney disorders
  • Excessive exercise
  • Medicinal side effect

Hyperhomocysteinemia and Genetics

Hyperhomocysteinemia can appear due to the presence of one or two acquired mutated genes. These genes lead to a failure in degradation of Homocysteine, a chemical that naturally occurs in the human body.

The problem is often found to arise due to variations in genes, including the MTHFR gene. An individual with a single MTHFR genetic mutation suffers from moderate increase of Homocysteine. Those with double mutations, or a homozygous mutation, suffer from a more severe form of Hyperhomocysteinemia. The effect on people with two mutated genes is greater than individuals with only one.

Hyperhomocysteinemia Diagnosis

A diagnosis of hyperhomocysteinemia is carried out on the assumption that patients stand at an increased risk of becoming premature sufferers of vascular disorders like Atherosclerosis. The diagnosis is established on the basis of the lab measurement values of total plasma homocysteine. Homocysteine-regulated polynucleotide probes are also used to diagnose this disease.

In Total Plasma Homocysteine, laboratory assays usually determine the full concentration of free thiol, disulfide, and mixed disulfide forms of homocysteine. It is common and more convenient to perform this test while a patient is fasting. A “Post-methionine Loading” test is also conducted to measure total plasma homocysteine levels after “methionine loading” or protein meal. The test is conducted 2 hours after Methionine (0.1 g/kg) is orally administered. Post-methionine Loading test is believed to have higher sensitivity than a Fasting Total Plasma Homocysteine test.

In case of an elevated Homocysteine, testing levels of Vitamin B6, Vitamin B12 and Folate may aid in deciding whether supplementation of any of these specific vitamins can be effective.

Specified tests for detecting particular DNA mutations in 5,10-methylenetetrahydrofolate reductase or cystathionine beta-synthase are also available in reference laboratories.

Hyperhomocysteinemia Treatment

Most causes of Hyperhomocysteinemia can be corrected by Folate supplementation. Treatment for hyperhomocysteinemia also includes

  • Vitamin supplementation
  • Low-protein diet
  • Anticoagulants

These curative approaches do not always yield effective results. In some cases, however, they help prolong the lifespan of any individual diagnosed with highly elevated levels of Homocysteine. A change in diet can be quite effective in people who suffer from situational increase in Homocysteine levels.

Hyperhomocysteinemia Prognosis

The outcome of this condition varies in patients. This disorder has a high mortality rate. In individuals with severe Hyperhomocysteinemia, pulmonary embolism, myocardial infarction and stroke are found to be the chief causes of death. In patients with Coronary Artery Disease, moderate Hyperhomocysteinemia has been detected as a strong predictor of mortality.

Hyperhomocysteinemia Complications

This disorder is associated with several vascular, neurological, and skeletal problems including stroke, heart attack, clotting, mental retardation, eye abnormalities, and osteoporosis, amongst many other complications.

Hyperhomocysteinemia increases the risk of having Coronary Artery Disease. Coronary artery disease occurs when an atherosclerosis results in obstruction of the lumina of the coronary arteries, which supply oxygenated blood to the heart.

The disorder also makes patients susceptible to other complications like:

  • Clotting
  • Coronary thrombosis
  • Stroke
  • Heart attack
  • Venous thrombosis

Hyperhomocysteinemia and Pregnancy

In pregnant women, Hyperhomocysteinemia can lead to a number of complications. It can cause miscarriage, recurrent loss of pregnancy and birth of stillborn children. It may also be involved with birth defects like pre-eclampsia and in the pathogenesis of neural tube defects.

Hyperhomocysteinemia Prevention

This condition can best be prevented by consumption of foods such as green vegetables, fish, potato and beans that are rich in Vitamin B6, B12 and Folate. Animal products, which are known to be the only natural sources of Vitamin B12, should be used to keep this disease at bay. However, there is not enough substantial medical proof to show that reducing Homocysteine levels will actually improve health of Hyperhomocysteinemia sufferers. Intake of Folic acid supplements can be beneficial in lowering homocysteine levels in patients of mild genetic Hyperhomocysteinemia.

Call your healthcare provider immediately if you suspect yourself or any family member to be having this condition. Seeking timely medical attention to this problem can help you check it in the early stages and prevent development of further complications.






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