What is hyperhomocystinuria?

Hyperhomocystinuria is a rare genetic disorder characterized by an elevated level of homocysteine, an amino acid, in the blood and urine. Homocysteine is a non-protein amino acid that is formed during the metabolism of methionine, an essential amino acid obtained from the diet. In hyperhomocystinuria, a genetic defect disrupts the body's ability to process homocysteine properly, leading to its accumulation.

There are various forms of hyperhomocystinuria, each caused by mutations in different genes involved in the metabolism of homocysteine. The most common form, classical homocystinuria, is inherited in an autosomal recessive manner, meaning both copies of the affected gene, one from each parent, must be altered to cause the disorder.

Elevated levels of homocysteine can have various adverse effects on the body. It can damage the blood vessel walls, leading to an increased risk of blood clots, stroke, and heart disease. Homocysteine can also affect connective tissue, bones, and the nervous system, causing a range of symptoms and complications.

Common manifestations of hyperhomocystinuria include:

1. Skeletal abnormalities: Individuals with hyperhomocystinuria may have long and slender limbs, a high-arched palate, and pectus excavatum (a sunken chest).

2. Ocular abnormalities: Ectopia lentis, a condition where the lens of the eye dislocates from its normal position, is commonly observed in hyperhomocystinuria.

3. Neurological problems: Homocysteine can damage the nervous system, leading to intellectual disability, seizures, speech difficulties, and psychiatric symptoms.

4. Cardiovascular issues: Increased homocysteine levels are associated with an elevated risk of developing blood clots, deep vein thrombosis, stroke, and coronary artery disease.

5. Pregnancy complications: Women with hyperhomocystinuria may face an increased risk of recurrent pregnancy loss, miscarriage, and neural tube defects in their children.

Early diagnosis and treatment of hyperhomocystinuria are crucial to reduce the risk of complications. Treatment typically involves dietary modifications to restrict methionine intake, as well as supplementation with vitamins, such as folate, vitamin B6, and vitamin B12, to help regulate homocysteine levels. In severe cases, medications may be prescribed to lower homocysteine. Regular monitoring and management by a healthcare team are essential to prevent or minimize the potential consequences of hyperhomocystinuria.