Homocystinuria (HCU) is a rare inherited condition where the body cannot properly process certain amino acids, the building blocks of protein. Normally, the body uses enzymes (with help from vitamin B6) to convert homocysteine into other useful substances. In the most common form, this process doesn’t work due to a deficiency of an enzyme called cystathionine beta-synthase (CBS).
As a result, homocysteine builds up in the blood and urine, gradually affecting multiple parts of the body, such as the eyes, bones, blood vessels, and the brain. Common signs include dislocated eye lenses, a tall and slender build, brittle bones, a risk of blood clots, and developmental delays. Symptoms often appear in early childhood, though mild cases may go unnoticed for years.
Having a family history of the condition or inheriting faulty genes from both parents is the primary risk factor for homocystinuria. While homocystinuria cannot be cured, it can be managed effectively. Treatment usually includes a special low-protein diet, vitamin B6 supplements, and, in some cases, specific medications. When caught early and managed well, most people can live a healthy, active life.
