Homocystinuria (HCY)


Homocystinuria (HCY) is a condition in which the body is unable to break down certain proteins. HCY is considered an amino acid condition because individuals with HCY cannot process certain amino acids or small molecules that make up proteins. These amino acids build up in the body and can cause serious health problems. There are multiple forms of HCY. They are distinguished by their signs, symptoms, and genetic cause.

This condition may cause various health concerns such as eye problems, developmental delay, or learning problems. However, if HCY is detected early and treatment is begun, children with HCY can often lead healthy lives. This condition is also known as: homocystinemia, cystathionine beta-synthase deficiency, CBS deficiency.

To learn more about Homocystinuria, visit Screening, Technology, and Research in Genetics (STAR-G): Homocystinuria and Baby's First Test: Homocystinuria. Please see Medically Prescribed Formula for information about medically prescribed formula and pharmacologic interventions for inborn errors of metabolism. Visit Board Certified Metabolic Providers (PDF: 2 pages/204KB) for a listing of medical specialists and clinic contact information.