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Start free with EleplanHomocystinuria due to cystathionine beta-synthase deficiency
ORPHA:394Disease
Also called CBS-deficient HCU · Classical homocystinuria · Cystathionine beta-synthase deficiency · Cystathionine beta-synthase-deficient homocystinuria · Homocystinuria due to CBS deficiency
What it is
A rare metabolic disease of methionine catabolism characterized by accumulation of methionine and homocysteine with clinical involvement of the eye, skeletal system, vascular system and central nervous system (CNS).
Key facts
- Prevalence
- 1-9 / 100 000 (Europe)
- Age of onset
- Adolescent, Adult, Childhood
- Inheritance
- Autosomal recessive
- Classified as
- Disease
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Very common80–99%
9Common30–79%
17These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Gene
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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