Disease Directory Homocystinuria
Metabolic

Homocystinuria

Also known as: CBS deficiency, cystathionine beta-synthase deficiency, classic homocystinuria

Prevalence

1-9 per 100,000 (Orphanet)

Onset

Childhood, Adolescent

Type

Autosomal recessive genetic

Gene

CBS

About Homocystinuria

Classic homocystinuria is caused by deficiency of cystathionine beta-synthase (CBS), which leads to accumulation of homocysteine in the blood and urine. Elevated homocysteine causes multisystem complications including ectopia lentis (lens dislocation), intellectual disability, skeletal abnormalities resembling Marfan syndrome, and a markedly elevated risk of thromboembolic events including stroke. Pyridoxine (vitamin B6) responsiveness defines a milder subtype with better dietary treatment outcomes.

Common Clinical Features

Ectopia lentis Tall stature and Marfanoid habitus Osteoporosis Thromboembolic events Intellectual disability Seizures Psychiatric symptoms

Clinical Trial Eligibility Tips

What to know before applying to Homocystinuria trials.

Pyridoxine (B6) responsiveness testing is a prerequisite — responders and non-responders are enrolled in different trial arms

Plasma total homocysteine level is the primary efficacy endpoint and eligibility biomarker

Thromboembolic history significantly affects eligibility — anticoagulation requirements must be disclosed

mRNA and gene therapy trials are emerging — no prior gene therapy is a typical exclusion criterion

Patient Resources

Patient Organization

HCU Network America

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Natural History Registry

HCU Registry

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Orphanet

European reference resource for rare diseases (ORPHA:394)

View on Orphanet ↗

NORD

National Organization for Rare Disorders

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Find recruiting Homocystinuria trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for Homocystinuria. Updated daily.

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