RecruitingPhase 1 / Phase 2NCT03406611
Metabolic
Homocystinuria
Also known as CBS deficiency, cystathionine beta-synthase deficiency, classic 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 d
ORPHA:394 ↗Gene CBSPrevalence 1-9 per 100,000 (Orphanet)Onset Childhood, AdolescentAutosomal recessive genetic
5
studies recruiting now
as of 7 Sept 2026
22
studies registered in total
as of 7 Sept 2026
15
countries with a recruiting site
as of 7 Sept 2026
16 Aug 2024
most recent study posted
among recruiting studies
Recruiting trials
RecruitingPhase 3NCT06247085
A Study to Investigate Efficacy and Safety of Pegtibatinase Compared With Placebo in Participants ≥12 to ≤65 Years of Age With Classical Homocystinuria (HCU) Due to Cystathionine Beta Synthase Deficiency Receiving Standard of Care Treatment
RecruitingNCT06556615
Health Related Quality of Life (HrQoL) in Classical Homocystinuria (CBS Deficiency)
RecruitingNCT02998710
Natural History Study of Homocystinuria Caused by Cystathionine Beta-Synthase Deficiency (ACAPPELLA)
RecruitingNCT04880356
Longitudinal Study of Ultra-rare Inherited Metabolic and Degenerative Neurological Diseases.
Showing the 5 most recently updated recruiting studies, as recorded 7 Sept 2026. Live status on each study page.
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Countries with at least one recruiting site among the studies above, 7 Sept 2026. Tap a country to search trials there.
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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 lentisTall stature and Marfanoid habitusOsteoporosisThromboembolic eventsIntellectual disabilitySeizuresPsychiatric symptoms
From Orphanet’s phenotype annotations (CC BY 4.0). Not a complete list.
Before you apply
Things trial teams commonly ask about for Homocystinuria. Not eligibility rules; those are set by each study.
- 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
Related conditions
Information, not medical advice. Trial listings are shown as recorded on ClinicalTrials.gov; whether any study is right for you is a decision for you and your clinicians, and eligibility is decided by each research team. Disease information from Orphanet (CC BY 4.0).