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ORPHA:394

Homocystinuria due to cystathionine beta-synthase deficiency

high confidenceDisorder

Also known as: CBS-deficient HCU · Classical homocystinuria · Cystathionine beta-synthase deficiency · Cystathionine beta-synthase-deficient homocystinuria · Homocystinuria due to CBS deficiency

Publications

844

82.7th percentile

Trials

5

Interventional, condition-specific

Researchers

1,213

Distinct authors in sample

Gene link

CBS

Definitive

Readiness

4/6

Stages with a signal

Clinical definition (Orphanet)

A rare 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).

How rare: 1-9 / 1 000 000 — roughly one to nine people per million. In a city the size of Kolkata, perhaps a few dozen.

Orphanet entry

Cross-references

Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.

Additional Mondo synonyms (6)

Homocystinuria due to Cystathionine Beta-Synthase Deficiency · classic homocystinuria · cystathionine beta-synthase deficiency · homocystinuria due to cystathionine beta-synthase deficiency · homocystinuria, B6-responsive and nonresponsive types · thrombosis, hyperhomocysteinemic

Research stages

Trial readiness signals

Where this condition sits on an open-data research pipeline — not how close a treatment is, and not medical advice. Empty stages often mean “not in these databases under this Mondo ID,” not “impossible.”

4/6 stages with a signal

An interventional trial matched this condition name on ClinicalTrials.gov — see trials below.

  1. Gene identifiedPresent

    Definitive — CBS

  2. LiteraturePresent

    844 matched papers (470 in last 10 years) Source

  3. Phenotype characterisedPresent

    109 HPO annotations (e.g. Dental crowding; Osteoporosis; Ectopia lentis) Source

  4. Animal modelNot found

    No Alliance genotype “model of” associations via Monarch for these Mondo IDs

  5. Orphan designationNot found

    No FDA or EMA orphan-drug designation matched this disease via UMLS or preferred name Source

  6. Interventional trialPresent

    5 matched on ClinicalTrials.gov (3 recruiting in sample)

Biology

Genes and phenotypes

Gene–disease validity from GenCC, plus phenotypes and animal models joined from Monarch Initiative via Mondo ID — not a clinical diagnosis aid.

Do we know what causes it?

Yes — we know a specific gene responsible (CBS).

GenCC classification: Definitive.

Phenotypes (Monarch / HPO)

109

Associated phenotypes · MONDO:0009352

  • Dental crowding
  • Osteoporosis
  • Ectopia lentis
  • Arachnodactyly
  • Intellectual disability

Showing 5 of 109 — open Monarch for the full list.

Animal models (Monarch / Alliance)

None returned for this Mondo ID. Empty here is not proof that no model organism work exists under another name or gene.

Monarch fetch 2026-07-29

Therapies

Designations, candidates, and chemicals

FDA OOPD and EMA orphan designations, Open Targets clinical candidates, and CTD chemical associations via MyDisease.info. These never change the interventional-trial headline.

Orphan designation (FDA · EMA)

No designation matched this disease via UMLS or preferred name on the FDA OOPD mirror or EMA orphan register. Absence here is not proof that none exists under another wording.

Open Targets candidates

2

Drugs / clinical candidates · MONDO_0009352

CTD chemicals (MyDisease.info)

No CTD chemical associations returned for this Mondo ID.

Literature

Is anyone studying this?

844

844 papers have been published on this condition. That is a real research literature — still far smaller than common diseases (breast cancer: over 700,000 papers). Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=3967) is 59.

844 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 59 (publications denominator n=3967).

470 in the last 10 years · high confidence · 82.7th percentile (publications denominator)

Phrase hits: 731 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

1,213

Distinct author names in 200 sampled papers — named people below.

Who's working on it?

People publishing on this condition (sampled Europe PMC records). Affiliation is the most recent found in that sample.

  1. 01
    Majtan T11 papers · 2026

    Section of Genetics and Metabolism, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.

    Papers in Europe PMC
  2. 02
    Kožich V6 papers · 2025

    Department of Pediatrics and Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital in Prague, Prague, Czechia.

    Papers in Europe PMC
  3. 03
    Kruger WD6 papers · 2024

    Cancer Signaling and Microenvironment Program, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA.

    Papers in Europe PMC
  4. 04
    Stabler SP6 papers · 2024

    Department of Medicine, University of Colorado School of Medicine, Aurora, CO 80045, USA.

    Papers in Europe PMC
  5. 05
    Karaca M5 papers · 2026

    Aksaray University, Faculty of Science and Arts, Department of Biology, Aksaray, Turkey.

    Papers in Europe PMC
  6. 06
    Levy HL5 papers · 2026

    Division of Genetics, Children's Hospital's, Boston, MA 02115, USA. harvey.levy@tch.harvard.edu

    Papers in Europe PMC
  7. 07
    Schwartz IVD5 papers · 2024

    Graduate Program in Medical Sciences, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.

    Papers in Europe PMC
  8. 08
    Wang J5 papers · 2026

    SUNY College of Optometry, New York, NY, USA.

    Papers in Europe PMC
  9. 09
    Yap S5 papers · 2003

    National Centre for Inherited Metabolic Disorders, Children's Hospital, Dublin, Ireland.

    Papers in Europe PMC
  10. 10
    Allen RH4 papers · 2017

    Department of Medicine, University of Colorado School of Medicine, Aurora, CO 80045, USA.

    Papers in Europe PMC

Clinical research

Is a treatment being tested?

5

interventional trials for this specific condition

5 interventional trials matched this specific condition name; 3 currently recruiting in our sample. 8 trials are registered for homocystinuria, the broader category — shown separately because they may or may not enrol this specific subtype.

Data as of 11 September 2026 · last trial check 28 July 2026

5 interventional trials — more than 77.2% of diseases in the trials denominator have none at all (5501 of 7126; this disease is at the 89.2th percentile).

high confidence · 89.2th percentile (trials denominator)

Recruiting interventional trials

From the matched ClinicalTrials.gov set

5 interventional trials matched after quoted-phrase search and title/condition post-filter.

Broader category: homocystinuria

8

Interventional trials for the parent category, exclusive of NCT IDs already counted above. Eligibility for this subtype is not guaranteed.

Worth raising with a clinician. How we count trials.

Observational and natural-history studies

3 observational studies match this condition. These do not test a treatment and are not counted in the interventional-trial headline, but they are genuine research: natural-history work often defines the endpoints needed for a future rare-disease trial, and families may be able to enroll.

Recruiting or not-yet-recruiting

Open the complete matched search on ClinicalTrials.gov

Other registries (secondary)

Broader net from EU CTIS, ISRCTN, and ICTRP when available — deduped against ClinicalTrials.gov IDs already counted above. Dual-model LLM relevance gates what we keep. These rows are not added to the interventional headline.

raw 2 · after dedupe 2 · already on CT.gov 0 · kept 0 · parent 0 · uncertain 2 · dropped 0 · fetched 2026-07-29

Source notes: ictrp: Error: ICTRP public search unavailable (WHO portal is SPA-only; SOAP needs partnership). Tried: https://apps.who.int/tri

No secondary-registry studies passed dual-model relevance for this condition name (after dedupe).

Uncertain / not reviewed (2)

Where to find support

Condition-specific patient organisations, when Orphanet lists them, are on the disease’s Orphanet page. We also link umbrella groups that support undiagnosed and ultra-rare families.

Orphanet entry for Homocystinuria due to cystathionine beta-synthase deficiency — check Associations / patient organisations on that page.

India — NPRD

Last verified 2026-07-26

Directly listed under NPRD Group 2.

Group 2 — long-term / lifelong lower-cost interventions

NPRD envisages State Government support for dietary formulae, hormones, and other lower-cost interventions. This is a different route from the central CoE ₹50 lakh pathway; ask your state health department and a CoE which channel applies.

Central CoE funding may also apply depending on current rules — confirm with a notified Centre of Excellence. Do not assume the ₹50 lakh ceiling covers Group 2 by default. Verify

Centres of Excellence (15)
  • All India Institute of Medical Sciences (AIIMS) — New Delhi, Delhi
  • Maulana Azad Medical College — New Delhi, Delhi
  • Sanjay Gandhi Post Graduate Institute of Medical Sciences — Lucknow, Uttar Pradesh
  • Post Graduate Institute of Medical Education and Research (PGIMER) — Chandigarh, Chandigarh
  • Centre for DNA Fingerprinting & Diagnostics with Nizam’s Institute of Medical Sciences — Hyderabad, Telangana
  • King Edward Memorial Hospital — Mumbai, Maharashtra
  • Institute of Post-Graduate Medical Education and Research (IPGMER) — Kolkata, West Bengal
  • Centre for Human Genetics with Indira Gandhi Hospital — Bengaluru, Karnataka
  • Institute of Child Health and Hospital for Children (ICH & HC) — Chennai, Tamil Nadu
  • All India Institute of Medical Sciences (AIIMS) — Jodhpur, Rajasthan
  • Sree Avittam Thirunal Hospital (SAT), Government Medical College — Thiruvananthapuram, Kerala
  • All India Institute of Medical Sciences (AIIMS) — Bhopal, Madhya Pradesh
  • Regional Institute of Medical Sciences (RIMS) — Imphal, Manipur
  • All India Institute of Medical Sciences (AIIMS) — Patna, Bihar
  • Assam Medical College & Hospital — Dibrugarh, Assam

Voluntary contributions / crowdfunding (separate from CoE funding): https://rarediseases.mohfw.gov.in/

Hand-curated for this project. ORPHAcode mappings are best-effort and may be incomplete or imprecise for umbrella categories. Parent (Mondo) matches mean the policy lists a broader category — confirm eligibility with a Centre of Excellence. Financial entitlements summarised from public policy statements and may change. This is not official government guidance.

How we counted this

Europe PMC query (preferred label + any corrected label + Orphanet and Mondo exact synonyms, stoplisted; unioned with resolved MeSH labels when available). UMLS / OMIM / NCIT cross-references are stored on the overview but are not added to the query string.

("Homocystinuria due to cystathionine beta-synthase deficiency" OR "CBS-deficient HCU" OR "Classical homocystinuria" OR "Cystathionine beta-synthase deficiency" OR "Cystathionine beta-synthase-deficient homocystinuria" OR "Homocystinuria due to CBS deficiency" OR "classic homocystinuria" OR "homocystinuria, B6-responsive and nonresponsive types" OR "thrombosis, hyperhomocysteinemic") OR ("CBS syndrome" OR "CBS-related")

Run this search on Europe PMC

ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):

"Homocystinuria due to cystathionine beta-synthase deficiency" OR "CBS-deficient HCU" OR "Classical homocystinuria" OR "Cystathionine beta-synthase deficiency" OR "Cystathionine beta-synthase-deficient homocystinuria" OR "Homocystinuria due to CBS deficiency" OR "classic homocystinuria" OR "homocystinuria, B6-responsive and nonresponsive types" OR "thrombosis, hyperhomocysteinemic"

Interventional trials matched via: phrase (mesh = registered under a MeSH descriptor no name phrase would catch; recall-expansion = gene / selected parent terms used only for trials).

Study-type breakdown: 5 interventional · 3 observational · 0 expanded access. Only interventional studies enter the trial headline.

Parent-category trials query:

"homocystinuria"

Query health: ok — strategies attempted: phrase; with hits: phrase

Run this search on ClinicalTrials.gov

Confidence reasoning

  • Preferred label is multi-word and distinctive
  • No synonyms dropped by stoplist
  • No label/synonym collisions with other diseases in this corpus

Ingested 2026-07-26T13:41:55.461Z