ORPHA:622
Homocystinuria without methylmalonic aciduria
Also known as: Functional methionine synthase deficiency · Methylcobalamin deficiency
Publications
61
43.1th percentile
Trials
0
Interventional, condition-specific
Researchers
354
Distinct authors in sample
Gene link
—
Readiness
2/6
Stages with a signal
Clinical definition (Orphanet)
Homocystinuria without methylmalonic aciduria is an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, and, sometimes, , and associated with homocystinuria and hyperhomocysteinemia. There are three types of homocystinuria without methylmalonic aciduria; cblE, cblG and cblD-variant 1 (cblDv1).
How rare: <1 / 1 000 000 — fewer than one in a million. In a city the size of Kolkata, that might mean on the order of fifteen people.
Cross-references
Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.
- MONDO:0018964
- UMLS:C4303479
Additional Mondo synonyms (3)
functional methionine synthase deficiency · homocystinuria without methylmalonic aciduria · methylcobalamin deficiency
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.”
2/6 stages with a signal
No specific-condition interventional trial, but broader-category trials exist — discuss eligibility with a clinician.
- Gene identifiedNot found
No GenCC disease–gene assertion in this build
- LiteraturePresent
61 matched papers (29 in last 10 years) Source
- Phenotype characterisedNot checked
Not yet enriched from Monarch / HPO
- Animal modelNot checked
Not yet enriched from Monarch / Alliance
- Orphan designationNot checked
FDA/EMA orphan-drug designation not enriched yet
- Interventional trialPartial
None under the specific name; 13 for broader category homocystinuria
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?
Not yet — the cause hasn't been pinned down in GenCC.
No strong gene–disease assertion joined for this Orphanet entity.
Phenotypes (Monarch / HPO)
Not enriched in this build — Monarch phenotype joins were not run for this record.
Animal models (Monarch / Alliance)
Not enriched in this build.
Literature
Is anyone studying this?
61
61 papers have ever been published on this condition (under this name). For scale, breast cancer has over 700,000. Median papers in the last 10 years for a rare disease in this dataset (publications denominator n=5449) is 41.
61 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 41 (publications denominator n=5449).
29 in the last 10 years · high confidence · 43.1th percentile (publications denominator)
Phrase hits: 61 · MeSH hits: 0
Who's working on it?
354
Distinct author names in 61 sampled papers — named people below.
Who's working on it?
No interventional trial matched this name; these authors publish on it in the sampled literature — a practical starting point for contact.
- 01Rosenblatt DS10 papers · 2012Papers in Europe PMC
- 02Watkins D5 papers · 2012
Division of Medical Genetics, Department of Medicine, McGill University Health Centre, Montreal, Quebec, H3A 1A1, Canada. dwatkins@generation.net
Papers in Europe PMC - 03
- 04Banerjee R2 papers · 1997Papers in Europe PMC
- 05Brody LC2 papers · 1997Papers in Europe PMC
- 06Chen Z2 papers · 2020
Department of Pediatrics, Peking University First Hospital, Beijing, 100034, China.
Papers in Europe PMC - 07Cooper BA2 papers · 1987Papers in Europe PMC
- 08Gravel RA2 papers · 2007Papers in Europe PMC
- 09Gulati S2 papers · 1997
Biochemistry Department, University of Nebraska, Lincoln 68588-0664, USA.
Papers in Europe PMC - 10Gupta A2 papers · 2024
Department of Paediatric Surgery, Lokmanya Tilak Municipal General Hospital, Mumbai, Maharashtra, India.
Papers in Europe PMC
Clinical research
Is a treatment being tested?
0
interventional trials for this specific condition
No interventional trial testing a treatment matched this specific condition name. 1 observational study did — shown below because natural-history and cohort work can be an important step toward a trial. 13 trials are registered for homocystinuria, the broader category — shown separately because they may or may not enrol this specific subtype.
Data as of 27 July 2026
No matched interventional trials. This is true for 73% of diseases in the trials denominator (5114 of 7003). Here are the researchers publishing on it.
high confidence · 36.5th percentile (trials denominator)
Recruiting interventional trials
From the matched ClinicalTrials.gov set
No interventional trial testing a treatment was found for this specific condition name on ClinicalTrials.gov.
13 interventional trials matched homocystinuria, the broader category — listed below. Those studies are not counted in the condition-specific total.
Broader category: homocystinuria
13
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.
Recruiting under the broader category
- NCT06247085·RECRUITING·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
Conditions: Homocystinuria·Matched via name phrase
- NCT06622577·NOT YET RECRUITING·The Effect of Dietary Management and Cysteine Supplementation on Growth Parameters and Biochemical Control for Pediatric Qatari Patients Affected with Classical B6 Non-responsive Homocystinuria.
Conditions: Classical Homocystinuria·Matched via name phrase
- NCT06431893·ENROLLING BY INVITATION·A Long-term Extension Study to Assess the Long-term Safety and Efficacy of Pegtibatinase Treatment in Participants ≥5 to ≤65 Years of Age With Classical Homocystinuria (HCU) (ENSEMBLE)
Conditions: Homocystinuria·Matched via name phrase
Observational and natural-history studies
1 observational study matches 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.
None of the matched observational studies is currently listed as recruiting.
Where to find support
We do not yet link condition-specific patient organisations. These umbrella groups support undiagnosed and ultra-rare families:
India — NPRD
Last verified 2026-07-26Likely covered — the policy lists Homocystinuria as a category (Group 2), and this condition is a form of it. Confirm eligibility with a Centre of Excellence.
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 without methylmalonic aciduria" OR "Functional methionine synthase deficiency" OR "Methylcobalamin deficiency"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Homocystinuria without methylmalonic aciduria" OR "Functional methionine synthase deficiency" OR "Methylcobalamin deficiency"
Study-type breakdown: 0 interventional · 1 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 2026-07-26T14:35:54.478Z