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ORPHA:415

Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome

high confidenceDisorder

Also known as: HHH syndrome · ORNT1 deficiency · Ornithine carrier deficiency · Ornithine translocase deficiency · Triple H syndrome

Publications

913

85.3th percentile

Trials

0

Interventional, condition-specific

Researchers

1,369

Distinct authors in sample

Gene link

SLC25A15

Definitive

Readiness

4/6

Stages with a signal

Clinical definition (Orphanet)

A rare, genetic disorder of urea cycle metabolism characterized by either a -onset with manifestations of lethargy, poor feeding, vomiting and tachypnea or, more commonly, presentations in infancy, childhood or adulthood with chronic neurocognitive deficits, acute and/or coagulation defects or other chronic liver dysfunction.

How rare: How common this is has not been clearly measured.

Orphanet entry

Cross-references

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

Additional Mondo synonyms (4)

hyperornithinemia-hyperammonemia-homocitrullinemia syndrome · ornithine carrier deficiency · ornithine translocase deficiency · triple H syndrome

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

No matched interventional trial; the gene is known and literature exists — preclinical or natural-history work may still be the practical next step.

  1. Gene identifiedPresent

    Definitive — SLC25A15

  2. LiteraturePresent

    913 matched papers (644 in last 10 years) Source

  3. Phenotype characterisedPresent

    78 HPO annotations (e.g. Acute hepatitis; Dysmetria; Generalized myoclonic seizure) Source

  4. Animal modelNot found

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

  5. Orphan designationPartial

    2 EMA designations (none yet with FDA orphan-indication approval) — e.g. sodium benzoate Source

  6. Interventional trialNot found

    No matched interventional trial under our ClinicalTrials.gov rules

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 (SLC25A15).

GenCC classification: Definitive.

Phenotypes (Monarch / HPO)

78

Associated phenotypes · MONDO:0009393

  • Acute hepatitis
  • Dysmetria
  • Generalized myoclonic seizure
  • Cerebral cortical atrophy
  • Hypotonia

Showing 5 of 78 — 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)

2

Designations · no FDA orphan-indication approval yet

  • EMA sodium benzoate (Prohippur)Treatment of ornithine translocase deficiency · 29/08/2016 · PositiveEMA designation
  • EMA heterologous human adult liver-derived progenitor cellsTreatment of ornithine-translocase deficiency · 17/07/2013 · PositiveEMA designation

Sources: FDA OOPD · EMA orphan designations

Open Targets candidates

No drugs or clinical candidates returned for this Mondo ID on Open Targets.

CTD chemicals (MyDisease.info)

No CTD chemical associations returned for this Mondo ID.

Literature

Is anyone studying this?

913

913 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.

913 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).

644 in the last 10 years · high confidence · 85.3th percentile (publications denominator)

Phrase hits: 381 · MeSH hits: 0

Open Europe PMC search

Who's working on it?

1,369

Distinct author names in 200 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.

  1. 01
    Häberle J10 papers · 2025

    Division of Metabolism and Children`s Research Center, University Children's Hospital, Zurich, Switzerland.

    Papers in Europe PMC
  2. 02
    Kölker S10 papers · 2026

    Subnetwork for Amino and Organic Acid-Related Disorders (AOA), European Reference Network for Hereditary Metabolic Disorders (MetabERN), Udine, Italy.

    Papers in Europe PMC
  3. 03
    Dionisi-Vici C9 papers · 2024

    Subnetwork for Amino and Organic Acid-Related Disorders (AOA), European Reference Network for Hereditary Metabolic Disorders (MetabERN), Udine, Italy.

    Papers in Europe PMC
  4. 04
    Garbade SF7 papers · 2026

    Center for Pediatric and Adolescent Medicine, Division of Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany.

    Papers in Europe PMC
  5. 05
    Martinelli D7 papers · 2021

    Subnetwork for Amino and Organic Acid-Related Disorders (AOA), European Reference Network for Hereditary Metabolic Disorders (MetabERN), Udine, Italy.

    Papers in Europe PMC
  6. 06
    Hoffmann GF6 papers · 2026

    Center for Pediatric and Adolescent Medicine, Division of Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany.

    Papers in Europe PMC
  7. 07
    Schulze A6 papers · 2024

    University of Toronto and the Hospital for Sick Children, Toronto, ON, Canada.

    Papers in Europe PMC
  8. 08
    Wajner M6 papers · 2016

    Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos No 2600 - Anexo, Porto Alegre, RS, 90035-003, Brazil. mwajner@ufrgs.br.

    Papers in Europe PMC
  9. 09
    Baumgartner MR5 papers · 2020

    Division of Metabolism, Children's Research Center and University Children's Hospital Zurich, Zurich, Switzerland. matthias.baumgartner@kispi.uzh.ch.

    Papers in Europe PMC
  10. 10
    Burlina A5 papers · 2025

    Division of Inherited Metabolic Disease, University Hospital Padova, Padova, Italy.

    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.

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

No matched interventional trials. This is true for 77.2% of diseases in the trials denominator (5501 of 7126). Here are the researchers publishing on it.

high confidence · 38.6th 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.

See who's working on it — people publishing on this disease are often the practical next contact when no trial is listed.

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.

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 0 · after dedupe 0 · already on CT.gov 0 · kept 0 · parent 0 · uncertain 0 · 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).

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 Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome — check Associations / patient organisations on that page.

India — NPRD

Last verified 2026-07-26

Likely covered — the policy lists Urea cycle disorder as a category (Groups 1 and 2), and this condition is a form of it. Confirm eligibility with a Centre of Excellence.

Group 1 — one-time curative treatment

Up to ₹50 lakh per patient

Financial support for treatment at notified Centres of Excellence (figures evolved from the original ₹20 lakh Group-1 ceiling).

Policy figures change. Verify current MoHFW / CoE guidance before relying on any amount. Verify

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.

("Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome" OR "HHH syndrome" OR "ORNT1 deficiency" OR "Ornithine carrier deficiency" OR "Ornithine translocase deficiency" OR "Triple H syndrome" OR "hyperornithinemia-hyperammonemia-homocitrullinemia syndrome") OR ("SLC25A15" OR "SLC25A15 syndrome" OR "SLC25A15-related")

Run this search on Europe PMC

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

"Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome" OR "HHH syndrome" OR "ORNT1 deficiency" OR "Ornithine carrier deficiency" OR "Ornithine translocase deficiency" OR "Triple H syndrome" OR "hyperornithinemia-hyperammonemia-homocitrullinemia syndrome"

Study-type breakdown: 0 interventional · 1 observational · 0 expanded access. Only interventional studies enter the trial headline.

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 2026-07-26T13:46:43.461Z