ORPHA:927
Hyperammonemia due to N-acetylglutamate synthase deficiency
Also known as: NAGS deficiency
Clinical definition (Orphanet)
A rare disorder of urea cycle metabolism causing a deficit of ammonia detoxification and arginine synthesis, and characterized by of variable severity. Manifestations range from presentation of poor feeding, vomiting, lethargy, tachypnea, convulsions and coma to adult-onset headaches, hazy gastrointestinal symptoms, , behavioral/psychiatric problems, confusion and lethargy.
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.
Is anyone studying this?
201
201 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=183) is 38.
201 papers since the earliest indexed year in this search — median last-10-year count for a rare disease in this dataset is 38 (publications denominator n=183).
105 in the last 10 years · medium confidence · 68.3th percentile (publications denominator)
Is a treatment being tested?
1
trials for this specific condition
1 interventional trial matched this specific condition name; 1 currently recruiting in our sample.
Data as of 26 July 2026
1 interventional trial — more than 59.2% of diseases in the trials denominator have none at all (151 of 255; this disease is at the 65.3th percentile).
medium confidence · 65.3th percentile (trials denominator)
Do we know what causes it?
Yes — we know a specific gene responsible (NAGS).
GenCC classification: Definitive.
Who's working on it?
1,029
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.
- 01Tuchman M35 papers · 2021
Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA. Mtuchman@cnmc.org.
Papers in Europe PMC - 02Caldovic L26 papers · 2024
Center for Genetic Medicine Research, Children's National Medical Center, Washington, DC 20010, USA. LCaldovic@childrensnational.org.
Papers in Europe PMC - 03Morizono H16 papers · 2024
Children's Research Institute, Children's National Medical Center, The George Washington University, 111 Michigan Ave NW, Washington, DC 20010, USA.
Papers in Europe PMC - 04Häberle J15 papers · 2024
University Children's Hospital Zurich and Children's Research Centre, Zurich, 8032, Switzerland. Johannes.Haeberle@kispi.uzh.ch
Papers in Europe PMC - 05Shi D13 papers · 2018
Center for Genetic Medicine Research and Department of Integrative Systems Biology, Children's National Medical Center, The George Washington University, Washington, DC, United States of America. dshi@cnmcresearch.org
Papers in Europe PMC - 06Yudkoff M12 papers · 2021
Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA.
Papers in Europe PMC - 07Ah Mew N11 papers · 2021
Research Center for Genetic Medicine, Children's National Medical Center, George Washington University, Washington, DC 20010, USA.
Papers in Europe PMC - 08Allewell NM7 papers · 2015
Department of Cell Biology and Molecular Genetics, College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, MD 20742, USA. allewell@umd.edu.
Papers in Europe PMC - 09Nissim I7 papers · 2014
Department of Pediatrics, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, PA.
Papers in Europe PMC - 10Rubio V7 papers · 2024
Instituto de Biomedicina de Valencia del Consejo Superior de Investigaciones Científicas (IBV-CSIC), Jaime Roig 11, 46010 Valencia, Spain.
Papers in Europe PMC
Recruiting interventional trials
Trials testing a treatment from the matched ClinicalTrials.gov set
1 interventional trials matched after quoted-phrase search and title/condition post-filter.
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
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 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 below but are not added to the query string.
"Hyperammonemia due to N-acetylglutamate synthase deficiency" OR "NAGS deficiency"
MeSH descriptor terms unioned into the query: N-acetyl glutamate synthetase deficiency
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Hyperammonemia due to N-acetylglutamate synthase deficiency" OR "NAGS deficiency" OR "N-acetyl glutamate synthetase deficiency" OR "NAGS" OR "urea cycle disorder or inherited hyperammonemia"
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: 1 interventional · 3 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): MESH:C536109 OMIM:237310 UMLS:C0268543 NCIT:C129307
Query health: ok — strategies attempted: phrase, mesh, recall-expansion; with hits: phrase, mesh, recall-expansion
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
- Publication count (201) is high for prevalence class "<1 / 1 000 000" — confidence capped at medium