ORPHA:2609
Isolated complex I deficiency
Also known as: Isolated NADH-CoQ reductase deficiency · Isolated NADH-coenzyme Q reductase deficiency · Isolated NADH-ubiquinone reductase deficiency · Isolated mitochondrial respiratory chain complex I deficiency
Query health: suspect — Only one of 2 strategies returned hits (phrase).
Publications
325
72.8th percentile
Trials
0
Interventional, condition-specific
Researchers
1,396
Distinct authors in sample
Gene link
SLC35G2
Limited
Readiness
2/6
Stages with a signal
Clinical definition (Orphanet)
Isolated complex I deficiency is a rare inborn error of metabolism due to mutations in nuclear or genes encoding subunits or assembly factors of the human complex I (NADH: ubiquinone oxidoreductase) and is characterized by a wide range of manifestations including marked and often fatal lactic , , leukoencephalopathy, pure and hepatopathy with tubulopathy. Among the numerous clinical phenotypes observed are Leigh syndrome, Leber optic and MELAS syndrome.
How rare: How common this is has not been clearly measured.
Cross-references
Joined from Mondo / Orphanet. MeSH labels may enter searches; UMLS / OMIM / NCIT are stored for reference.
- MONDO:0100133
- MeSH:C537475
- UMLS:C1838979
Additional Mondo synonyms (8)
NADH coenzyme Q reductase deficiency · complex 1 mitochondrial respiratory chain deficiency · isolated NADH-CoQ reductase deficiency · isolated NADH-coenzyme Q reductase deficiency · isolated NADH-ubiquinone reductase deficiency · isolated complex I deficiency · isolated mitochondrial respiratory chain complex I deficiency · mitochondrial respiratory chain complex I 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 matched interventional trial; the gene is known and literature exists — preclinical or natural-history work may still be the practical next step.
- Gene identifiedPresent
Limited — SLC35G2
- LiteraturePresent
325 matched papers (142 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 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?
Possibly — only limited evidence so far for SLC35G2.
GenCC classification: Limited.
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?
325
325 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.
325 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).
142 in the last 10 years · high confidence · 72.8th percentile (publications denominator)
Phrase hits: 325 · MeSH hits: 0
Who's working on it?
1,396
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.
- 01Taylor RW21 papers · 2025
Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
Papers in Europe PMC - 02Alston CL15 papers · 2025
Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
Papers in Europe PMC - 03Thorburn DR15 papers · 2026
From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and.
Papers in Europe PMC - 04Smeitink JA14 papers · 2016
Centre for Systems Biology and Bioenergetics, Radboud University Medical Center, Nijmegen, The Netherlands Khondrion BV, Nijmegen, The Netherlands Department of Pediatrics, Radboud Center for Mitochondrial Medicine, Radboud University Medical Center, Nijmegen, The Netherlands Jan.Smeitink@Radboudumc.nl.
Papers in Europe PMC - 05Prokisch H13 papers · 2026
Institute of Human Genetics, Technische Universität München, München, Germany.
Papers in Europe PMC - 06McFarland R12 papers · 2025
Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, UK.
Papers in Europe PMC - 07Murayama K10 papers · 2024
Department of Metabolism, Chiba Children's Hospital, 579-1 Heta-cho, Midori-ku, Chiba, 266-0007, Japan. kmuraya@mri.biglobe.ne.jp.
Papers in Europe PMC - 08Compton AG9 papers · 2021
From the Murdoch Children's Research Institute, Royal Children's Hospital and Department of Paediatrics, University of Melbourne, and alison.compton@mcri.edu.au.
Papers in Europe PMC - 09He L9 papers · 2020
Wellcome Centre for Mitochondrial Research, Newcastle University, Newcastle upon Tyne, UK.
Papers in Europe PMC - 10Willems PH9 papers · 2016
Department of Biochemistry, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands Centre for Systems Biology and Bioenergetics, Radboud University Medical Center, Nijmegen, The Netherlands.
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 on ClinicalTrials.gov (observational studies and pan-disease registries are listed separately when present).
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.
See who's working on it — people publishing on this disease are often the practical next contact when no trial is listed.
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 2026-07-26This ORPHAcode is not on our curated NPRD list (direct or Mondo-parent match). That does not decide clinical eligibility; families in India should ask a notified Centre of Excellence about current coverage.
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.
"Isolated complex I deficiency" OR "Isolated NADH-CoQ reductase deficiency" OR "Isolated NADH-coenzyme Q reductase deficiency" OR "Isolated NADH-ubiquinone reductase deficiency" OR "Isolated mitochondrial respiratory chain complex I deficiency" OR "NADH coenzyme Q reductase deficiency" OR "complex 1 mitochondrial respiratory chain deficiency" OR "mitochondrial respiratory chain complex I deficiency"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Isolated complex I deficiency" OR "Isolated NADH-CoQ reductase deficiency" OR "Isolated NADH-coenzyme Q reductase deficiency" OR "Isolated NADH-ubiquinone reductase deficiency" OR "Isolated mitochondrial respiratory chain complex I deficiency" OR "NADH coenzyme Q reductase deficiency" OR "complex 1 mitochondrial respiratory chain deficiency" OR "mitochondrial respiratory chain complex I deficiency" OR "SLC35G2" OR "mitochondrial respiratory chain complex deficiency"
Recall-expansion terms: SLC35G2, mitochondrial respiratory chain complex deficiency
Study-type breakdown: 0 interventional · 0 observational · 0 expanded access. Only interventional studies enter the trial headline.
Query health: suspect — strategies attempted: phrase, recall-expansion; 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 2026-07-26T20:40:26.296Z