ORPHA:254875
TK2-related mitochondrial DNA maintenance defect, myopathic form
Also known as: TK2 deficiency · Thymidine kinase 2 deficiency · TK2d
Query health: suspect — Only one of 3 strategies returned hits (phrase).
Publications
204
74.1th percentile
Trials
4
Interventional, condition-specific
Researchers
1,119
Distinct authors in sample
Gene link
TK2
Definitive
Readiness
3/6
Stages with a signal
Clinical definition (Orphanet)
A rare DNA depletion syndrome characterized by muscle weakness, and , generalized due to depletion of mtDNA in skeletal muscles. Clinical progression ranges from rapid and early fatal course due to respiratory failure, to slowly over the course of childhood or even early adulthood.
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:0012301
- MeSH:C563698
- OMIM:609560
- UMLS:C3149750
Additional Mondo synonyms (2)
mitochondrial DNA depletion syndrome type 2 · mtDNA depletion syndrome, myopathic form
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.”
3/6 stages with a signal
An interventional trial matched this condition name on ClinicalTrials.gov — see trials below.
- Gene identifiedPresent
Definitive — TK2
- LiteraturePresent
204 matched papers (151 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 trialPresent
4 matched on ClinicalTrials.gov (1 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 (TK2).
GenCC classification: Definitive.
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?
204
204 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.
204 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).
151 in the last 10 years · medium confidence · 74.1th percentile (publications denominator)
Phrase hits: 204 · MeSH hits: 0
Who's working on it?
1,119
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.
- 01Hirano M35 papers · 2026
Department of Neurology, Columbia University Medical Center, New York, New York, USA.
Papers in Europe PMC - 02Domínguez-González C17 papers · 2026
Neuromuscular Unit, Department of Neurology, Hospital Universitario 12 de Octubre, 28041 Madrid, Spain.
Papers in Europe PMC - 03
- 04Garone C10 papers · 2026
Department of Medical and Surgical Sciences, Alma Mater Studiorum University of Bologna, 40138 Bologna, Italy; UOC Neuropsichiatria dell'età Pediatrica, IRCCS Istituto delle Scienze Neurologiche di Bologna, 40138 Bologna, Italy. Electronic address: caterina.garone@unibo.it.
Papers in Europe PMC - 05Martí R10 papers · 2026
Laboratory of Mitochondrial Disorders, Institut de Recerca Hospital Universitari Vall d'Hebron, 08035 Barcelona, Spain.
Papers in Europe PMC - 06Nascimento A10 papers · 2026
Center for Biomedical Network Research on Rare Diseases (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.
Papers in Europe PMC - 07Zhou X9 papers · 2023
Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institute, Karolinska University Hospital, Stockholm 141 86, Sweden.
Papers in Europe PMC - 08Paradas C8 papers · 2026
Neuromuscular Disorders Unit, Neurology Department, Hospital Universitario Virgen del Rocío, Sevilla, Spain.
Papers in Europe PMC - 09Scaglia F8 papers · 2026
Department of Molecular and Human Genetics, Baylor College of Medicine and Texas Children's Hospital, Houston, Texas, USA.
Papers in Europe PMC - 10Vilà MR7 papers · 2011
Department of Neurology, Columbia University College of Physicians & Surgeons. New York, NY, USA.
Papers in Europe PMC
Clinical research
Is a treatment being tested?
4
interventional trials for this specific condition
4 interventional trials matched this specific condition name; 1 currently recruiting in our sample.
Data as of 27 July 2026
4 interventional trials — more than 73% of diseases in the trials denominator have none at all (5114 of 7003; this disease is at the 86.7th percentile).
medium confidence · 86.7th percentile (trials denominator)
Recruiting interventional trials
From the matched ClinicalTrials.gov set
4 interventional trials matched after quoted-phrase search and title/condition post-filter.
- NCT06754098·RECRUITING·Doxecitin and Doxribthymine in Adult Subjects With Thymidine Kinase 2 (TK2) Deficiency
Conditions: Thymidine Kinase 2 (TK2 ) Deficiency · Mitochondrial Myopathies·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 2026-07-26This 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.
"TK2-related mitochondrial DNA maintenance defect, myopathic form" OR "TK2 deficiency" OR "Thymidine kinase 2 deficiency" OR "mitochondrial DNA depletion syndrome type 2" OR "mtDNA depletion syndrome, myopathic form"
MeSH descriptor terms unioned into the query: Mitochondrial DNA Depletion Syndrome, Myopathic Form
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"TK2-related mitochondrial DNA maintenance defect, myopathic form" OR "TK2 deficiency" OR "Thymidine kinase 2 deficiency" OR "mitochondrial DNA depletion syndrome type 2" OR "mtDNA depletion syndrome, myopathic form" OR "Mitochondrial DNA Depletion Syndrome, Myopathic Form" OR "TK2"
Recall-expansion terms: TK2
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: 4 interventional · 1 observational · 0 expanded access. Only interventional studies enter the trial headline.
Query health: suspect — strategies attempted: phrase, mesh, recall-expansion; with hits: phrase
Run this search on ClinicalTrials.gov
Synonyms dropped by stoplist: TK2d
Confidence reasoning
- Preferred label is multi-word and distinctive
- 1 synonym(s) dropped by stoplist (may under-count)
- No label/synonym collisions with other diseases in this corpus
Ingested 2026-07-27T11:07:54.569Z