ORPHA:261494
Kleefstra syndrome
Clinical definition (Orphanet)
A rare genetic, syndrome characterized by , childhood , severe expressive speech delay, autism spectrum disorder, and a distinctive facial appearance with a spectrum of additional clinical features.
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?
751
751 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=183) is 38.
751 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).
589 in the last 10 years · low confidence
Is a treatment being tested?
0
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 26 July 2026
No matched interventional trials. This is true for 59.2% of diseases in the trials denominator (151 of 255). Here are the researchers publishing on it.
low confidence · 29.6th percentile (trials denominator)
Do we know what causes it?
Yes — we know a specific gene responsible (EHMT1).
GenCC classification: Definitive.
Who's working on it?
1,379
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.
- 01Kleefstra T24 papers · 2026
Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud university medical center, Nijmegen, The Netherlands.
Papers in Europe PMC - 02Bouman A13 papers · 2026
Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.
Papers in Europe PMC - 03Rots D10 papers · 2026
Department of Human Genetics, Radboudumc, Nijmegen, The Netherlands.
Papers in Europe PMC - 04Sadikovic B9 papers · 2026
Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, Ontario, Canada.
Papers in Europe PMC - 05Srivastava S8 papers · 2026
Department of Neurology, Boston Children's Hospital, Boston, MA, USA.
Papers in Europe PMC - 06Kerkhof J7 papers · 2026
Verspeeten Clinical Genome Centre, London Health Sciences Centre, London, Ontario, Canada.
Papers in Europe PMC - 07Kummeling J7 papers · 2026
Department of Human Genetics, Donders Institute for Brain, Cognition and Behavior, Radboud university medical center, Nijmegen, The Netherlands.
Papers in Europe PMC - 08Negwer M6 papers · 2026
Department of Human Genetics and Department of Cognitive Neuroscience, Radboudumc, Donders Institute for Brain, Cognition and Behaviour, 6500 HB Nijmegen, Netherlands.
Papers in Europe PMC - 09Banka S5 papers · 2026
Division of Evolution, Infection & Genomics, School of Biological Sciences, Faculty of Biology, Medicine & Health, The University of Manchester, Manchester M13 9PL, UK.
Papers in Europe PMC - 10Barrero MJ5 papers · 2026
Institute of Rare Diseases Research (IIER), Spanish National Institute of Health Carlos III (ISCIII), Madrid, Spain.
Papers in Europe PMC
Recruiting interventional trials
Trials testing a treatment 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 above — 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.
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 2026-07-26This 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 below but are not added to the query string.
"Kleefstra syndrome" OR "9Q- syndrome" OR "9q-syndrome" OR "9q34 deletion syndrome" OR "9q34.3 microdeletion syndrome" OR "chromosome 9Q34.3 deletion syndrome" OR "chromosome 9q deletion syndrome"
ClinicalTrials.gov query (quoted phrases + MeSH via query.cond, plus recall-expansion terms when used):
"Kleefstra syndrome" OR "9Q- syndrome" OR "9q-syndrome" OR "9q34 deletion syndrome" OR "9q34.3 microdeletion syndrome" OR "chromosome 9Q34.3 deletion syndrome" OR "chromosome 9q deletion syndrome" OR "EHMT1"
Study-type breakdown: 0 interventional · 1 observational · 0 expanded access. Only interventional studies enter the trial headline.
Cross-references (from Mondo): UMLS:C4551771
Query health: ok — strategies attempted: phrase, recall-expansion; with hits: phrase, recall-expansion
Run this search on ClinicalTrials.gov
Confidence reasoning
- Preferred label is short or not clearly distinctive
- No synonyms dropped by stoplist
- No label/synonym collisions with other diseases in this corpus
- Publication count (751) is implausibly high for prevalence class "<1 / 1 000 000" — treat as possible over-matching, not a measure of research intensity