Kleefstra syndrome
Findings
No curated finding names Kleefstra syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
A genetic disorder characterized by intellectual disability, childhood hypotonia, severe expressive speech delay and a distinctive facial appearance with a spectrum of additional clinical features.
Definition from the Mondo Disease Ontology (MONDO:0012455), read 2026-09-29. CC BY 4.0.
Features
67 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Anteverted naresHPOHP:0000463
- Very frequent (80% to 99% of cases)
- Coarse facial featuresHPOHP:0000280
- Very frequent (80% to 99% of cases)
- Delayed speech and language developmentHPOHP:0000750
- Very frequent (80% to 99% of cases)
- Everted lower lip vermilionHPOHP:0000232
- Very frequent (80% to 99% of cases)
- Exaggerated cupid's bowHPOHP:0002263
- Very frequent (80% to 99% of cases)
- Global developmental delayHPOHP:0001263
- Very frequent (80% to 99% of cases)
- HypertelorismHPOHP:0000316
- Very frequent (80% to 99% of cases)
- HypotoniaHPOHP:0001252
- Very frequent (80% to 99% of cases)
- Malar flatteningHPOHP:0000272
- Very frequent (80% to 99% of cases)
- Severe intellectual disabilityHPOHP:0010864
- Very frequent (80% to 99% of cases)
- Short noseHPOHP:0003196
- Very frequent (80% to 99% of cases)
- Tented upper lip vermilionHPOHP:0010804
- Very frequent (80% to 99% of cases)
Show the remaining 55
- Aggressive behaviorHPOHP:0000718
- Frequent (30% to 79% of cases)
- ArrhythmiaHPOHP:0011675
- Frequent (30% to 79% of cases)
- Atypical behaviorHPOHP:0000708
- Frequent (30% to 79% of cases)
- Autistic behaviorHPOHP:0000729
- Frequent (30% to 79% of cases)
- Bicuspid aortic valveHPOHP:0001647
- Frequent (30% to 79% of cases)
- BrachycephalyHPOHP:0000248
- Frequent (30% to 79% of cases)
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- EHMT1HGNC:24650
- Definitive · ClinGen · Autosomal dominant · 2018
Where it sits
Other names
6 names
Resolves to: Kleefstra syndrome
- Also called
- 9Q- syndrome9q-syndrome9q34 deletion syndrome9q34.3 microdeletion syndromechromosome 9q deletion syndromechromosome 9Q34.3 deletion syndrome