Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with EleplanKleefstra syndrome
ORPHA:261494Malformation syndrome
What it is
A rare genetic, intellectual disability syndrome characterized by intellectual disability, childhood hypotonia, severe expressive speech delay, autism spectrum disorder, and a distinctive facial appearance with a spectrum of additional clinical features.
Key facts
- Prevalence
- <1 / 1 000 000
- Age of onset
- Neonatal
- Inheritance
- Autosomal dominant
- Classified as
- Malformation syndrome
Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.
Signs and symptoms
Very common80–99%
12Common30–79%
22- Aggressive behavior
- Arrhythmia
- Atypical behavior
- Autistic behavior
- Bicuspid aortic valve
- Brachycephaly
- Broad forehead
- Chronic otitis media
- Coarctation of aorta
- Constipation
- Hearing impairment
- Highly arched eyebrow
- Macroglossia
- Mandibular prognathia
- Microcephaly
- Obesity
- Self-mutilation
- Sleep abnormality
- Synophrys
- Thickened helices
- Upslanted palpebral fissure
- Ventricular septal defect
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Genes reported in subtypes
Orphanet records these genes on 2 more specific entries under this disorder, not on this entry itself:
A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with it.
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
Powered by Eleplan
A rare diagnosis is just the start. Eleplan keeps the whole care plan in one place.
Diagnoses, medications, documents, appointments, and the whole care team — organized and always in sync, so you are not retelling the same story to every new specialist. With Ellie, your AI care assistant, on top of it. Free to start.