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Start free with EleplanAngelman syndrome
ORPHA:72Malformation syndrome
What it is
A rare genetic neurodevelopmental disorder characterized by moderate to severe intellectual disability, microcephaly, seizures, ataxic gait and distinct abnormal facial shape.
Key facts
- Prevalence
- 1-9 / 100 000
- Age of onset
- Infancy
- Inheritance
- Not applicable
- 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%
19- Abnormality of speech or vocalization
- Ataxia
- Atypical behavior
- Autistic behavior
- Broad-based gait
- Cerebral cortical atrophy
- Delayed speech and language development
- EEG abnormality
- Hyperactivity
- Inappropriate laughter
- Intellectual disability, severe
- Microcephaly
- Motor delay
- Poor speech
- Seizure
- Self-injurious behavior
- Severe global developmental delay
- Sleep abnormality
- Tremor
Common30–79%
19- Abnormal facial shape
- Abnormality of the gastrointestinal tract
- Astigmatism
- Constipation
- Drooling
- Fair hair
- Feeding difficulties
- Floppy infant
- Gastroesophageal reflux
- Hypopigmentation of the skin
- Iris hypopigmentation
- Obesity
- Polyphagia
- Protruding tongue
- Recurrent hand flapping
- Scoliosis
- Sleep-wake cycle disturbance
- Strabismus
- Wide mouth
Sometimes5–29%
32- Absent speech
- Aggressive behavior
- Amblyopia
- Anxiety
- Atonic seizure
- Atypical absence seizure
- Cerebral dysmyelination
- Delayed menarche
and 24 more in this range
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 4 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.
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