Angelman Syndrome

Also known as

Angelman Syndrome is a neurogenetic disorder affecting around 1 in 12-24,000 live births. It is caused by one of several different types of disruptions to a region of chromosome 15, specifically the single gene, UBE3A.

Condition details

Angelman Syndrome is characterised by severe learning difficulties, ataxia, seizures, a characteristic EEG, subtle dysmorphic facial features, and a happy, sociable disposition. Most children present with delay in developmental milestones and slowing of head growth during the first year of life. In the majority of cases speech does not develop or is severely limited. Individuals with AS have a characteristic behavioural phenotype with jerky movements, frequent and sometimes inappropriate laughter, a love of water, and poor sleep. The facial features are subtle and include a wide, smiling mouth, prominent chin, and deep set eyes. It is caused by a variety of genetic abnormalities involving the chromosome 15q11-13 region, which is subject to genomic imprinting. These include maternal deletion, paternal uniparental disomy, imprinting defects, and point mutations or small deletions within the UBE3A gene, which lies within this region.

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Photos of affected individuals

Click images to enlarge.

  • No baby imageBaby
  • No toddler imageToddler
  • No child 4-10 imageChild 4-10
  • No child 10-18 imageChild 10-18
  • No adult imageAdult

Typical age range of first manifestation

  • Can manifest in Baby
  • Can manifest in Toddler
  • Does not manifest in Child 4-10
  • Does not manifest in Child 10-18
  • Does not manifest in Adult


Lay terms Clinical terms
  • Feeding difficulties seen in the majority of infants. Suck ineffective and breast feeding may be problematic Gastro-oesophageal reflux. Constipation often caused by inadequate fluid intake.
Lay terms Clinical terms
  • Severe developmental delay Movement disorder Unique behaviour Impaired head growth Seizures Abnormal EEG Abnormal sleep pattern Abnormal food related behaviours Fascination with water Constipation Scoliosis

Affected genes identified to date

  • UBE3A

Inheritance patterns

Are carriers affected?


How many are affected?

Approx 1:12,000 to 1:24,000

Support groups and organisations

Ms Rachel Martin
PO Box 4962
CV11 9FD
Tel 0300 999 0102

Known experts

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