What is the prevalence of seizures in Angelman syndrome?

Updated: May 30, 2019
  • Author: David Y Ko, MD; Chief Editor: Selim R Benbadis, MD  more...
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Angelman syndrome is an inherited disorder that is most frequently (68%) caused by a deletion in the maternally inherited region of chromosome 15q11.2-q13. Approximately 7% of cases are caused by paternal disomy of the same region. An additional 11% of cases of Angelman syndrome are due to sequence variants in the maternally inherited UBE3A gene.

Patients with Angelman syndrome generally have a normal prenatal and birth history, with the first evidence of developmental delay occurring between 6 and 12 months of age. Seizures occur in over 80% of patients with Angelman syndrome, with onset before age 3 years.

Patients generally have deceleration of head growth, resulting in microcephaly by early childhood. Dysmorphic facies are typical and include a protruding tongue, prognathia, and a wide mouth with widely-spaced teeth. Patients with a deletion also have hypopigmentation. Intellectual impairments are typically severe and speech impairment is quite severe, with most patients having few or no words. Patients also have ataxia and frequent laughter with a happy demeanor.

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