Table 2.

Angelman Syndrome: Frequency of Select Features

Feature% of Persons with FeatureComment
Seizures90%Many seizure types; nonconvulsive status epilepticus in 20%
Nonepileptic myoclonus20%More common in adults
Sleep problems80%-90%Frequent awakening, dyssomnias, irregular sleep-wake cycles
Behavioral features100%Hypermotoric activity, oral exploration, frequent smiling & laughter, aggression, anxiety, autism spectrum traits
Motor delay / tremor100%
Language delay /
Cognitive impairment		100%Persons mosaic for imprinting center defects demonstrate better language development.
Feeding/GI issues85%
Microcephaly 125%-80%Apparent by age 2 yrs; most common in those w/15q11.2-q13 deletion
Characteristic facial features<80%Flat occiput, occipital groove, wide mouth, widely spaced teeth, protruding tongue, & prognathia; ± light hair, skin, & eyes
Strabismus40%-50%
Scoliosis≤50%Children: 10%-30%; adults: 30%-50%

GI = gastrointestinal

1.

Normal occipital frontal circumference should not exclude AS diagnosis.

From: Angelman Syndrome

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