Angelman Syndrome

Angelman syndrome facts*

*Angelman syndrome facts medically edited by: Melissa Conrad Stöppler

  • Angelman syndrome is a genetic disorder with characteristic features that include severe speech impairment, developmental delay, intellectual disability, and ataxia (problems with movement and balance).
  • Angelman syndrome is named after the physician Harry Angelman who first delineated the syndrome in 1965.
  • Angelman syndrome affects an estimated 1 in 12,000 to 20,000 people.
  • Most children with Angelman syndrome have microcephaly (small head size) and epilepsy (recurrent seizures).
  • The developmental delay of Angelman syndrome generally becomes noticeable by the age of 6 to 12 months.
  • Adults with Angelman syndrome have facial features that are distinct and are often described as "coarse."
  • Some of the characteristic features of Angelman syndrome are a result from the loss of function of a gene called UBE3A.
  • The life expectancy for individuals with Angelman syndrome appears to be nearly normal.

What is Angelman Syndrome?

Angelman syndrome is a genetic disorder that primarily affects the nervous system that causes developmental delay and neurological problems. The physician Harry Angelman first delineated the syndrome in 1965, when he described several children in his practice as having "flat heads, jerky movements, protruding tongues, and bouts of laughter."

What are the characteristics, signs, and symptoms of Angelman syndrome?

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  • Infants with Angelman syndrome appear normal at birth, but often have feeding problems in the first months of life and exhibit noticeable developmental delays by 6 to 12 months.
  • Seizures often begin between 2 and 3 years of age.
  • Speech impairment is pronounced, with little to no use of words. Individuals with this syndrome often display the following that can have severe functional deficits:
  • Children with Angelman syndrome typically have a happy, excitable demeanor with frequent smiling, laughter, and hand-flapping movements.
  • In addition to hyperactivity, a short attention span, and a fascination with water are common.
  • With age, people with Angelman syndrome become less excitable, and the sleeping problems tend to improve. However, affected individuals continue to have intellectual disability, severe speech impairment, and seizures throughout their lives.
  • Adults with Angelman syndrome have distinctive facial features that may be described as "coarse." Other common features include unusually fair skin with light-colored hair and an abnormal side-to-side curvature of the spine (scoliosis). The life expectancy of people with this condition appears to be nearly normal.

Angelman syndrome results from absence of a functional copy of the UBE3A gene inherited from the mother.


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