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Angelman Syndrome

Angelman syndrome in a 5 y Mexican Photo courtesy of Medical News TodayOpens in new window

Angelman syndrome has a prevalence of 1 in 12,000 – 24,000 and is characterized by severe intellectual disability, developmental delay, seizures, and difficulty with balance and walking.

Angelman syndrome is a complex genetic disorder of the nervous system, characterized by delayed development, severe speech impairment, intellectual disability, and problems with movement and balance (ataxia).

Angelman syndrome has a prevalence of 1 in 12,000 – 24,000; most children affected have a small head size (microcephaly) and experience recurrent seizures (epilepsy).

Delayed development becomes evident by the age of 6 to 12 months; other common signs and symptoms generally appear in early childhood. Children with Angelman syndrome typically have a happy, excitable demeanor with frequent smiling, laughter, and hand-flapping movements. Hyperactivity, a short attention span, insomnia, and a fascination with water are common.

Angelman syndrome results from abnormalities in the same gene region as Prader Willi syndromeOpens in new window but occurs due to loss of the maternal contribution, with only the paternal genes present.

This can occur from multiple genetic mechanisms that lead to lack of the maternally derived active gene, including a deletion, paternal UPD, an imprinting error, or a single-gene mutation of the maternal copy of the gene. In contrast to the mild intellectual disability seen with Prader Willi syndrome, patients with Angelman syndrome have severe developmental delay, intellectual disability, and speech impairment. Patients with Angelman syndrome also exhibit a characteristic behavioral pattern of inappropriate laughing, smiling, and excitability.

See also:
  1. Dagli AI, Mueller J, Williams CA. Angelman syndrome. Gene Rev. 2018. University of Washington, Seattle.
  2. Hiura H, Okae H, Chiba H, et al. Imprinting methylation errors in ART. Reprod Med Biol. 2014; 13(4): 193–202.
  3. Peters J. The role of genomic imprinting in biology and disease: an expanding view. Nat Rev Genet. 2014;15(8):517–530.
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