Angelman syndrome

Ryan W Y Lee MD (

Dr. Lee of the John A Burns School of Medicine at the University of Hawaii has no relevant financial relationships to disclose.

Michael V Johnston MD, editor. (

Dr. Johnston of Johns Hopkins University School of Medicine has no relevant financial relationships to disclose.

Originally released June 25, 2004; last updated June 12, 2020; expires June 12, 2023

This article includes discussion of Angelman syndrome and happy puppet syndrome. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Angelman syndrome is a neurodevelopmental disorder characterized by intellectual disability, epilepsy, ataxia, and a unique behavioral phenotype. In this article, the author discusses the diagnosis, prognosis, genetic counseling, and health surveillance of patients with Angelman syndrome. Also discussed are studies using models of Angelman syndrome, which provide insight into the pathoetiology and potential treatment of Angelman syndrome.

Key points


• Diagnosing Angelman syndrome has important implications for prognosis, genetic counseling, health surveillance, and, in some instances, specific symptomatic therapies.


• The number of genetic mechanisms that lead to Angelman syndrome and the paradigm for diagnostic testing has evolved as cytogenic and molecular technologies have been introduced.


• Molecular and genetic models are producing an increasingly comprehensive view of the mechanisms responsible for altered experience-dependent hippocampal and neocortical plasticity in this disorder.


• Understanding the genetic factors involved in the imprinting process has allowed researchers to target therapeutics that may show promise for treatment of this disorder.

Historical note and terminology

In 1965, Dr. Harry Angelman described 3 unrelated children who had in common severe intellectual disability, fits of laughter, ataxia, epilepsy, and similar physical features. Because of the quality of their movement, their particular facies, and the characteristic bouts of laughter, he felt they resembled “puppet children” (Angelman 1965), and further case reports referred to the condition as the “happy puppet syndrome.” In 1982, Williams and Frias suggested the eponymous “Angelman syndrome” as a less derisive-sounding alternative (Williams and Frias 1982).

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