- Related Topics:
- human genetic disease
- congenital disorder
- nervous system disease
- On the Web:
- National Center for Biotechnology Information - Angelman Syndrome (Nov. 01, 2026)
Angelman syndrome
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What is Angelman syndrome?
Angelman syndrome is a rare genetic disorder affecting the nervous system, characterized by unique symptoms first described in 1965 by English physician Harry Angelman.
The disorder is usually noticeable between 6β12 months, with infants showing an absence of crawling or babbling. By ages 2β3, seizures, ataxia, speech impairment, and intellectual disability become apparent. A hallmark of Angelman syndrome is a happy, excitable attitude with frequent smiling or laughing unrelated to the situation. Most individuals are hyperactive with a short attention span and may display unusual behaviors like hand flapping. Sleep problems are also common.
Angelman syndrome results from loss-of-function mutations in the UBE3A gene, which is essential for brain development. There is no cure, but treatments include medications, dietary therapies, and physical, occupational, and speech therapies to manage symptoms.
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What are common signs and symptoms of Angelman syndrome?
Angelman syndrome is a congenital disorder that becomes noticeable in infants around 6 to 12 months old through the absence of behaviors like babbling and crawling. Additional signs include seizures, ataxia, walking delays, speech impairment, and severe intellectual disability, which start to show around ages 2 to 3.
Those affected by Angelman syndrome often have a happy and excitable attitude, marked by frequent smiling and laughing that is often unrelated to their surroundings. Hyperactivity, a short attention span, hand flapping, and sleep problems are also common.
The symptoms of Angelman syndrome are similar to those of other disorders such as autism, Prader-Willi syndrome, and cerebral palsy, so genetic testing is needed for a definitive diagnosis.
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How does Angelman syndrome affect a person's development?
Angelman syndrome is a congenital disorder where serious signs begin to show at 6 to 12 months of age, often as an absence of babbling and crawling. At 2 to 3 years old, seizures, ataxia, and speech impairment become apparent, in addition to a delay in walking and severe intellectual disability.
Individuals with Angelman syndrome are known to have a happy and excitable attitude, frequently smiling and laughing without cause. hyperactivity and a short attention span are also common, as are unusual behaviors like hand flapping. Many also have sleep problems, though these may lessen with age.
There is no cure for Angelman syndrome, but speech, physical, and occupational therapies can help improve motor and speech skills. Though those affected need lifelong care, they have a near-typical life expectancy.
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What causes Angelman syndrome?
Angelman syndrome is a genetic disorder caused by loss-of-function mutations in the UBE3A gene. These mutations often occur as random deletions of base pairs within the gene. In rare cases, they are inherited on the maternal allele of UBE3A. UBE3A is an imprinted gene, meaning its expression is driven by the maternal allele, while the paternal allele is silenced.
The mechanism by which mutations in UBE3A result in Angelman syndrome is not fully understood. However, UBE3A expression is essential for normal brain development. The gene encodes ubiquitin protein ligase E3A, an enzyme that targets other proteins for destruction, which is critical in maintaining protein homeostasis and has an important function at synapses.
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How is Angelman syndrome diagnosed?
Angelman syndrome is a congenital disorder that becomes noticeable around 6 to 12 months with the absence of crawling and babbling. Diagnosis can be challenging because its symptoms resemble those of autism, Prader-Willi syndrome, and cerebral palsy.
A definitive diagnosis requires genetic testing. The disorder results from loss-of-function mutations in the UBE3A gene. Although there is no cure, treatments such as medication, dietary therapies, and sleep training can manage many symptoms. Physical, occupational, and speech therapies can improve motor and speech skills.
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What treatments and support are available for people with Angelman syndrome?
There is no cure for Angelman syndrome; however, therapies and interventions can help manage many of the symptoms. Infants who have feeding difficulties may need a high-calorie formula. Medication, along with dietary therapies, can help manage seizures. Medications and sleep training can help with sleep problems, which often improve with age. Hyperactivity also often decreases as the person ages.
To improve motor and speech skills, physical, occupational, and speech therapies can be beneficial. Some people learn to communicate nonverbally or with specialized devices. Because those affected by Angelman syndrome cannot live independently, they need lifelong care. A typical or near-typical life expectancy can be expected, but complications such as seizures or falls from ataxia can cause premature death.
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Angelman syndrome, rare genetic disorder that affects the nervous system. The syndrome is named for English physician Harry Angelman, who first described its characteristic symptoms in 1965 after observing children who were affected by ataxia (an inability to coordinate voluntary muscular movements) and who exhibited an unusual laughing, happy demeanor. Angelman syndrome occurs in approximately 1 in 12,000 to 1 in 20,000 live births; its incidence is suspected of being higher, however, owing to underreporting and possible misdiagnosis. The disorder affects females and males equally, and typically there is no family history of the disorder.
Symptoms
Angelman syndrome is recognized as a congenital disorder, though affected infants may only exhibit difficulties with feeding in the first few months of life. More serious signs emerge at about 6 to 12 months of age, typically as an absence of behaviors such as babbling and crawling. At about 2 to 3 years of age, affected individuals begin to experience seizures, and other symptoms, including ataxia, delayed development of walking, speech impairment, and severe intellectual disability, become apparent.
A defining characteristic of individuals with Angelman syndrome is a happy, excitable demeanor, with frequent smiling and laughing that often is unrelated to the context of what is going on around them. Most affected individuals are hyperactive and have a short attention span, and they often display unusual behaviors, such as hand flapping. Sleep problems are common, and the need for sleep may be significantly reduced.
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Cause
Angelman syndrome is caused by loss-of-function mutations in a gene known as UBE3A. Most often, these mutations occur as sporadic (random) deletions of base pairs within the gene. In rare instances, such mutations are inherited on the maternal allele of UBE3A. (UBE3A is an imprinted gene; its expression is driven by the maternal allele, while the paternal allele is silenced.)
The mechanism by which mutations in UBE3A result in Angelman syndrome is not fully understood. UBE3A expression, however, is known to be essential for normal brain development. The gene encodes ubiquitin protein ligase E3A, an enzyme that targets other proteins for destruction. This activity serves a critical role in maintaining protein homeostasis and appears to have an especially important function at synapses (junctions of communication between neurons).
Diagnosis, prognosis, and treatment
The symptoms and characteristics of Angelman syndrome are similar to those of autism, Prader-Willi syndrome, and cerebral palsy, which can lead to misdiagnosis and delayed treatment and care. Thus, genetic testing is needed to provide a definitive diagnosis of Angelman syndrome.
There is no cure for Angelman syndrome. However, many of its symptoms can be managed, and some symptoms may become less severe over time. Examples of symptom management include the use of a high-calorie formula for infants with feeding difficulties and the use of medication and dietary therapies for seizures. Sleep problems, which often lessen with age, can be treated with medications and sleep training. Hyperactivity often also decreases with age. Physical, occupational, and speech therapies can help improve motor and speech skills, and some individuals may learn to communicate nonverbally or by using specialized devices.
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Individuals with Angelman syndrome are unable to live independently and require lifelong care. Affected persons have a typical or near-typical life expectancy, though some complications, such as seizures or falls from ataxia, can cause premature death.