Angelman syndrome is a complex neurological genetic disorder affecting about 1 in 15,000 people. The disorder, which causes physical and intellectual disabilities, was first identified more than 50 years ago by an English physician, Harry Angelman, who noticed similar symptoms in several of his pediatric patients.
In 1965, he started diagnosing these patients with a new illness he called “happy puppet syndrome” due to the children’s cheerful nature and mechanical, puppet-like movements.
The disorder was renamed Angelman syndrome in 1982. As genetic research has advanced in recent decades, physicians and scientists have been able to better understand the characteristics and causes of Angelman syndrome.
What causes Angelman syndrome?
Angelman syndrome is not a hereditary disease, meaning it is not usually passed from parents to their biological children. The genetic defect responsible typically develops by chance after conception, when the UBE3A gene — also known as the Angelman gene — is missing or malfunctions.
A person generally receives one copy of the UBE3A gene from each biological parent. In most body tissues, both copies of the UBE3A gene are active, but in certain parts of the brain, only the UBE3A gene inherited from the biological mother is active.
In the majority of Angelman cases, part of the maternal chromosome 15 where the UBE3A gene is found is missing. In a smaller percentage of cases, the maternal chromosome 15 may be present but inactive, or the patient may have inherited two copies of chromosome 15 from their biological father (and none from their mother), a very rare biological phenomenon called uniparental disomy. In other cases, the UBE3A gene may have mutations that alter its genetic code, impairing its function. In all of these cases, the maternal UBE3A gene required for certain neurologic functions is unavailable, ultimately causing the disease.
How does Angelman syndrome affect the body?
The first signs of Angelman syndrome usually are detected between the ages of 6 to 12 months, with babies showing delayed physical and mental development. Because early symptoms are fairly nonspecific, it is common for children with Angelman to be initially misdiagnosed with more prevalent conditions like autism or cerebral palsy.
Children with Angelman typically smile and laugh frequently, often for no apparent reason, and they tend to sleep less than is typical for children of their age. Most people with Angelman have little or no ability to speak, but are able to meaningfully communicate through other means.
As they grow, children generally commonly experience coordination issues and seizures. Restlessness, short attention spans, scoliosis — an abnormal curvature of the spine — coarse facial features, and a particular fascination with water also are common disease indicators.
How is the disorder diagnosed?
A diagnosis of Angelman is usually first suspected due to behavioral and developmental abnormalities, particularly the combination of lacking speech, movement difficulties, and an unusually happy demeanor. Various clinical assessments, such as electroencephalogram (EEG) and magnetic resonance imaging (MRI), may help to identify characteristic features of the syndrome, or to rule out other conditions with similar symptoms.
Genetic testing to identify aberrations in the UBE3A gene that cause Angelman syndrome can aid in making a definitive diagnosis.
What is the appropriate care for Angelman patients?
Angelman syndrome currently has no cure. People with the condition live a normal lifespan, but most have learning difficulties and limited speech capabilities that necessitate some level of consistent care throughout their lives. Many adults with Angelman live independently from their families — either in their own homes with support, or in a residential or care environment — and have active social lives and roles in their communities.
Medications can help to control potentially injurious symptoms like seizures. Physical and occupational therapies can aid patients with motor difficulties, while behavioral therapy and communication aids can help to improve interpersonal difficulties.
Experimental treatments in clinical trials are now underway to address seizures and other health problems, and research is ongoing to potentially restore the function of the UBE3A gene in patients’ brains.
Last updated: May 19, 2021
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