Angelman Syndrome
A genetic condition affecting development, movement, and speech
Quick Facts
- Type: Genetic neurological condition
- Common cause: Loss of UBE3A gene function
- Key features: Developmental delay, limited speech, seizures
- Manner: Frequent smiling and laughter
Overview
Angelman syndrome is a genetic condition that affects the nervous system and brain development. It causes significant developmental delay, little or no speech, problems with movement and balance, and often a distinctive happy, excitable manner with frequent smiling and laughter. Seizures and a small head size are also common.
The condition is caused by the loss of function of a gene called UBE3A. Signs usually become noticeable in the first year or two of life, often beginning with delayed development. Angelman syndrome is a lifelong condition, but with therapies, seizure management, and supportive care, many people make progress in skills and enjoy a good quality of life. Care is best coordinated by a team of specialists.
Symptoms
Features of Angelman syndrome typically include:
- Delayed development, becoming noticeable around 6 to 12 months of age
- Severe limitations in speech, with little or no use of words; communication often relies on gestures and devices
- Problems with movement and balance, including a stiff or jerky walk and unsteadiness
- A frequently happy demeanor, with smiling, laughter, and excitability
- Hand-flapping and other repetitive movements
- Seizures, usually beginning in early childhood
- A small head size and, in some children, sleep difficulties and feeding problems
Intelligence and abilities vary, and many individuals understand more than they can express.
Causes
Angelman syndrome is caused by the loss of normal function of the UBE3A gene, which is needed for healthy brain development. In the brain, only the copy of this gene inherited from the mother is normally active. The condition develops when that maternal copy is missing or not working. This can happen in several ways:
- Deletion: A missing segment of the maternal chromosome containing the gene, the most common cause.
- Gene mutation: A change within the UBE3A gene itself.
- Other genetic mechanisms: Less common causes involving how the gene is inherited or switched on.
Most cases occur by chance, though the underlying mechanism affects the chance of it happening again in a family.
Risk Factors
- Most cases occur sporadically, without a family history
- The specific genetic mechanism influences the chance of recurrence in a family
- There are no known behaviors or exposures during pregnancy that cause it
Genetic counseling is helpful for families to understand the cause and any chance of recurrence.
Diagnosis
Angelman syndrome is diagnosed based on its characteristic features and confirmed with genetic testing:
- Clinical evaluation: Recognizing the pattern of developmental delay, limited speech, movement difficulties, and the distinctive happy manner.
- Genetic testing: Specialized tests that examine the UBE3A gene region to identify deletions, mutations, or other mechanisms.
- Additional assessments: Brain wave testing for seizures, developmental evaluation, and ruling out conditions with overlapping features.
Treatment
There is no cure, so treatment focuses on managing symptoms and supporting development, typically with a team of specialists. Care may include:
- Therapies: Physical therapy for movement and balance, occupational therapy for daily skills, and communication therapy, often using gestures, pictures, or communication devices.
- Seizure management: Medications to control seizures, which are common in Angelman syndrome.
- Sleep and behavior support: Strategies and, when needed, treatments for sleep difficulties.
- Feeding and nutrition support: Help with feeding and growth when needed.
- Ongoing care: Regular monitoring of development, the spine, and overall health, with support for families.
When to See a Doctor
Talk to your child's doctor if your child has delayed development, is not babbling or speaking as expected, has problems with movement or balance, or shows the distinctive features of Angelman syndrome. Early evaluation allows for genetic testing and helps connect the family with supportive services.
Children with Angelman syndrome need regular follow-up. Seek emergency care for:
- A first seizure, or a seizure lasting more than five minutes
- Repeated seizures without full recovery in between
- Difficulty breathing, choking, or a bluish color
- Signs of serious illness or dehydration
Frequently Asked Questions
What causes Angelman syndrome?
It is caused by the loss of normal function of the UBE3A gene, which is needed for brain development. In the brain, only the copy inherited from the mother is active, so the condition develops when that copy is missing or not working, most often due to a missing chromosome segment.
Is Angelman syndrome inherited?
Most cases occur by chance rather than being passed down. However, the specific genetic mechanism affects the chance of it happening again in a family, so genetic counseling is recommended to understand the cause and recurrence risk.
Why do people with Angelman syndrome smile and laugh often?
A frequently happy, excitable manner with smiling and laughter is one of the characteristic features of the condition and relates to how it affects the nervous system. It is part of the recognizable pattern doctors look for when making a diagnosis.
Can Angelman syndrome be treated?
There is no cure, but symptoms can be managed. Treatment includes physical, occupational, and communication therapies, seizure medications, and support for sleep, feeding, and behavior. Many individuals make progress in skills with consistent, coordinated care.
How do people with Angelman syndrome communicate?
Most have little or no spoken language but often understand more than they can express. Communication usually relies on gestures, pictures, and communication devices, and speech-language support helps maximize each person's ability to communicate.
References
- National Institute of Neurological Disorders and Stroke (NINDS).
- National Institutes of Health (NIH), Genetic and Rare Diseases Information Center (GARD).
- MedlinePlus, U.S. National Library of Medicine. Angelman syndrome.
- Angelman Syndrome Foundation.