The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
| Signs and Symptoms | Approximate number of patients (when available) |
| Abnormality of the tongue | 90% |
| Behavioral abnormality | 90% |
| Broad-based gait | 90% |
| Cerebral cortical atrophy | 90% |
| Clumsiness | 90% |
| Cognitive impairment | 90% |
| EEG abnormality | 90% |
| Incoordination | 90% |
| Mandibular prognathia | 90% |
| Muscular hypotonia | 90% |
| Neurological speech impairment | 90% |
| Seizures | 90% |
| Sporadic | 75% |
| Abnormality of the teeth | 50% |
| Hyperreflexia | 50% |
| Malar flattening | 50% |
| Wide mouth | 50% |
| Hernia of the abdominal wall | 7.5% |
| Strabismus | 7.5% |
| Absent speech | - |
| Autosomal dominant inheritance | - |
| Blue irides | - |
| Brachycephaly | - |
| Constipation | - |
| Deeply set eye | - |
| Drooling | - |
| Exotropia | - |
| Fair hair | - |
| Feeding difficulties in infancy | - |
| Flat occiput | - |
| Hyperactivity | - |
| Hypopigmentation of the skin | - |
| Hypoplasia of the maxilla | - |
| Intellectual disability, progressive | - |
| Intellectual disability, severe | - |
| Limb tremor | - |
| Macroglossia | - |
| Motor delay | - |
| Myopia | - |
| Nystagmus | - |
| Obesity | - |
| Paroxysmal bursts of laughter | - |
| Progressive gait ataxia | - |
| Protruding tongue | - |
| Scoliosis | - |
| Sleep-wake cycle disturbance | - |
| Widely spaced teeth | - |
Several different genetic mechanisms can inactivate or delete the maternal copy of the UBE3A gene. Most cases of Angelman syndrome occur when a segment of the maternal chromosome 15 containing this gene is deleted. In other cases, Angelman syndrome is caused by a mutation in the maternal copy of the UBE3A gene.[1]
In a small percentage of cases, a person with Angelman syndrome inherits two copies of chromosome 15 from his or her father, instead of one copy from each parent. This is called paternal uniparental disomy. Rarely, Angelman syndrome can also be caused by a chromosomal rearrangement called a translocation, or by a mutation or other defect in the region of DNA that controls activation of the UBE3A gene. These genetic changes can abnormally turn off (inactivate) UBE3A or other genes on the maternal copy of chromosome 15.[1]
The cause of Angelman syndrome is unknown in 10 to 15 percent of affected individuals. Changes involving other genes or chromosomes may be responsible for the condition in these individuals.[1]Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.
Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.
Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD. Suggest an organization to add.
Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question
How is Anglemans syndrome mistaken for Autism? See answer
We have a 2-year-old son who was diagnosed with Angelman syndrome. He has a deletion of the mother's part on chromosome 15. What are the chances of this syndrome occurring in our next baby? We have another 6-year-old son who is normal. See answer
What is the chance of having another child with Angelman syndrome if a mother has a translocation of chromosomes 15 and 7? Is there additional genetic testing that could be performed? See answer
