Angelman syndrome is a condition caused by a change in a gene, called a genetic change. Angelman syndrome causes delayed development, problems with speech and balance, mental disability, and, sometimes, seizures.

Many people with Angelman syndrome smile and laugh often. They tend to be happy and easy to excite.

Delays in maturing, called developmental delays, begin between about 6 and 12 months of age. The delays often are the first signs of Angelman syndrome. Seizures may begin between the ages of 2 and 3 years old.

People with Angelman syndrome tend to live close to a typical life span. But the condition can't be cured. Treatment focuses on managing medical, sleep and developmental issues.


Angelman syndrome symptoms include:

  • Developmental delays, including no crawling or babbling at 6 to 12 months.
  • Mental disability, also called intellectual disability.
  • No speech or little speech.
  • Trouble walking, moving or balancing.
  • Smiling and laughing often and seeming happy.
  • Being easy to excite.
  • Trouble sucking or feeding.
  • Trouble going to sleep and staying asleep.

People who have Angelman syndrome also may have:

  • Seizures, often beginning between 2 and 3 years of age.
  • Stiff or jerky movements.
  • Small head size by age 2.
  • Tongue thrusting.
  • Hair, skin and eyes that are light in color.
  • Odd behaviors, such as hand flapping and arms uplifted while walking.
  • Crossed eyes, also caused strabismus.
  • Curved spine, also called scoliosis.

When to see a doctor

Most babies with Angelman syndrome don't show symptoms at birth. The first signs of Angelman syndrome most often are developmental delays. This includes lack of crawling or babbling between 6 and 12 months.

If your child seems to have developmental delays or if your child has other symptoms of Angelman syndrome, make an appointment with your child's healthcare professional.


Angelman syndrome is caused by changes in a gene, called a genetic change. It's most often caused by changes in a gene on chromosome 15 called the ubiquitin protein ligase E3A (UBE3A) gene.

A missing or damaged gene

You receive your pairs of genes from your parents. One copy comes from your mother, called the maternal copy. The other comes from your father, called the paternal copy.

Your cells most often use information from both copies. But in a small number of genes, such as the UBE3A gene, only the copy from the mother is active.

Most often, the maternal copy of the UBE3A gene helps the brain develop. Angelman syndrome happens when part of the maternal copy is missing or damaged. So the brain can't get the information it needs to develop and control speech and movement.

Rarely, Angelman syndrome is caused when two paternal copies of the gene are passed down instead of one from each parent.

Risk factors

Angelman syndrome is rare. Researchers often don't know what causes the genetic changes that result in the disease. Most people with Angelman syndrome don't have a family history.

But sometimes Angelman syndrome may be passed down from a parent. A family history of the disease may increase a baby's risk of getting Angelman syndrome.


Complications linked to Angelman syndrome include:

  • Trouble feeding. Trouble sucking and swallowing together may cause feeding problems in infants. Your child's healthcare professional may suggest a high-calorie formula to help your baby gain weight.
  • Hyperactivity. Children with Angelman syndrome often move quickly from one activity to another, have a short attention span, and keep their hands or a toy in their mouths. Hyperactivity often decreases with age. Medicine often isn't needed.
  • Sleep troubles. People with Angelman syndrome often have changes in their sleep-wake patterns. They may need less sleep than most people. Sleep troubles may improve with age. Medicine and behavior therapy may help.
  • Curving of the spine, also called scoliosis. Some people with Angelman syndrome get a side-to-side spinal curve over time.
  • Obesity. Obesity is common in older children with Angelman syndrome.


Rarely, Angelman syndrome may be passed from an affected parent to a child through changed genes. If you're concerned about a family history of Angelman syndrome or if you have a child with the condition, seek medical advice. Your healthcare professional or a genetic counselor can help you plan future pregnancies.

March 08, 2024
  1. Angelman syndrome information page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/angelman-syndrome#. Accessed Nov. 3, 2023.
  2. AskMayoExpert. Angelman syndrome. Mayo Clinic; 2023.
  3. What is Angelman syndrome: Diagnosis. Angelman Syndrome Foundation. https://www.angelman.org/what-is-as/. Accessed Nov. 3, 2023.
  4. Adam MP, et al., eds. Angelman syndrome. In: Gene Reviews. University of Washington, Seattle; 1993-2023. https://www.ncbi.nlm.nih.gov/books/NBK1116. Accessed Nov. 3, 2023.
  5. Maranga C, et al. Angelman syndrome: A journey through the brain. The FEBS Journal. 2020; doi:10.1111/febs.15258.
  6. Ami T. Allscripts EPSi. Mayo Clinic. Nov. 14, 2023.


Products & Services