Angelman syndrome is a genetic disorder. It causes delayed development, problems with speech and balance, intellectual disability, and, sometimes, seizures.

People with Angelman syndrome often smile and laugh frequently, and have happy, excitable personalities.

Developmental delays, which begin between about 6 and 12 months of age, are usually 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 normal life span, but the disorder can't be cured. Treatment focuses on managing medical, sleep and developmental issues.


Angelman syndrome signs and symptoms include:

  • Developmental delays, including no crawling or babbling at 6 to 12 months
  • Intellectual disability
  • No speech or minimal speech
  • Difficulty walking, moving or balancing well
  • Frequent smiling and laughter
  • Happy, excitable personality
  • Sucking or feeding difficulty
  • Trouble going to sleep and staying asleep

People who have Angelman syndrome may also show the following features:

  • Seizures, usually beginning between 2 and 3 years of age
  • Stiff or jerky movements
  • Small head size, with flatness in the back of the head
  • Tongue thrusting
  • Hair, skin and eyes that are light in color
  • Unusual behaviors, such as hand flapping and arms uplifted while walking
  • Sleep problems
  • Curved spine (scoliosis)

When to see a doctor

Most babies with Angelman syndrome don't show signs or symptoms at birth. The first signs of Angelman syndrome are usually developmental delays, such as lack of crawling or babbling, between 6 and 12 months.

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


Angelman syndrome is a genetic disorder. It's usually caused by problems with a gene located on chromosome 15 called the ubiquitin protein ligase E3A (UBE3A) gene.

A missing or defective gene

You receive your pairs of genes from your parents — one copy from your mother (maternal copy) and the other from your father (paternal copy).

Your cells typically use information from both copies, but in a small number of genes, only one copy is active.

Normally, only the maternal copy of the UBE3A gene is active in the brain. Most cases of Angelman syndrome occur when part of the maternal copy is missing or damaged.

In a few cases, Angelman syndrome is caused when two paternal copies of the gene are inherited, instead of one from each parent.

Risk factors

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

Occasionally, Angelman syndrome may be inherited from a parent. A family history of the disease may increase a baby's risk of developing Angelman syndrome.


Complications associated with Angelman syndrome include:

  • Feeding difficulties. Difficulty coordinating sucking and swallowing may cause feeding problems in infants. Your pediatrician may recommend 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, and medication usually isn't necessary.
  • Sleep disorders. People with Angelman syndrome often have abnormal sleep-wake patterns and may require less sleep than most people. Sleep difficulties may improve with age. Medication and behavior therapy may help control sleep disorders.
  • Curvature of the spine (scoliosis). Some people with Angelman syndrome develop an abnormal side-to-side spinal curvature over time.
  • Obesity. Older children with Angelman syndrome tend to have large appetites, which may lead to obesity.


In rare cases, Angelman syndrome may be passed from an affected parent to a child through defective genes. If you're concerned about a family history of Angelman syndrome or if you already have a child with the disorder, consider talking to your doctor or a genetic counselor for help planning future pregnancies.

Angelman syndrome care at Mayo Clinic

March 01, 2022
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