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Angelman syndrome

Angelman syndrome (AS) is a genetic condition that causes problems with the way a child's body and brain develop. The syndrome is present from birth (congenital). However, it often isn't diagnosed until about 6 to 12 months of age. This is when development problems are first noticed in most cases.

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Causes

This condition involves the gene UBE3A.

Most genes come in pairs. Children receive one from each parent. In most cases, both genes are active. This means information from both genes is used by the cells. With the UBE3A gene, both parents pass it on, but only the gene passed on from the mother is active.

Angelman syndrome most often occurs because the UBE3A gene passed on from the mother doesn't work the way it should. In some cases, AS is caused when two copies of the UBE3A gene come from the father, and none come from the mother. This means neither gene is active, because they both come from the father.

Symptoms

In newborns and infants:

• Loss of muscle tone (floppiness)
• Trouble feeding
• Heartburn (acid reflux)
• Trembling arm and leg movements

In toddlers and older children:

• Unstable or jerky walking
• Little or no speech
• Happy, excitable personality
• Laughing and smiling often
• Light hair, skin, and eye color compared to rest of family
• Small head size compared to body, flattened back of head
• Severe intellectual disability
• Seizures
• Excessive movement of the hands and limbs
• Sleep problems
• Tongue thrusting, drooling
• Unusual chewing and mouthing movements
• Crossed eyes
• Walking with arms uplifted and hands waving

Most children with this disorder don't show symptoms until about 6 to 12 months. This is when parents may notice a delay in their child's development, such as not crawling or starting to talk.

Children between 2 and 5 years of age start to show symptoms such as jerky walking, happy personality, laughing often, no speech, and intellectual problems.

Exams and Tests

Genetic tests may diagnose Angelman syndrome. These tests look for:

• Missing pieces of chromosomes
• Specific DNA to see if copies of the gene from both parents are in an inactive or active state
• A gene variant in the copy of the gene inherited from the mother

Other tests may include:

• Brain MRI
• EEG
  

Treatment

There is no cure for Angelman syndrome. Treatment helps to manage health and development problems caused by the condition.

• Anticonvulsant medicines help control seizures
• Behavior therapy helps manage hyperactivity, sleep problems, and development problems
• Occupational and speech therapy manage speech problems and teach living skills
• Physical therapy helps with walking and movement problems
  

Support Groups

More information and support for people with Angelman syndrome and their families can be found at:

• Angelman Syndrome Foundation -- www.angelman.org
• AngelmanUK -- www.angelmanuk.org

Outlook (Prognosis)

People with AS live close to a normal lifespan. Many have friendships and interact socially. Treatment helps improve function. People with AS can't live on their own. However, they may be able to learn certain tasks and live with others in a supervised setting.

Possible Complications

Complications may include:

• Severe seizures
• Gastroesophageal reflux (heartburn)
• Scoliosis (curved spine)
• Accidental injury due to uncontrolled movements

When to Contact a Medical Professional

Contact your health care provider if your child has symptoms of this condition.

Prevention

There is no way to prevent Angelman syndrome. If you have a child with AS or a family history of the condition, you may want to talk with your provider before becoming pregnant.

References

Kumar V, Abbas AK, Aster JC, Deyrup AT, Das A. Genetic and pediatric diseases. In: Kumar V, Abbas AK, Aster JC, Devrup AT, Das A, eds. Robbins & Kumar Basic Pathology. 11th ed. Philadelphia, PA: Elsevier; 2023:chap 4.

Madan-Khetarpal S, Arnold G, Ortiz D. Genetic disorders and dysmorphic conditions. In: Zitelli BJ, McIntire SC, Nowalk AJ, Garrison J, eds. Zitelli and Davis' Atlas of Pediatric Physical Diagnosis. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 1.

Yimaz F, Beck CR, Lee C. The chromosomal and genomic basis of disease: disorders of the autosomes and sex chromosomes. In: Cohn RD, Scherer SW, Hamosh A, eds. Thompson & Thompson Genetics and Genomics in Medicine. 9th ed. Philadelphia, PA: Elsevier; 2024:chap 6.

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Review Date: 9/18/2023  

Reviewed By: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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