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.
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 UBE3A passed on from the mother doesn't work the way it should. In some cases, AS is caused when two copies of 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.
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
- 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
- DNA test to see if copies of the gene from both parents are in an inactive or active state
- Gene mutation in the mother's copy of the gene
Other tests may include:
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
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 group home.
Complications may include:
- Severe seizures
- Gastroesophageal reflux (heartburn)
- Scoliosis (curved spine)
- Accidental injury due to uncontrolled movements
When to Contact a Medical Professional
Call your health care provider if your child has symptoms of this condition.
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.
Dagli AI, Mueller J, Williams CA. Angelman syndrome. GeneReviews. Seattle, WA: University of Washington; 2015:5. PMID: 20301323 www.ncbi.nlm.nih.gov/pubmed/20301323. Accessed August 1, 2017.
Nussbaum RL, McInnes RR, Willard HF. The chromosomal and genomic basis of disease: disorders of the autosomes and sex chromosomes. In: Nussbaum RL, McInnes RR, Willard HF, eds. Thompson & Thompson Genetics in Medicine. 8th ed. Philadelphia, PA: Elsevier; 2016:chap 6.