Angelman syndrome

Overview

Angelman syndrome is a rare genetic condition that affects the nervous system. It happens when the maternal UBE3A gene does not work as expected. This change leads to delayed development, trouble with speech, challenges with balance and movement, and intellectual disability. Seizures also are common.

Many children with Angelman syndrome smile or laugh often and appear easily excited. These behavior traits may be early clues for families and care teams.

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 lifespan. But the condition can't be cured. Treatment focuses on supporting development, building communication skills, and managing medical, sleep and developmental issues.

Symptoms

Early signs of Angelman syndrome can be subtle at first, then become clearer as children grow. Angelman syndrome symptoms can affect development, movement, behavior and overall health. Symptoms may include:

• Seizures, often starting between ages 2 and 3.
• Small head size by age 2.
• Light-colored hair, skin or eyes.
• Tongue thrusting.
• Crossed eyes, called strabismus.
• Curved spine, called scoliosis.

Angelman syndrome symptoms often appear in clusters. These common categories help show how the condition can affect daily life:

Development and communication

• Developmental delays, including no crawling or babbling by 6 to 12 months.
• Intellectual disability.
• No speech or very limited speech.

Movement and balance

• Trouble walking, moving or balancing.
• Stiff or jerky movements.
• Movement patterns such as hand flapping or lifting the arms while walking.

Behavior

• Frequent smiling and laughing.
• Seeming very happy or easily excited.

Feeding and sleep

• Feeding challenges in babies, such as trouble sucking or taking a bottle.
• Trouble going to sleep and staying asleep.
• Frequent waking.

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.

Causes

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.

How a child gets Angelman syndrome

• Think of each gene as an instruction card. For most genes, children get one instruction card from their mother and one from their father. The body usually reads both cards.
• But the UBE3A gene works differently in the brain. In the brain, only the mother's card is readable. The father's card is there, but it stays turned off.
• In Angelman syndrome, the mother's card is missing, damaged or unreadable. So the brain is left without instructions from UBE3A. Without those instructions, parts of brain development — such as movement, learning, speech and coordination — don't happen in the typical way.

All of these lead to the same problem: The brain doesn't receive the working UBE3A instructions it needs.

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.

In rare situations, Angelman syndrome can be passed down from a parent. This happens when the parent carries a specific UBE3A gene change or an imprinting condition. In these families, the chance of having another child with Angelman syndrome may be higher. Not all types of genetic changes can be passed on. Only a few specific ones carry a higher recurrence risk.

Complications

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.
• Seizures. Most affected children experience recurrent seizures. They sometimes can be difficult to manage, requiring ongoing management with medicines.
• Dental problems and vision issues. These may include nearsightedness or crossed eyes.
• 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.

Prevention

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.

Genetic testing can help find the exact gene condition in a person. This is very important for knowing if it might happen again and for helping families plan future pregnancies.