Angelman syndrome


Angelman syndrome is a genetic disorder that affects the nervous system and causes severe physical and intellectual disability.

A person with Angelman syndrome will have a near-normal life expectancy, but needs looking after for the rest of their life.

Characteristics of Angelman syndrome

A child with Angelman syndrome will begin to show signs of delayed development at around 6 to 12 months of age, such as being unable to sit unsupported or make babbling noises.

Later, they may not speak at all or may only be able to say a few words.  However, most children with Angelman syndrome will be able to communicate using gestures, signs or other symptoms.

The movement of a child with Angelman syndrome will also be affected. They may have difficulty walking because of problems with balance and co-ordination (ataxia). Their arms may tremble or move jerkily, and their legs may be stiffer than normal.

A number of distinctive behaviours are associated with Angelman syndrome. These include:

  • frequent laughter and smiling, often with little stimulus
  • being easily excitable, often flapping the hands
  • being restless (hyperactive)
  • having a short attention span
  • problems sleeping and needing less sleep than other children
  • a particular fascination with water

By around two years of age, an abnormally small head which is flat at the back (microbrachycephaly) will be noticeable in some children with Angelman syndrome. Children with Angelman syndrome may also start to have seizures (fits) around this age.

Other possible features of the syndrome include:

  • tendency to stick the tongue out
  • crossed eyes (strabismus)
  • pale skin, and light-coloured hair and eyes in some children
  • a wide mouth with widely spaced teeth
  • a side-to-side curvature of the spine (scoliosis)
  • walking with arms in the air

Some young babies with Angelman syndrome may have problems feeding because they're unable to co-ordinate sucking and swallowing. In such cases, a high-calorie formula may be recommended to help the baby gain weight. Babies with Angelman syndrome may need to be treated for reflux.

Causes of Angelman syndrome

In most cases of Angelman syndrome, the child's parents don't have the condition and the genetic difference responsible for the syndrome occurs by chance around the time of conception.

Angelman syndrome usually happens when the gene known as UBE3A is either missing or not working properly. A gene is a single unit of genetic material (DNA) that acts as an instruction for the way an individual is made and develops.

Most cases of Angelman syndrome are caused by the child not getting a copy of the UBE3A gene from its mother, or the gene not working. This means there's no active copy of the gene in the child's brain.

In a small number of cases, Angelman syndrome happens when a child gets 2 copies of the gene from their father, rather than 1 from each parent.

Sometimes the cause of Angelman syndrome is unknown. Most children in these unexplained cases have different conditions involving other genes or chromosomes.

Diagnosing Angelman syndrome

Angelman syndrome may be suspected if a child's development is delayed and they have the syndrome's distinctive characteristics (see above).

A blood sample can be taken to confirm the diagnosis. A number of genetic tests will be carried out on the sample. These may include:

  • any chromosomes or pieces of chromosomes that are missing
  • changes in the mother's or father's UBE3A gene that they may have passed on
  • changes in the child's UBE3A gene that would stop it from working

For each child with Angelman syndrome, it's important to know the genetic change that caused the condition. This helps to determine whether there's a risk of it occurring again in another child, or whether there are implications for other members of the family.

Most children with Angelman syndrome are diagnosed between the ages of 18 months and 6 years, when the typical physical and behavioural symptoms become apparent.

If your child is diagnosed with Angelman syndrome, you should be given the opportunity to discuss the genetic diagnosis and implications with a genetic doctor.

Managing Angelman syndrome

Some of the symptoms of Angelman syndrome can be difficult to manage, and you're likely to need help from a wide range of different healthcare professionals.

Your child may benefit from some of the following treatments and aids:

  • anti-epileptic medicine to control seizures
  • physiotherapy may improve posture, balance and walking ability; it's also important to prevent permanent stiffening of the joints as people with Angelman syndrome get older
  • communication therapy may help them develop non-verbal language skills, such as sign language and using visual aids; using iPad applications and similar tablet devices may also help
  • behavioural therapy may be recommended to help overcome behaviours you find hard to manage, such as hyperactivity and a short attention span

In later childhood, the seizures usually improve, although they may return in adulthood. With age, people with Angelman syndrome become less hyperactive and may sleep better.

Most people with the syndrome will have learning disability and limited speech throughout their life. In adults, some mobility may be lost and joints may stiffen.

People with Angelman syndrome usually have good general health and are often able to improve their communication and acquire new skills.

While there's currently no cure for Angelman syndrome, research into treatments is being done in other countries. There are also clinical trials looking at treatment for some of the symptoms associated with Angelman syndrome, such as seizures.

Help and support

AngelmanUK is a charity providing information and support for parents and carers of people with the syndrome.

As well as visiting the website, you can also call the charity's helpline on 0300 999 0102 to speak with parents of people with Angelman syndrome, who can offer you help and advice.

Information about your child

If your child has Angelman syndrome, your clinical team will pass information about them on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.

Find out more about the register.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 17/11/2021 13:05:58