Angelman syndrome: symptoms, causes, diagnosis and outlook

Angelman syndrome is a rare neurological disorder. Angelman UK, the UK charity, describes characteristic features as delayed development, severe learning difficulties, little or no speech, and issues with movement and balance. It was first described in 1965 by a British doctor, Harry Angelman, after whom it is named.

People with Angelman syndrome usually have good general health and are often able to improve their communication and acquire new skills, according to the NHS. Most will have a learning disability and limited speech throughout their life.

Not every child has every feature. The NHS describes how the picture usually builds over the first few years, and notes that a child may not have all the characteristic behaviours.

The NHS says it usually happens when the gene known as UBE3A is either missing or not working properly. A child usually gets 2 copies of this gene, one from each parent, but only the copy from the mother is active in the brain. Most cases are caused by the child not getting a copy of UBE3A from its mother, or the gene not working, so there is no active copy in the child’s brain.

In a small number of cases it happens when a child gets 2 inactive copies of the gene from their father, rather than 1 from each parent. Sometimes the cause is unknown. Angelman UK explains that this effect, called imprinting, means that disruption to the active copy causes problems because there is no back-up version.

In most cases the parents do not have the condition and the genetic difference happens by chance around the time of conception, according to the NHS.

The NHS says the condition may be suspected if a child’s development is delayed and they have the syndrome’s distinctive characteristics. A blood test is used to confirm the diagnosis. Several genetic tests are done on the blood sample, looking for missing chromosomes or pieces of chromosomes, changes in the mother’s or father’s UBE3A gene, and changes in the child’s UBE3A gene that would stop it working.

Most children are diagnosed between 9 months and 6 years of age, when physical and behavioural symptoms become apparent. If your child is diagnosed you will be able to talk to a genetic doctor about what support they might need. It is important to know the genetic change responsible, because this helps to determine your chance of having another child with the syndrome.

There is currently no cure, but support and treatment can help. The NHS lists the following approaches. Research into treatments is being done in other countries, and there are clinical trials looking at treatment for some of the symptoms, such as seizures.

• Anti-epileptic medicine to control seizures.

• Physiotherapy to improve posture, balance and walking ability and to prevent permanent stiffening of the joints as people get older.

• Communication therapy to develop non-verbal language skills, such as sign language and visual aids, or ways to help communicate such as Signalong, Makaton or PECS; tablet apps may also help.

• Behavioural therapy to help overcome behaviours that are hard to manage, such as hyperactivity and a short attention span.

• Treatment for reflux and, if needed, feeding support in babies.

The NHS says people with Angelman syndrome have a near-normal life expectancy, but will need support throughout their life. In later childhood the seizures usually improve, although they may return in adulthood. With age, people become less hyperactive and may sleep better. In adults, some mobility may be lost and joints may stiffen.

Angelman UK has pages on the syndrome in adulthood, epilepsy, sleep, scoliosis and challenging behaviour, among other issues. The NHS suggests reading about how to care for a disabled child and about support and benefits for carers.

Feeding difficulties can appear in the first months. The NHS says some young babies are unable to co-ordinate sucking and swallowing, and may need to be fed through a feeding tube, and may need treatment for reflux. Later in childhood Angelman UK lists a love of food and grabbing food among common behaviours.

The sources used here do not give specific dietary advice beyond this, so ask your child’s paediatric team or a dietitian about feeding, reflux and weight.

Angelman UK says that, for most people, the chance of having another baby with the syndrome is the same as anyone else, around 1 in 15,000 to 1 in 20,000. If a child has the form caused by a change in the UBE3A gene itself, the chance of having another child with it is much higher, around 1 in 2.

For this reason it is important to know what type of Angelman syndrome your child has. You should be offered an appointment with a geneticist when your child is diagnosed. If this is not offered and you are considering more children, Angelman UK says to ask your GP for a genetics referral.

On the NHS the route starts with a GP or health visitor raising concerns about development, followed by paediatric assessment and genetic testing, then specialist support such as neurology for seizures, physiotherapy and speech and language therapy. The NHS says your clinical team will pass information about your child to the National Congenital Anomaly and Rare Disease Registration Service, which helps scientists look for better ways to prevent and treat the condition, and that you can opt out at any time.

Private paediatric neurology and genetic testing services exist, but the NHS pathway also provides genetic testing and counselling once the diagnosis is suspected. Angelman UK is the charity providing information and support for parents and carers.