Angelman syndrome (AS) is a genetic disorder rather than an epilepsy syndrome. AS is a rare condition, which affects about one in 15,000 children. It used to be called the ‘happy puppet’ syndrome because children with this syndrome often have a happy mood and movements that can look like a puppet. However, Angelman syndrome should be the only name used today. Children have learning difficulties and speech delay that are usually severe. They also have jerking movements, tongue-thrusting, a characteristic (typical) facial appearance, and a happy mood with sudden bursts of laughter and epilepsy. Many children also have a fascination for water, usually running water. The condition is due to an abnormality in a gene which is on chromosome 15. It is usually diagnosed between 4 and 10 years of age, but sometimes earlier.
Children with AS may show delay in development skills (milestones) in the first one or two years of life. However, the diagnosis may not be made until the age of 3 years when the behavioural features (cheerful mood and bursts of sudden and unexplained laughter) become more obvious. The facial appearance also becomes more noticeable in the second and third year of life, with the development of a pointed chin, thin wide mouth and protruding tongue. Many children will show a slow rate of brain and therefore head growth and will develop microcephaly (a small head).
Epilepsy usually starts between 18 months and two years of age and may initially happen with high temperatures which may lead to a diagnosis of 'febrile convulsions'. However, most of the seizures happen without a fever. Eventually seizures will happen in 8 or 9 out of every 10 children who have AS. The types of seizures include myoclonic (‘jerks’), atonic or astatic (‘drops’) prolonged blank episodes ('atypical absences') and tonic (‘stiffening’) seizures. Generalised tonic-clonic seizures and focal onset (partial) seizures are less common. Children may also have very prolonged periods during which they are very quiet, unresponsive, may drool excessively and are unable to eat. This is called ‘non-convulsive status epilepticus’ (NCSE). An EEG is often needed to confirm the child is in NCSE. Non-convulsive status epilepticus may last many minutes to hours or even days. It may happen repeatedly over many days or weeks. NCSE is not the same sort of medical emergency as convulsive status epilepticus but still needs to be treated.
Children with AS do usually learn to walk, but this is late (between the ages of 2 and 5 years, sometimes later). Their walking is fast and unsteady, called ‘ataxic’. Their movements are also very shaky and jerky. Speech delay is very common and is usually quite severe. They have problems understanding what is said to them (called ‘receptive dysphasia’) and also in expressing their thoughts (this is called ‘expressive dysphasia’). Some children only have 2 or 3 words of speech at most. They therefore have to communicate by facial expression or, rarely, by signs or gestures. A number of them will also show signs of autism. They have very short attention spans. Most children are never able to be toilet trained and will have to attend a special school.
The diagnosis of AS is usually made on the basis of the facial appearance, behaviour and epileptic seizure types of the children. The EEG may also be useful in helping to confirm the condition. Brain scans are not helpful in diagnosing Angelman syndrome, because they are usually normal. If the child is found to have the abnormality on chromosome 15, then this confirms the diagnosis of AS. This abnormality is found in just over two-thirds of children with AS. The chromosome abnormality can be looked for in a blood test or, if the blood test is normal, by taking a very small sample of skin (called a skin biopsy).
In most children with AS, the epilepsy can be controlled with epilepsy medicines. Medicines that are commonly prescribed include sodium valproate (Epilim), clonazepam (Rivotril), lamotrigine (Lamictal) and levetiracetam (Keppra). Another medicine called piracetam (Nootropil) may also be effective in controlling the jerky movements. Carbamazepine (Tegretol) may also be helpful, although usually less so than the medicines listed above. The ketogenic diet and vagus nerve stimulation (VNS) may also be effective in a number of children with AS. Children also need intensive help with communication. This is given by speech and language therapists. They are usually also seen by a physiotherapist and occupational therapist. Many children have poor sleep patterns and either find it difficult to fall asleep or wake frequently throughout the night. There is a medicine called melatonin that may help improve sleep.
Families who have a child with AS should have the opportunity to see a specialist in genetics (called a ‘clinical geneticist’) as well as a specialist in epilepsy. A specialist in genetics will be able to discuss the genetic diagnosis and look at the risk of AS occurring in other children in the family.
There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.
Information about treatments for children can be found on the Medicines for Children website.
If your child has this syndrome they may have prolonged or repeated seizures. Your child’s doctor will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.
The general health of children with AS is good and there are no major life-threatening events. The epileptic seizures are frequent and may be difficult to treat with epilepsy medicines for the first few years. The epilepsy usually improves with time, usually after the age of 12 years. In fact, in a number of children, the epileptic seizures disappear completely after the age of 12 or 14 years. Many children with AS also develop behaviour problems in mid to late childhood and these may be very difficult to manage.
What is a syndrome?
A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether the child has physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.
If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact the Epilepsy Action Helpline.
Epilepsy Action would like to thank Dr Richard Appleton, consultant paediatric neurologist and honorary professor in paediatric neurology at Alder Hey Children’s Hospital, Liverpool, UK for preparing this information.