Angelman Syndrome

What is Angelman Syndrome?

Angelman Syndrome is a rare genetic condition first identified in 1965 by a British doctor, Harry Angelman, from whom it also gained its name.

Dr Angelman had noticed similarities between a small number of previously undiagnosed children that seemed to indicate they had a common problem. After seeing a painting in the Castelvecchio museum in Verona, Italy entitled A Boy with a Puppet he was inspired to write a medical paper titled Puppet Children.

The syndrome – originally called ‘Happy Puppet Syndrome’ because of the characteristic happy demeanour and stiff jerky movements of the children – was renamed Angelman Syndrome in 1982. Although at first little was known and indeed few other cases identified, in recent years much more has been learned. During the 1980’s advances in genetic medicine made it possible to diagnose increasing numbers of cases and also to start identifying the cause.

In simple terms, it is a chromosome disorder that causes severe learning difficulties. It is now known that irregularities in Chromosome 15 are responsible for AS. However it is also known that there are several different irregularities that can occur in Chromosome 15, all of which result in a diagnosis of AS.

Angelman Syndrome is not a disease, it is a neurological disorder that causes severe learning difficulties, and although those affected have a normal life expectancy, they will require looking after throughout their lives. It’s possible to go from knowing nothing about AS, to being overwhelmed by the information now available to families of those newly diagnosed with AS. It can be very difficult to understand all there is to know about AS very quickly, you’ll probably have lots of questions on a topic you may never have heard of before.


Assert is very proud to be supporting the UK’s only specialist Angelman Syndrome clinics. In conjunction with the NHS, we are holding 3 or 4 clinics each year for both adults and children with AS in Manchester.

The clinics are being held for those who have a clinical need to meet with the professionals. We see 3 or 4 families at each clinic, with each family having an hour for a full consultation with a Clinical Geneticist, Jill Clayton-Smith; a Paediatrician, Dr Dan Hindley; and a Psychologist, Eric Taylor. A Physiotherapist will also be available and we are hoping to have a Speech Therapist, Dietician and other professionals present on the day. A representative from ASSERT will also be attending for the day to discuss ways in which we can support families.

Every patient must be referred by their GP or other doctor sending a written referral to: Dr Jill Clayton-Smith, Genetic Medicine, 6th Floor St Mary’s Hospital, Oxford Rd, Manchester M13 9WL.

Watch our introductory video here:

Diagnosis of Angelman Syndrome

Most AS children are diagnosed between the ages of 3 & 7 when the characteristic physical and behavioural features become evident. The characteristics used for diagnostic criteria are listed below:

Consistent (in 100% of cases)

  • Developmental delay, functionally severe
  • Speech impairment, no or minimal use of words, receptive and non-verbal communication skills higher than verbal ones
  • Movement or balance disorder, usually ataxia of gait and/or tremulous movement of limbs
  • Behavioural uniqueness: any combination of frequent laughter/smiling; apparent happy demeanour; easily excitable personality, often with hand flapping movements; hypermotoric behaviour; short attention span

Frequent (more than 80%)

  • Delayed, disproportionate growth in head circumference, usually resulting in microcephaly (absolute or relative) by age 2
  • Seizures, onset usually <3 years of age
  • Abnormal EEG, characteristic pattern with large amplitude slow-spike waves (usually 2-3/s) facilitated by eye closure

Associated (20-80%)

  • Flat occiput (bone at the back of the skull)
  • Occipital groove
  • Protruding tongue
  • Tongue thrusting; suck/swallowing disorders
  • Feeding problems during infancy
  • Prognathia (protruding lower jaw)
  • Wide mouth, wide-spaced teeth
  • Frequent drooling
  • Excessive chewing/mouthing behaviours
  • Strabismus
  • Hypopigmented skin, light hair and eye colour (compared to family), seen only in deletion cases
  • Hyperactive lower limb deep tendon reflexes
  • Uplifted, flexed arm position especially during ambulation
  • Increased sensitivity to heat
  • Sleep disturbance
  • Attraction to/fascination with water
Dr Harry Angelman
A Boy with a Puppet
by Giovanni Francesco Caroto