Angelman syndrome is a neurodevelopmental disorder which was first described in 1965. The main signs and symptoms of Angelman syndrome are learning disability, jerky movements, a tendency to seizures and a happy, sociable personality. Children with Angelman syndrome usually present with delay in reaching their developmental milestones and often do not learn to sit until around one year of age. The majority of children will learn to walk but tend to have a characteristic wide-based, stiff-legged gait. General health is usually good but seizures can be a problem, particularly in childhood. Individuals with Angelman syndrome almost always have characteristic abnormalities on EEG (Electroencephalogram) testing. Many, but not all children with Angelman syndrome have a typical facial appearance with a wide, smiling mouth, deep set eyes and prominent chin. These features become more prominent as children get older. Some Angleman individuals, especially those who have chromosome 15 deletion may be fairer in complexions than the rest of their family. Adults with Angelman syndrome are much less hyperactive than younger children and have a better concentration span. They remain dependent on others, but can acquire a variety of skills to help with daily living. Medical complications in older patients include the development of joint contractures, curvature of the spine and oesophageal reflux. Seizures may also return in adulthood.

Inheritance patterns
Angelman syndrome may arise from a variety of genetic abnormalities, all of which involve the same part of chromosome 15 which contains the gene called UBE3A. The majority of children have a small deletion of the 15q11-13 region. Diagnostic testing for Angelman syndrome is complex. In the majority of families only one child is affected by Angelman syndrome but in 5-10% of cases brothers, sisters and extended family members may be affected. It is recommended that parents of an affected child should approach their local clinical genetics centre for genetic counselling and testing on an individual basis.

Prenatal diagnosis
Prenatal tests are available in those families where a definite genetic abnormality has been identified.

Medical text written November 1991 by Contact a Family. Approved November 1991 by Professor M Patton, Professor of Medical Genetics, St Georges Hospital Medical School, London, UK and Dr J E Wraith, Consultant Paediatrician, Royal Manchester Children's Hospital, Manchester, UK. Last updated August 2002 by Jill Clayton-Smith, Consultant Clinical Geneticist, St Mary's Hospital, Manchester, UK.

The information below has been updated September 2007 by Dr O Udwin, Consultant Clinical Child Psychologist, West London Mental Health NHS Trust, London UK and Dr A Kuczynski, Child Clinical Psychologist, South London & Maudsley NHS Trust, London, UK.

Psychological and behavioural characteristics

All individuals with Angelman syndrome have severe or profound learning disabilities. Furthermore, they have marked difficulties in their speech and language development. Early prelinguistic babbling and vocal play is often absent. Children typically acquire no more than a few words, and approximately one-third do not talk at all. Their understanding of language may be meaningfully better than their speech, and most use some nonverbal means of communication, including gestures, signs and picture boards.

Hyperactivity and "overexcitability" is common in childhood. Many affected children find it difficult to concentrate during the day and to settle and stay asleep at night. Bedtime may provoke tantrums. The overactivity and sleep problems may decrease with age.

Children and adults are typically described as happy, sociable, and affectionate, and as enjoying physical contact. They display frequent bouts of giggling laughter and hand-clapping or flapping. Although these are often a response to what is going on around them, the humour may at times be inappropriate. Still, individuals with Angelman syndrome may be less prone to irritability and social withdrawal than others with comparable general developmental difficulties. Many of them love music and water, and are fascinated by mirrors and other reflective surfaces.

Many children with Angelman syndrome are able to learn important self-care skills, including feeding and toileting, and as they grow older they may undertake other domestic tasks, such as dusting and setting the table with assistance. However, they all require supervision in their daily lives.

Further Online Resources
Medical texts in The Contact a Family Directory are designed to give a short, clear description of specific conditions and rare disorders. More extensive information on this condition can be found on a range of reliable, validated web sites and links to them are included in the CD-ROM version of this Directory. Further information on these resources can be found in our Medical Information on the Internet article.

ASSERT
PO Box 13694
Musselburgh
EH21 6XZ
Tel/Fax: 01268 415940
e-mail: assert@angelmanuk.org
Web Site http://www.angelmanuk.org

ASSERT is a National Registered Charity No. 1021882, established in 1992. It offers support to families by telephone, e-mail and letter. Activities include: fundraising for research and group activities; participation in research studies; and raising awareness of the condition. It publishes a regular Newsletter and has information available, details on request. ASSERT holds a biennial conference and is in touch with over 450 families.

Group details last confirmed October 2007.