- ANGELMAN SYNDROME Angelman Syndrome is a neurological disorder associated with developmental delay and with characteristic facial appearance and behaviour. Psychomotor delay and low muscle tone are usually observable in infancy. Affected children have abnormal electro-encephalograms (EEG) - a technique used to record the pattern of brain waves. The majority of affected children have seizures and ...www.cafamily.org.uk/Direct/a54.html