Angelman syndrome is a multisystem neurodevelopmental disorder with predominant central nervous system, behavioural, and musculoskeletal involvement. Developmental delay is typically first noted at around six months of age, while the characteristic clinical features manifest after the first year of life. Early symptoms include inconsistent visual fixation, poor grasping, and muscle hypotonia. As the disorder progresses, patients typically develop gait ataxia, increased drooling, and hand stereotypies. Many children also develop epilepsy, often accompanied by characteristic EEG abnormalities. Common dysmorphic features include microcephaly, midface hypoplasia, mandibular prognathism, and a wide mouth. Most patients acquire only a few spoken words, although receptive language is relatively better preserved, and communication is often more effective through gestures or sign language. A hallmark of Angelman syndrome is a happy and friendly disposition, with many patients exhibiting frequent episodes of laughter, sometimes inappropriate to the situation, such as in response to pain. Independent living is not achievable, although life expectancy appears to be nearly normal.
