Angelman syndrome
a congenital disorder caused by a genetic abnormality on chromosome 15 and characterized by abnormalities or impairments in neurological, motor, and cognitive functioning, including severe learning disabilities, absence of speech, and a stiff, jerky gait and movements (see ataxia). Individuals with Angelman syndrome have happy dispositions and a propensity for paroxysms of inappropriate laughter. Craniofacial abnormalities, including a small or unusually flattened head, a large mouth, and a protruding jaw, are also common. The condition was formerly called happy-puppet syndrome. [Harry Angelman (1915–1996), British pediatrician]