Angelman syndrome (AS) is known as an intellectual disability related to speech impairment, ataxia and behavioral uniqueness, including a combination of frequent laughter and smiling, apparent happy demeanor, excitable personality and hypermotor behavior. In this report, we present a 5-year-old girl with AS associated with atypical clinical manifestations, including developmental dysplasia of the hip and simian line in the right hand, and her elder sister with AS. Even if any gene mutation cannot be demonstrated, it should be kept in mind that different mutations may exist in the cases that are the suggestive of clinical AS. Therefore, AS patients can be exposed to special education, and their quality of life can be elevated.
Keywords: Angelman syndrome; behavioral–emotional disorder; children; seizure.