Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are the most studied genomic-imprinting disorders mapped to chromosome 15q11-q13. Lack of a functional maternal copy of UBE3A, a gene within 15q11-q13, causes AS. PWS and AS have characteristic neurologic, developmental, and behavioral phenotypes plus other structural and functional abnormalities. However, the cognitive and neurologic impairment is more severe in AS, including seizures and ataxia.
