Angelman syndrome due to a novel splicing mutation of the UBE3A gene.

Angelman syndrome is a neurodevelopmental disorder characterized by mental retardation, absence of speech, seizures, abnormal electroencephalography (EEG), and happy disposition. The syndrome results from lack of function of the maternal copy of the UBE3A gene on the imprinted Prader-Willi/Angelman syndrome critical region; it is caused by large deletions, paternal uniparental disomy, imprinting center defects or UBE3A deletions, and point mutations. We found a novel splice-site mutation of the UBE3A gene in a child with clinical and EEG features of Angelman syndrome. This case further points out the fact that individuals with Angelman syndrome and mutations of the UBE3A gene have a phenotype that tends to be rather mild, however, undistinguishable, both from the clinical and the electrophysiological points of view, from the Angelman syndrome phenotype due to other known molecular mechanisms.