Angelman syndrome in three siblings: characteristic epileptic seizures and EEG abnormalities.

Neurologic findings in 3 siblings with Angelman syndrome (AS) with apparently normal karyotype but DNA deletion of 15q11-q12 deriving from their mother are described. Increased auditory brainstem response (ABR) thresholds were noted in all 3. Interictal EEG findings included periodic 2- to 3-Hz high-voltage slow wave bursts bioccipitally and sporadic slow spike wave complexes mainly bifrontally. EEG findings suggestive of minor epileptic status were apparent in the elder brother and may be a characteristic feature in young AS patients. Seizures suggestive of generalized epilepsy have been reported in 90% of AS patients. AS is considered a good model of symptomatic generalized epilepsy associated with chromosomal DNA deletion of the (GABA)A receptor beta 3-subunit gene.