A Rett Patient with a Typical Angelman EEG


Address correspondence and reprint requests to Dr. L.A.E.M. Laan at Department of Neurology and Clinical Neurophysiology, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. E-mail: L.A.E.M.Laan.neurology@lumc.nl


Summary:  Purpose: To draw attention to the phenomenon that EEG characteristics of both Angelman syndrome (AS) and Rett syndrome (RS) can be found in the same patient, as evidenced by the description of one case. There are specific EEG patterns in AS patients, in which the most frequently occurring EEG characteristics are rhythmic triphasic 2- to 3-Hz, high-voltage (200–500 μV) activity, mixed with spikes or sharp waves, with a maximum over the frontal regions. EEG changes in RS patients are less specific and can show multifocal, mostly central or centrotemporal epileptiform discharges in combination with slow background activity.

Methods: A 6-year-old girl with RS and a proven MECP2 mutation was described.

Results: She had an EEG pattern at age 2 years comparable with the clinical diagnosis of RS, and an EEG at age 6 years comparable with an AS EEG.

Conclusions: We wish to draw attention to this phenomenon, although there is as yet no evident explanation for it. We advise MECP2 examination in AS patients of unknown genetic etiology whose EEG examinations are/were pathognomonic for AS to exclude RS.