Early Normal EEG and Seizure-Free Long-Term Follow-Up in Deletion-Positive Angelman Syndrome: A Case Series

A bstract Angelman syndrome (AS) is a rare neurogenetic disorder characterized by global developmental delay, absent or severely impaired speech, movement abnormalities, and distinct behavioral features. The most common genetic mechanism involves maternal deletion of the 15q11–q13 region. We report the case of three pediatric female patients presenting with developmental delay and hypotonia. Electroencephalography demonstrated organized background activity without epileptiform discharges in all patients. Cranial magnetic resonance imaging revealed thinning of the corpus callosum in one patient, while the remaining two showed normal neuroimaging findings. None of the patients had a history of seizures at the time of evaluation. These cases highlight the phenotypic variability of deletion-positive AS and demonstrate that early electroencephalographic findings may be normal, with absence of seizures even during long-term follow-up. Early genetic diagnosis remains essential for accurate management and surveillance. These findings challenge the assumption that deletion-positive AS uniformly presents with early epileptiform abnormalities and highlight the importance of genetic testing even in the presence of normal early electroencephalographic findings.