[Epileptic seizures in Angelman syndrome]

Angelman syndrome (AS) is a heterogeneous genetically-based disorder that is characterised by severe mental retardation, absence of language, ataxia, craniofacial dysmorphia and a characteristic behavioural phenotype.

We analyse 12 patients with a mean age of 10.9 years diagnosed with AS. The study focuses on the characteristics of epilepsy and attempts to correlate the findings with the genotype of the disease.

All the patients presented early-onset generalised seizures and all except one had polymorphic seizures. Eight of them also presented focal seizures. All the patients displayed electroencephalographic alterations before the age of two years. Although there are no pathognomonic abnormalities in the electroencephalogram (EEG), knowledge of them in AS can be an important element of assessment for reaching an early diagnosis of this condition. In our series, all the patients with 15q11-13 deletion presented an EEG pattern that was typical of the disease. The most commonly used and most effective antiepileptic drug was valproic acid (used in all patients), followed by lamotrigine and clobazam. Up to 10 antiepileptic drugs had been tried in some patients. Epilepsy usually has a very early onset and even precedes the diagnosis of AS in most cases, which means that the epileptic seizures can be an important aid in reaching an early diagnosis. Suitable classification of such seizures is essential.

AS must be considered as a differential diagnosis in children who present early severe epilepsy together with psychomotor retardation and important gait and language disorders. This diagnosis is backed by the typical findings in the EEG.