Abstracts

Angelman syndrome (AS) is determined by different genetic mechanisms, affecting the maternal chromosome 15. One of these, paternal UPD, occurs in 1-3% of all AS patients, with strong evidence of a milder phenotype, constituting a putative subgroup that represents a challenge for clinical diagnosis. To date, electroclinical data in UPD is scarce and remains unknown whether the binomial epilepsy-EEG is similar to that reported in patients with DEL. We describe the electroclinical phenotype of four children with UPD and compare these findings to DEL patients. We included 24 patients with DEL and 4, with UPD. We characterized epilepsy by history obtained with a pre-standard questionnaire, corroborated by medical records, personal contact with previous physicians, and video-EEG monitoring (mean 8 hours) in 21 patients. A total of 91 EEGs (mean 2.6 EEG/patient), ranging from 4 months to 22 years (mean 5y3mo), were analyzed. Suggestive EEG patterns for AS were classified according to Boyd et al. [1988] and were denominated: delta pattern (DP), theta pattern (TP) and posterior discharges (PD). We compared prevalence and severity of epilepsy plus the EEG features mentioned above between our UPD and DEL patients. For the purpose of [underline]statistical analysis[/underline], we added data of published UPD to our own patients and compared them with our DEL patients, using Fisher, Student t, x² and Mann-Whitney[rsquo]s tests with level of confidence of [alpha]=0.05. Our data showed that none UPD had refractory epilepsy compared to 19 DEL patients. Only one DEL patient (4.8%) had a normal age-related background, whereas three (75%) non-DEL had this feature. Suggestive EEG occurred in both groups. Our UPD patients presented infrequent and short runs of DP and PD, while DEL had prolonged and quasi-continuous/continuous patterns, as well as electrographic seizures and unspecific interictal epileptiform discharges. Analyzing our patients plus previous work, we observed that prevalence of epilepsy was significantly higher in patients with DEL (p[lt]0.001) than in those with UPD. Parameters indicating severity of epilepsy (earlier age of onset, higher occurrence of disabling or multiple seizures, SE, and refractoriness) were also significantly higher in patients with DEL. In relation to EEG, the presence of an abnormal background and the higher frequency of posterior discharges in DEL were the only significant differences between groups. The analysis of our and published patients showed that in UPD, when epilepsy occurred, it was milder compared to patients with deletion, although a suggestive EEG was observed in most patients. Although, UPD patients do not completely fit the scenario delineated for AS, suggestive EEG patterns were as helpful as in other groups to corroborate the diagnosis. (Supported by CNPQ and FAPESP)