Abstracts

Rationale: Chromosome 15q duplications have been increasingly found in patients with epilepsy. Previous publications have correlated seizures in patients with isodicentric duplications, including single case reports of Lennox-Gastaut syndrome in patients with chromosome 15q duplications. The single case reports have not specifically addressed seizure age of onset, EEG findings, or response to therapy in children with chromosome 15q duplications. Methods: Medical histories from three pediatric patients from Mayo Clinic Rochester with epilepsy and chromosome 15q duplications were reviewed for seizure classification, EEG patterns, and responses to therapy.Results: Three children, age 21 months to 15 years, with chromosome 15q duplication were reviewed. All three patients have medically refractory epilepsy, with EEG findings of multifocal spike and sharp waves, as well as generalized and focal onset seizures. Two patients have isodicentric duplications, and presented with seizure onset in infancy and developmental delay. These patients are treated with felbamate and the ketogenic diet with significant improvement, although not resolution, of seizures. One also underwent corpus callosotomy with significant improvement of tonic seizures. One patient has an interstitial duplication, and at age 12 developed epilepsy and developmental regression. He had good response to the ketogenic diet, but is on a modified Atkins diet due to familial compliance, in addition to divalproex and topiramate.Conclusions: Epilepsy has previously been reported in patients with isodicentric chromosome 15q duplication. There has not previously been a report of interstitial duplications causing epilepsy, or a description of the anti-epileptic medications found to be most helpful. All three of our patients had intractable generalized and focal onset seizures, and significant improvement in seizure control with the ketogenic diet, suggesting the ketogenic diet may be a preferred treatment option for these children. Furthermore, although this is a small case series, it is possible that the type of duplication, isodicentric or intersitial, may affect the epilepsy syndrome phenotype. Our patients with isodicentric duplications were both infants at presentation, and our patient with interstitial duplication presented in adolescence. Further study is needed to determine if the genotype-phenotype correlations seen in this children are consistent across a broader population.