The epilepsy phenotype in adult patients with intellectual disability and pathogenic copy number variants

Purpose To characterize the electroclinical features of epilepsy associated with intellectual disability and pathogenic copy number variations (CNVs) Methods we prospectively investigated 61 adult patients with epilepsy and intellectual disability or other neurodevelopmental disorders. We performed high resolution SNP-Array analysis in order to detect clinical relevant chromosomal microdeletions and microduplications. An ordinal logistic regression model was fitted with 34 demographic, clinical and EEG-related variables in order to identify the epilepsy phenotype of patients with pathogenic CNVs. Results chromosome microarray analysis identify non-polymorphic CNVs in 33 patients analyzed: 11 had an established pathogenic microdeletion/microduplication, 22 were carriers of CNVs of unknown clinical significance. Univariate analysis revealed a significant association between pathogenic CNVs and 3 electroclinical variables considered, specifically atypical absence seizures (p < 0.05), tonic seizures (p < 0.05), epileptic spasms (p < 0.01). Conclusions high resolution SNP-Array analysis should be evaluated in adult patients with intellectual disability and epilepsy with peculiar electroclinical features, specifically atypical absence seizures, tonic seizures, and epileptic spasms, resembling a Lennox-Gastaut syndrome without a clear structural lesion.