Detection of microchromosomal aberrations in refractory epilepsy: a pilot study

Seizures often occur in patients with microchromosomal aberrations responsible for moderate to severe intellectual disability. We hypothesised that epilepsy alone could be caused by microdeletions or microduplications, which might also relate to epilepsy refractory to medication. Chromosomes from 20 subjects with epilepsy and repeated failure of antiepileptic medication were examined using molecular methods. Firstly, the 41 subtelomeric regions were scanned using fluorescence in situ hybridization and multiplex ligation-dependent probe amplification. Secondly, a genome-wide scan was carried out using oligonucleotide-array comparative genome hybridisation on two platforms: Nimblegen and Agilent. Two aberrations (2/20) were identified: a recurrent microdeletion at 15q13.3 previously characterised in patients with seizures that generally respond to medication, and a novel 1.15 Mb microchromosomal duplication at 10q21.2 also present in the unaffected mother. We conclude that gene content of microchromosomal aberrations is not a major cause of refractory seizures, but that microchromosomal anomalies are found in an appreciable fraction of such cases.