Does epilepsy contribute to the clinical phenotype of C9orf72 mutation in fronto-temporal dementia?

C9orf72 mutation is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) worldwide. Recently, several reports of patients with FTD who carried the C9orf72 mutation and also manifested epilepsy have been published, since seizures occur in FTD at a higher rate than in the general population, the possible association between epilepsy and C9orf72 mutation remains to be clarified. In the attempt to understand whether epilepsy contributes to the phenotype of the C9orf72 mutation, we compared epilepsy occurrence in patients with FTD who carried the C9orf72 mutation and those who did not. In our sample of 84 patients with FTD, 7.1% of cases reported epilepsy, with no significant differences between subsamples of patients with FTD stratified according to the presence of the C9orf72 mutation or to family history of FTD/parkinsonism/motor neuron disease. Our findings did not support to the possibility that epilepsy represents a characteristic feature of the C9orf72 mutation, as suggested by recent case reports published in the English literature.