Nineteen patients with RE (ie, those from tables 1 and 2 that do not carry hotspot CNVs described earlier, apart from one patient that had both a hotspot and rare CNV) were found to either carry a rare CNV that disrupted genes that are recurrent risk factors for epilepsy (n=5, disrupting GRIN2A, KCTD7, ARHGEF15, CACNA2D1 and ARHGEF4) (table 1), genes that are associated with other neurological conditions or that are involved in neuronal signalling and/or development (table 2). Here, ARHGEF4 is linked to epilepsy.