Familial hemiplegic migraine due to L263V SCN1A mutation: Discordance for epilepsy between two kindreds from Douro Valley

BackgroundSCN1A is the most relevant gene in epilepsy. Only seven SCN1A mutations have been identified in 10 familial hemiplegic migraine (FHM) kindreds worldwide.Cases and kindredsIn 2009, we presented a kindred with FHM due to the L263V SCN1A mutation. In the current study, we report a novel FHM3 kindred from the same village. The first family exhibited the co-occurrence of FHM and epilepsy. No case of epilepsy was observed in the new kindred. An L263V mutation was found in all patients, and the haplotype analysis supports a unique mutational event.CommentsDespite its bioelectric activity, the SCN1A L263V mutation most likely requires a combination of several endogenous or environmental induction stimuli to attain an epileptogenic threshold.