Summary Autosomal dominant mutations in the sodium-gated potassium channel subunit gene KCNT1 have been associated with two distinct seizure syndromes, nocturnal frontal lobe epilepsy (NFLE) and malignant migrating focal seizures of infancy (MMFSI). To further explore the phenotypic spectrum associated with KCNT1, we examined individuals affected with focal epilepsy or an epileptic encephalopathy for mutations in the gene. We identified KCNT1 mutations in 12 previously unreported patients with focal epilepsy, multifocal epilepsy, cardiac arrhythmia, and in a family with sudden unexpected death in epilepsy (SUDEP), in addition to patients with NFLE and MMFSI. In contrast to the 100% penetrance so far reported for KCNT1 mutations, we observed incomplete penetrance. It is notable that we report that the one KCNT1 mutation, p.Arg398Gln, can lead to either of the two distinct phenotypes, ADNFLE or MMFSI, even within the same family. This indicates that genotype–phenotype relationships for KCNT1 mutations are not straightforward. We demonstrate that KCNT1 mutations are highly pleiotropic and are associated with phenotypes other than ADNFLE and MMFSI. KCNT1 mutations are now associated with Ohtahara syndrome, MMFSI, and nocturnal focal epilepsy. They may also be associated with multifocal epilepsy and cardiac disturbances.

AED Antiepileptic drug VNS Vagus nerve stimulationAIM The aim of this study was to evaluate the effects of vagus nerve stimulation (VNS) in children with intractable epilepsy on seizure frequency and severity and in terms of tolerability and safety.METHOD In this study, the first randomized active controlled trial of its kind in children, 41 children (23 males; 18 females; mean age at implantation 11y 2mo, SD 4y 2mo, range 3y 10mo-17y 8mo) were included. Thirty-five participants had localization-related epilepsy (25 symptomatic; 10 cryptogenic), while six participants had generalized epilepsy (four symptomatic; two idiopathic). During a baseline period of 12 weeks, seizure frequency and severity were recorded using seizure diaries and the adapted Chalfont Seizure Severity Scale (NHS3), after which the participants entered a blinded active controlled phase of 20 weeks. During this phase, half of the participants received high-output VNS (maximally 1.75mA) and the other half received low-output stimulation (0.25mA). Finally, all participants received high-output stimulation for 19 weeks. For both phases, seizure frequency and severity were assessed as during the baseline period. Overall satisfaction and adverse events were assessed by semi-structured interviews.RESULTS At the end of the randomized controlled blinded phase, seizure frequency reduction of 50% or more occurred in 16% of the high-output stimulation group and in 21% of the low-output stimulation group (p=1.00). There was no significant difference in the decrease in seizure severity between participants in the stimulation groups. Overall, VNS reduced seizure frequency by 50% or more in 26% of participants at the end of the add-on phase The overall seizure severity also improved (p<0.001).INTERPRETATION VNS is a safe and well-tolerated adjunctive treatment of epilepsy in children.Our results suggest that the effect of VNS on seizure frequency in children is limited. However, the possible reduction in seizure severity and improvement in well-being makes this treatment worth considering in individual children with intractable epilepsy.Vagus nerve stimulation (VNS) is a neuromodulatory treatment that is used as an adjunctive therapy for individuals with medically refractory epilepsy who are not eligible for epilepsy surgery or in whom surgery has failed, and in whom non-epileptic events are excluded. VNS consists of chronic intermittent electrical stimulation of the vagus nerve, delivered by a programmable pulse generator (neurocybernetic prosthesis [NCP]; Cyberonics Inc, Webster, TX, USA).Randomized active controlled trials, which have predominantly included adults, have demonstrated the safety and efficacy of VNS: 1,2 seizure frequency decreased by more than 50% in 23 to 31% of individuals in the treatment groups compared with 13 to 15% in the placebo group. These trials led to the U.S. Food and Drug Administration approval in 1997 of the use of VNS as adjunctive therapy in individuals older than 12 years with partial epilepsy refractory to treatment with...

In the list of consortium members for the Epilepsy Phenome/Genome Project, member Dina Amrom's name was misspelled as Amron. The authors regret the error.

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