SCN1A mutations were found in 12 of the 71 patients (16.9%; ten with DS, and two with seizures in a Generalized Epilepsy with Febrile Seizures+(GEFS+) context).
We analyzed the occurrence of FS and epilepsy among first- and second-degree relatives (N = 867) of 74 SMEI probands with SCN1A mutations (70 de novo, four inherited) and compared data with age-matched and ethnically matched control families.
Rare variants of small effect size in neuronal excitability genes influence clinical outcome in Japanese cases of SCN1A truncation-positive Dravet syndrome.
We used an ultra-sensitive quantification method, micro-droplet digital PCR (mDDPCR), to detect parental mosaicism of the proband's pathogenic mutation in SCN1A, the causal gene of DS in 112 families.
The induction of short repeated seizures, at the age of disease onset for Scn1a mouse models (P21), had no effect in WT mice, but transformed the mild/asymptomatic phenotype of Scn1a<sup>RH/+</sup> mice into a severe DS-like phenotype, including frequent spontaneous seizures and cognitive/behavioral deficits.
Approximately 80% of patients with Dravet syndrome have been associated with heterozygous mutations in SCN1A gene encoding voltage-gated sodium channel (VGSC) α(I) subunit, whereas a homozygous mutation (p.Arg125Cys) of SCN1B gene encoding VGSC β(I) subunit was recently described in a patient with Dravet syndrome.
These findings demonstrate that electrophysiological data from mammalian expression systems can serve as useful disease biomarker when evaluating SCN1A variants, particularly in view of new and emerging treatment options in DS.
Our results indicate that reduced sodium currents in GABAergic inhibitory interneurons in Scn1a+/- heterozygotes may cause the hyperexcitability that leads to epilepsy in patients with SMEI.
We studied concordant and discordant monozygous twins with de novo mutations in the sodium channel α1 subunit gene (SCN1A) causing Dravet's syndrome, a severe epileptic encephalopathy.
Our data provide evidence for a range of SCN1A functional abnormalities in SMEI, including gain-of-function defects that were not anticipated in this disorder.
The well established role of de novo mutations of sodium channel SCN1A in Dravet Syndrome supports this view, but the etiology of many cases of epileptic encephalopathy remains unknown.
Complete loss of function in the Na(v) 1.1 channel encoded by the SCN1A gene is associated with severe myoclonic epilepsy in infancy (SMEI), a devastating infantile-onset epilepsy with ataxia, cognitive dysfunction, and febrile and afebrile seizures resistant to current medications.
We expand the phenotypic spectrum of established epilepsy genes by reporting a familial LAMC3 homozygous variant, where the predominant phenotype was epilepsy with myoclonic-atonic seizures, and a pathogenic SCN1A variant in a family where in 5 siblings the phenotype was broadly consistent with Dravet syndrome, a disorder that usually occurs sporadically.
We describe a distinctive speech, language, and oral motor phenotype in children and adults with DS associated with mutations in <i>SCN1A.</i> Recognizing this phenotype will guide therapeutic intervention in patients with DS.
Zebrafish with a mutation in the SCN1A homologue recapitulate spontaneous seizure activity and mimic the convulsive behavioural movements observed in Dravet syndrome.
Pathogenic significance of SCN1A splicing variants causing Dravet syndrome: Improving diagnosis with targeted sequencing for variants by in silico analysis.