SCN5A Research Articles

Clinical characteristics and genetic analysis of pediatric patients with sodium channel gene mutation-related childhood epilepsy: a review of 94 patients.

This study aimed to examine the clinical and gene-mutation characteristics of pediatric patients with sodium channel gene mutation-related childhood epilepsy and to provide a basis for precision treatment and genetic counseling. The clinical data from 94 patients with sodium channel gene mutation-related childhood epilepsy who were treated at Hunan Children's Hospital from August 2012 to December 2022 were retrospectively evaluated, and the clinical characteristics, gene variants, treatment, and follow-up status were analyzed and summarized. Our 94 pediatric patients with sodium channel gene variant-related childhood epilepsy comprised 37 girls and 57 boys. The age of disease onset ranged from 1 day to 3 years. We observed seven different sodium channel gene variants, and 55, 14, 9, 6, 6, 2, and 2 patients had SCNlA, SCN2A, SCN8A, SCN9A, SCN1B, SCN11A, and SCN3A variants, respectively. We noted that 52 were reported variants and 42 were novel variants. Among all gene types, SCN1A, SCN2A, and SCN8A variants were associated with an earlier disease onset age. With the exception of the SCN1B, the other six genes were associated with clustering seizures. Except for variants SCN3A and SCN11A, some patients with other variants had status epilepticus (SE). The main diagnosis of children with SCN1A variants was Dravet syndrome (DS) (72.7%), whereas patients with SCN2A and SCN8A variants were mainly diagnosed with various types of epileptic encephalopathy, accounting for 85.7% (12 of 14) and 88.9% (8 of 9) respectively. A total of five cases of sudden unexpected death in epilepsy (SUDEP) occurred in patients with SCN1A, SCN2A, and SCN8A variants. The proportion of benign epilepsy in patients with SCN9A, SCN11A, and SCN1B variants was relatively high, and the epilepsy control rate was higher than the rate of other variant types. Sodium channel gene variants involve different epileptic syndromes, and the treatment responses also vary. We herein reported 42 novel variants, and we are also the first ever to report two patients with SCN11A variants, thereby increasing the gene spectrum and phenotypic profile of sodium channel dysfunction. We provide a basis for precision treatment and prognostic assessment.

Brugada syndrome: variability of clinical and genetic characteristics

AIM: To evaluate the clinical characteristics of patients with diverse genetic variants of Brugada syndrome.
 MATERIALS AND METHODS: 24 patients (17 male and 7 female) aged 18 to 55 years (median age 32.5 [20; 42] years) with a pattern of Brugada syndrome on electrocardiogram were observed for 3 years. From their ECGs, a type 1 pattern was found in 9 (37.5%) of these patients, type 2 pattern in 14 (58.3%) and type 3 pattern only in 1 patient. The clinical and instrumental study included 12-lead electrocardiogram, 24-hour Holter electrocardiogram monitoring, provocative drug test with intravenous administration of sodium channel blockers (novocainamide), electrophysiologic study according to indications, genealogical history collection and family history of sudden cardiac death, transthoracic echocardiography and cardiac magnetic resonance imaging to detect structural myocardial changes. High-throughput sequencing was utilized to search for mutations in genes linked to the onset of channelopathies and other inherited rhythm disorders.
 RESULTS: In 15 (62.5%) of the 24 probands included in the study, variants of the nucleotide sequence of pathogenicity classes III–V according to The American College of Medical Genetics and Genomics criteria (2015) were found in genes encoding sodium (SCN5A, SCN10A) and potassium (KCNE3, KCNJ2, KCNJ8, KCNA5) channels, as well as in HCN4 and SNTA1 genes linked with these channels. Moreover, 3 variants were identified in ANK2 gene associated with ankyrinopathies, and 3 variants in DSP and DES genes connected with arrhythmogenic right ventricular cardiomyopathy. Four genetic variants in SCN5A gene were of pathogenicity classes IV and V, the rest were variants of uncertain clinical significance (class III). Six (40.0%) of the 15 genotype-positive patients had several genetic variants. The most severe form of the disease, manifested by the development of ventricular fibrillation with successful resuscitation and subsequent cardioverter-defibrillator implantation, was observed in patients with mutations in SCN5A, SCN10A genes. Recurrent syncope, polymorphic ventricular tachycardia induced by programmed ventricular stimulation during electrophysiologic study, followed by cardioverter-defibrillator implantation were observed in patients with variants KCNJ8 and HCN4, DES and MYH11. In 2 patients with clinical manifestations, no mutations were identified. 13 (54.2%) patients were asymptomatic, while 3 of them had pathogenic and likely pathogenic mutations in SCN5A gene, as well as variants of uncertain clinical significance.
 CONCLUSION: Thus, this study examined various genetic variants in patients with Brugada syndrome based on their clinical manifestation. The impact of the genotype on the Brugada syndrome phenotype is not unambiguous. The most severe form of the disease with the development of ventricular fibrillation and successful resuscitation with subsequent cardioverter-defibrillator implantation was observed mainly in patients with variants in several genes (SCN5A and JUP, KCNJ8 and HCN4, DES and MYH11). This substantiate the idea that Brugada syndrome, along with monogenic, may also have a polygenic nature of the disease, in which the clinical phenotype is determined by variants in respective genes linked to the onset of cardiovascular disorders.

Patients with epileptic encephalopathy due to mutation in the SCN1A gene - from antecedents to clinical and laboratory findings

Patients with epileptic encephalopathy due to mutation in the SCN1A gene - from antecedents to clinical and laboratory findings

Dynamic Foraging Behavior Performance Is Not Affected by Scn2a Haploinsufficiency.

Dysfunction in the gene SCN2A, which encodes the voltage-gated sodium channel Nav1.2, is strongly associated with neurodevelopmental disorders including autism spectrum disorder and intellectual disability (ASD/ID). This dysfunction typically manifests in these disorders as a haploinsufficiency, where loss of one copy of a gene cannot be compensated for by the other allele. Scn2a haploinsufficiency affects a range of cells and circuits across the brain, including associative neocortical circuits that are important for cognitive flexibility and decision-making behaviors. Here, we tested whether Scn2a haploinsufficiency has any effect on a dynamic foraging task that engages such circuits. Scn2a +/- mice and wild-type (WT) littermates were trained on a choice behavior where the probability of reward between two options varied dynamically across trials and where the location of the high reward underwent uncued reversals. Despite impairments in Scn2a-related neuronal excitability, we found that both male and female Scn2a +/- mice performed these tasks as well as wild-type littermates, with no behavioral difference across genotypes in learning or performance parameters. Varying the number of trials between reversals or probabilities of receiving reward did not result in an observable behavioral difference, either. These data suggest that, despite heterozygous loss of Scn2a, mice can perform relatively complex foraging tasks that make use of higher-order neuronal circuits.

Non-pharmacological therapeutic needs in people with Dravet syndrome

Dravet syndrome (DS) is a genetic rare disease, which is usually caused by a mutation in the SCN1A gene. DS is characterised by a drug-resistant epilepsy and by cognitive and behavioural disturbances. Thus, DS patients require both pharmacological and non-pharmacological treatments. However, there is a paucity of studies on non-pharmacological therapies and their potential benefits. The main aim of this study was to describe the non-pharmacological therapy modalities received by DS patients and their socio-economic impact on the family. Thus, we designed an online survey addressed to caregivers of DS patients. Our results indicated that up to 91.9% of the surveyed patients required non-pharmacological therapies, which were mainly directed to treat cognitive, sensory and motor impairments. In many cases, the economic costs of these therapies were borne entirely by the families. Nevertheless, patients required a deployment of resources not only at a health care level, but also at an educational level.

Bilateral and synchronous “dents de scie” spikes: A highly specific EEG pattern of young adult Dravet syndrome

BackgroundIn Dravet syndrome (DS), EEGs evolve over time. ObjectiveTo describe a peculiar EEG pattern in two adults with a de novo SCN1A gene mutation, in exon 5 (case 1) and 9 (case 2). MethodsTwo female patients underwent a prolonged video EEG (24 h) as part of their epilepsy assessment. ResultsIn both cases, the EEG showed a very peculiar and stereotypical pattern of bilateral synchronous spikes at about 5–6 Hz. This activity was present during wakefulness and highly activated at sleep onset and in NREM sleep, which could show nearly continuous spike activity. This activity dramatically decreased in REM sleep and after awakening. This pattern of “dents de scie” (sawtooth) spikes maintained the same morphology throughout the entire EEG recording. In both patients, the spikes were favored by passive eye closure. During wakefulness, the spikes could evolve into atypical absences while keeping the same “dents de scie” pattern. Neither patient had tonic or myoclonic seizures at the time of the EEG assessment. Both were moderately retarded, and neither one had a typical DS gait disorder. Previous EEG recordings of case 1 performed at 9.5 and 18.5 years showed spike-waves, but the morphology did not correspond to the EEG recording observed at 22 years. ConclusionsBoth patients have a similar electro-clinical phenotype. This “dents de scie” pattern appears to be very specific and could be pathognomonic in a subgroup of young adults with DS. Results of sleep EEG recording could be added to the diagnostic criteria for this syndrome.

Challenges in Brugada Syndrome Stratification: Investigating SCN5A Mutation Localization and Clinical Phenotypes

Brugada Syndrome (BrS) is a genetic heart condition linked to sudden cardiac death. Though the SCN5A gene is primarily associated with BrS, there is a lack of comprehensive studies exploring the connection between SCN5A mutation locations and the clinical presentations of the syndrome. This study aimed to address this gap and gain further understanding of the syndrome. The investigation classified 36 high-risk BrS patients based on SCN5A mutations within the transmembrane/structured (TD) and intra-domain loops (IDLs) lacking a 3D structure. We characterized the intrinsically disordered regions (IDRs) abundant in IDLs, using bioinformatics tools to predict IDRs and post-translational modifications (PTMs) in NaV1.5. Interestingly, it was found that current predictive tools often underestimate the impacts of mutations in IDLs and disordered regions. Moreover, patients with SCN5A mutations confined to IDL regions—previously deemed ‘benign’—displayed clinical symptoms similar to those carrying ‘damaging’ variants. Our research illuminates the difficulty in stratifying patients based on SCN5A mutation locations, emphasizing the vital role of IDLs in the NaV1.5 channel’s functioning and protein interactions. We advocate for caution when using predictive tools for mutation evaluation in these regions and call for the development of improved strategies in accurately assessing BrS risk

Deciphering the impact of coding and non-coding SCN1A gene variants on RNA splicing.

Variants that disrupt normal pre-mRNA splicing are increasingly being recognized as a major cause of monogenic disorders. The SCN1A gene, a key epilepsy gene that is linked to various epilepsy phenotypes, is no exception. Approximately 10% of all reported variants in the SCN1A gene are designated as splicing variants, with many located outside of the canonical donor and acceptor splice sites, and most have not been functionally investigated. However, given its restricted expression pattern, functional analysis of splicing variants in the SCN1A gene could not be routinely performed. In this study, we conducted a comprehensive analysis of all reported SCN1A variants and their potential to impact SCN1A splicing and conclude that splicing variants are substantially misannotated and under-represented. We created a splicing reporter system consisting of 18 splicing vectors covering all 26 protein-coding exons with different genomic contexts and several promoters of varying strengths in order to reproduce the wild-type splicing pattern of the SCN1A gene, revealing cis-regulatory elements essential for proper recognition of SCN1A exons. Functional analysis of 95 SCN1A variants was carried out, including all 68 intronic variants reported in the literature, located outside of the splice sites canonical dinucleotides; 21 exonic variants of different classes (synonymous, missense, nonsense and in-frame deletion) and six variants observed in patients with epilepsy. Interestingly, almost 20% of tested intronic variants had no influence on SCN1A splicing, despite being reported as causative in the literature. Moreover, we confirmed that the majority of predicted exonic variants affect splicing unravelling their true molecular mechanism. We used functional data to perform genotype-phenotype correlation, revealing distinct distribution patterns for missense and splice-affecting 'missense' variants and observed no difference in the phenotype severity of variants leading to in-frame and out-of-frame isoforms, indicating that the Nav1.1 protein is highly intolerant to structural variations. Our work demonstrates the importance of functional analysis in proper variant annotation and provides a tool for high-throughput delineation of splice-affecting variants in SCN1A in a whole-gene manner.

Type 3 long QT syndrome: Is the effectiveness of treatment with beta-blockers population-specific?

BackgroundThe efficacy of beta-blocker treatment in type 3 long QT syndrome (LQT3) remains debated. ObjectivesThe purpose of this study was to test the hypothesis that beta-blocker use is associated with cardiac events (CEs) in a French cohort of LQT3 patients. MethodsAll patients with a likely pathogenic/pathogenic variant in the SCN5A gene (linked to LQT3) were included and followed-up. Documented ventricular tachycardia/ventricular fibrillation, torsades de pointes, aborted cardiac arrest, sudden death, and appropriate shocks were considered as severe cardiac events (SCEs). CEs also included syncope. ResultsWe included 147 patients from 54 families carrying 23 variants. Six of the patients developed symptoms before the age of 1 year and were analyzed separately. The 141 remaining patients (52.5% male; median age at diagnosis 24.0 years) were followed-up for a median of 11 years. The probabilities of a CE and an SCE from birth to the age of 40 were 20.5% and 9.9%, respectively. QTc prolongation (hazard ratio [HR] 1.12 [1.0–1.2]; P = .005]) and proband status (HR 4.07 [1.9–8.9]; P <.001) were independently associated with the occurrence of CEs. Proband status (HR 8.13 [1.7–38.8]; P = .009) was found to be independently associated with SCEs, whereas QTc prolongation (HR 1.11 [1.0–1.3]; P = .108) did not reach statistical significance. The cumulative probability of the age at first CE/SCE was not lower in patients treated with a beta-blocker. ConclusionIn agreement with the literature, proband status and lengthened QTc were associated with a higher risk of CEs. Our data do not show a protective effect of beta-blocker treatment.

Unexpectedly high prevalence of structural genomic variations in the Long QT Syndrome: evidence for broader clinical uptake

Abstract Background Long QT syndrome (LQTS) is an inherited channelopathy predisposing young and otherwise healthy individuals to ventricular arrhythmias causing syncope or sudden cardiac death. Point mutations in the KCNQ1, KCNH2, and SCN5A genes are the most common causes of LQTS, and up to 75% of patients can be genotyped by standard DNA sequencing. However, standard genetic testing fails to detect structural genomic rearrangements - including large deletions or duplications of DNA segments - known as copy number variants (CNVs). While previous studies suggested that CNVs account for less than 5% of genotype-negative cases(1-2), no recent data have been reported. Purpose The study aimed to determine the prevalence and spectrum of CNVs in LQTS susceptibility genes in unrelated patients who tested negative for point mutations in a panel of 16 genes associated with LQTS. Methods Next-generation sequencing (NGS) was used to screen CNVs in unrelated, clinically diagnosed LQTS patients without point mutations in 16 genes associated with LQTS. Loss of heterozygosity in LQTS-associated genes was used to assess the presence of CNVs using standard commercial software. The multiplex ligation-dependent probe amplification (MLPA) assay was used to confirm the CNVs identified by NGS. Results The cohort included 48 patients (63% women; mean age 31±19 years, range 3 years to 68 years) with definitive clinical diagnosis of LQTS (mean QTc 490±33 ms) according to the 2022 ESC guidelines(3). Overall, 7/48 patients (15%, 95% CI 6-28%) had CNVs. Six of the seven CNVs involved KCNQ1 in the heterozygous state, including three large deletions (exons 3-6, exons 12-15, and exon 16) and three duplications (exon 2, exons 3-6, and exons 3-15), whereas the remaining patient had a complete KCNH2 deletion. MLPA confirmed all CNVs identified by NGS. Of note, no CNVs were identified in LQTS-related genes whose pathogenicity has been questioned. Conclusions Our study highlights the unexpectedly high prevalence of structural genomic rearrangements in the KCNQ1 and KCNH2 genes in LQTS patients. Routine screening for copy number variants in LQTS patients is critical for accurate diagnosis, risk stratification, and personalized treatment strategies.Figure 1

A non-coding SCN5A variant that reduces sodium channel function in hiPSC-derived cardiomyocytes is significantly enriched in Brugada syndrome patients from Thailand

Abstract Background/Introduction Brugada syndrome (BrS) is an inherited arrhythmia condition that can cause sudden cardiac death. Rare coding and common non-coding genetic variation in the Nav1.5 cardiac sodium channel-encoding SCN5A gene is robustly associated with BrS, but the role of rare and low frequency non-coding variants remains unexplored. BrS is several times more prevalent in Southeast Asia compared to other populations, indicating ancestry-specific genetic risk factors remain to be discovered. Purpose To identify and characterise novel genetic risk factors in BrS patients from Southeast Asia. Methods We performed genome sequencing in 231 BrS probands from Thailand and 500 population-matched controls to identify novel disease associated variants across the entire SCN5A locus. The candidate variant was engineered into human induced pluripotent stem cells (hiPSCs) by CRISPR-Cas9 and its effect was evaluated by single cell electrophysiology analysis on hiPSC-derived cardiomyocytes. Results We identified a rare (absent in gnomAD), non-coding variant in a regulatory element of the SCN5A gene (GRCh38:3-38580380-A-C) that was significantly enriched in cases (3.9%) vs controls (0.2%) (OR=20.2[2.5-160.6], p=2e-04). Transcription factor motif scanning analysis suggested the variant is likely to disrupt a Mef2 site that is conserved across species (Figure 1) – the MEF2 family of transcription factors play a critical role in cardiac transcriptional regulation. In hiPSC-derived cardiomyocytes, a significant reduction of peak Nav1.5-mediated sodium-current (INa) density (30% decrease at -20mV, p=8e-03), without changes in gating properties, was observed in cardiomyocytes carrying the variant in heterozygosity compared to isogenic controls (Figure 2). The variant also significantly reduced luciferase activity of the candidate regulatory element in HEK cells in the presence of cardiac transcription factors (Tbx5, Gata4, Mef2A, Mef2D). Conclusion A novel, non-coding variant in an SCN5A enhancer region is associated with BrS and was functionally validated using single cell electrophysiology in hiPSC-derived cardiomyocytes. This variant is found in ∼1 in every 25 BrS patients from Thailand and therefore may at least partially explain the increased prevalence of BrS in this region. Our study highlights the importance of research in understudied populations to understand the genetic aetiology of disease in diverse ancestries and to identify novel disease risk factors.

A genetic polymorphism on chromosome 4q25 (rs17570669_T) may predict atrial fibrillation recurrence after successful electrical cardioversion

Abstract Background Direct current electrical cardioversion (DCCV), is an effective treatment method in patients with symptomatic persistent atrial fibrillation (AF). However, AF recurrence may occur following successful DCCV in nearly half of the patients. There is not enough data investigating the association between single nucleotide polymorphisms (SNP) and AF recurrence after DCCV. Purpose We aimed to investigate whether 11 SNPs previously associated with AF (rs2200733, rs10033464, rs6838973, rs3853445 and rs17570669 SNPs in PITX2 gene; rs2106261 SNP in ZFHX3 gene; rs751141 SNP on chromosome 8q21; rs3807989 SNP in CAV1 gene; rs10570248 SNP in TBX5 gene; rs1800469 SNP in TGF-1 gene; and rs6795970 SNP in SCN10A gene) were predictive for recurrence after successful DCCV in patients with persistent AF in Turkish society. Methods We included 75 patients with sinus rhythm after direct current electrical cardioversion (DCCV). Baseline clinical features and 11 AF-related SNPs were compared between patients with and without AF recurrence during the follow-up. The association between SNPs and AF recurrence was evaluated with the additive model (wild type vs heterozygous variant vs homozygous variant), the dominant model (wild type/heterozygous vs homozygous variant), and the recessive model (wild type vs heterozygous variant/homozygous variant). Results The mean age of the patients was 61.9 ± 11.5 years. At a mean follow-up of 17.0 (11.0-25.0) months, 38 patients (50.7%) developed AF recurrence. The frequency of the female gender was higher (55.3% vs. 32.4%), AF duration before DCCV was longer [9.2 (5.5-11.6) vs 5.0 (2.7-11.0) months], and left atrial volume index before DCCV was higher (43.6 ± 8.8 ml/m2 vs. 38.2 ± 12.9 ml/m2) in patients who developed AF recurrence than those without it (p=0.046, 0.029 and 0.036, respectively) (Figure 1a). In the additive model, a SNP at the PITX2 gene (rs17570669_T: OR 9.00, 95% CI 1.28-63.02, p=0.027) and a SNP at the ZFHX3 gene (rs2106261_T: OR 8.96, 95% CI 1.03-77.66, p=0.047) were significantly associated with AF recurrence. Female gender (HR: 1.99, 95% CI: 1.05-3.79, p=0.035) and the rs17570669_T SNP (HR: 4.16, 95% CI: 1.22-14.11, p=0.022) were predictors for AF recurrence in univariate analysis. A multivariate Cox regression analysis showed that the rs17570669_T SNP was an independent predictor of AF recurrence following successful DCCV in the additive model (HR: 3.59, 95% CI: 1.05-12.21, p=0.04) (Figure 1b). A Kaplan-Meier curve showed that AF-free survival was significantly lower in patients who had rs17570669_T SNP in the additive model (Figure 2). Conclusion A SNP at the PITX2 locus (rs17570669_T) may predict AF recurrence after successful DCCV in patients with persistent AF in Turkish society. Such individuals may be closely monitored for the development of AF recurrence after DCCV. In addition, reversible risk factors associated with AF recurrence may be more tightly controlled in such patients.Baseline features and Cox analysisKaplan-Meier curve

Population-specific and cross-ancestry genome-wide association study identifies shared genetic architecture and 6 new risk loci including CAMK2D associated for Brugada syndrome

Abstract Introduction The Brugada syndrome (BrS) is an inherited arrhythmia characterized by coved-type ST-segment elevation in the right precordial leads and an increased risk for sudden cardiac death. Genome-wide association studies (GWAS) of BrS, mainly performed in European ancestry, have illustrated its complex genetic architecture as an polygenic disease besides a monogenic trait due to mutations in the major responsible cardiac sodium channel gene SCN5A. Clinical manifestations of BrS including the disease prevalence and the incidence of sudden death are known to be variable between Asian and European populations, however, its underlying mechanisms are largely unknown. Objectives We aimed to identify novel BrS-associated loci and to assess ancestry-dependent genetic heterogeneity that may underlie the variable clinical manifestations of BrS patients across different populations. Methods We performed a genome-wide meta-analysis of BrS in the Japanese ancestry (940 cases and 1,634 controls), followed by a cross-ancestry meta-analysis of Japanese and European GWAS (total of 3,760 cases and 11,635 controls) to identify novel risk loci and compared the allelic effects between two ancestries. We characterized the novel loci based on fine-mapping of potential causal variants, and expression and splicing quantitative trait associations using the Genotype-Tissue Expression (GTEx) database. Results The Japanese-specific genome-wide meta-analysis identified a novel association signal near the ZSCAN20 (lead variant, rs2336244; P=1.0E-08) besides previously reported 4 association signals at the SCN5A-SCN10A and HEY2 loci. Cross-ancestry genome-wide meta-analysis identified 17 association signals including 6 novel loci. The effect directions were consistent for 94.1% of the variants (16 of 17; P for sign test = 0.00027) and their allelic effects were highly correlated across ancestries (Pearson’s R=0.91 [P=2.9E-07]). The genetic risk score (GRS) derived from European-ancestry GWAS of BrS was significantly associated with the risk of BrS in the Japanese populations (odds ratio, 2.12 [95% confidence interval, 1.94–2.31]; P=1.2E-61), suggesting the shared genetic architecture across ancestries. The functional characterization of the 6 novel loci showed that one lead SNP on CAMK2D promotes an alternative splicing resulting in an isoform switch of calmodulin kinase II that favors up-regulation of the pro-inflammatory isoform δ9 and down-regulation of the pro-survival isoform δ3. Conclusions Our results identified 6 novel susceptible loci associated with BrS and revealed shared genetic architecture across ancestries.GWAS Manhattan plotShared genetic architecture

Abstract 11661: Genotypic and Phenotypic Guided Antiarrhythmic Drug Management of Multifocal Premature Ventricular Contractions

Introduction: Antiarrhythmic selection for progressive and intractable PVCs unresponsive to first and second line regimens can prove challenging. Genetic analysis assists by targeting specific genes, such as the SCN5a gene, which encodes for the alpha subunit of cardiac sodium channel NaV1.5. Mutations are associated with autosomal dominant phenotypes of multifocal ectopic Purkinje-related premature Contractions (MEPPCs). Case: A 38 year old female with a history of syncope and moderate left ventricular systolic dysfunction status post AICD and a family history of SCD presented for follow-up with complaints of frequent palpitations. ECG and a 72 hour Holter monitor had multifocal PVCs of purkinje origin with a burden of 31%. Despite a therapeutic trial with sotalol and amiodarone in various doses, she remained unresponsive with multifocal purkinje-related PVCs. TTE revealed global LV hypokinesia with worsening LVEF, and a cardiac MRI revealed features suggestive of a dilated cardiomyopathy (DCM) phenotype. Whole exome DNA analysis showed a heterozygous missense mutation pArg814Tryp on exon 16 of the SCN5A gene. Her specific variant, R814W, is a gain-of-function variant responsible for the hyperexcitability of the Purkinje fibers, making it amenable to sodium channel blockade with flecainide. After starting gene-directed flecainide, her PVC burden drastically reduced from 31% to 3% on repeat Holter monitor after 2 months. She has remained asymptomatic with an improved LVEF. Discussion: This is a unique case of SCN5A channelopathy with a MEPPC phenotype demonstrating a dramatic response to genotype guided management of multifocal PVCs. Clinicians should include such phenotypes in their differentials for patients that fail first and second line treatment regimens and have significant family history. It is essential to offer genetic testing to patients with a MEPPC phenotype in a DCM setting to choose the appropriate therapy and prevent SCD.

Peripheral Pain Captured Centrally: Altered Brain Morphology on MRI in Small Fiber Neuropathy Patients With and Without an SCN9A Gene Variant

The current study aims to characterize brain morphology of pain as reported by small fiber neuropathy (SFN) patients with or without a gain-of-function variant involving the SCN9A gene and compare these with findings in healthy controls without pain. The Neuropathic Pain Scale was used in patients with idiopathic SFN (N = 20) and SCN9A-associated SFN (N = 12) to capture pain phenotype. T1-weighted, structural magnetic resonance imaging (MRI) data were collected in patients and healthy controls (N = 21) to 1) compare cortical thickness and subcortical volumes and 2) quantify the association between severity, quality, and duration of pain with morphological properties. SCN9A-associated SFN patients showed significant (P < .017, Bonferroni corrected) higher cortical thickness in sensorimotor regions, compared to idiopathic SFN patients, while lower cortical thickness was found in more functionally diverse regions (eg, posterior cingulate cortex). SFN patient groups combined demonstrated a significant (Spearman’s ρ = .44–.55, P = .005–.049) correlation among itch sensations (Neuropathic Pain Scale-7) and thickness of the left precentral gyrus, and midcingulate cortices. Significant associations were found between thalamic volumes and duration of pain (left: ρ = −.37, P = .043; right: ρ = −.40, P = .025). No associations were found between morphological properties and other pain qualities. In conclusion, in SCN9A-associated SFN, profound morphological alterations anchored within the pain matrix are present. The association between itch sensations of pain and sensorimotor and midcingulate structures provides a novel basis for further examining neurobiological underpinnings of itch in SFN. PerspectiveCortical thickness and subcortical volume alterations in SFN patients were found in pain hubs, more profound in SCN9A-associated neuropathy, and correlated with itch and durations of pain. These findings contribute to our understanding of the pathophysiological pathways underlying chronic neuropathic pain and symptoms of itch in SFN.

Exome analysis focusing on epilepsy-related genes in children and adults with sudden unexplained death

PurposeGenetic studies in sudden infant death syndrome (SIDS) and sudden unexplained death (SUD) cohorts have indicated that cardiovascular diseases might have contributed to sudden unexpected death in 20–35 % of autopsy-negative cases. Sudden unexpected death can also occur in people with epilepsy, termed as sudden unexpected death in epilepsy (SUDEP). The pathophysiological mechanisms of SUDEP are not well understood, but are likely multifactorial, including seizure-induced hypoventilation and arrhythmias as well as genetic risk factors. The sudden death of some of the SIDS/SUD victims might also be explained by genetic epilepsy, therefore this study aimed to expand the post-mortem genetic analysis of SIDS/SUD cases to epilepsy-related genes. MethodsExisting whole-exome sequencing data from our 155 SIDS and 45 SUD cases were analyzed, with a focus on 365 epilepsy-related genes. Nine of the SUD victims had a known medical history of epilepsy, seizures or other underlying neurological conditions and were therefore classified as SUDEP cases. ResultsIn our SIDS and SUD cohorts, we found epilepsy-related pathogenic/likely pathogenic variants in the genes OPA1, RAI1, SCN3A, SCN5A and TSC2. ConclusionPost-mortem analysis of epilepsy-related genes identified potentially disease-causing variants that might have contributed to the sudden death events in our SIDS/SUD cases. However, the interpretation of identified variants remains challenging and often changes over time as more data is gathered. Overall, this study contributes insight in potentially pathophysiological epilepsy-related mechanisms in SIDS, SUD and SUDEP victims and underlines the importance of sensible counselling on the risk and preventive measures in genetic epilepsy.

A Case Report of Type 1 Brugada Syndrome with Scn5a Mutation Augmented by Fever

Brugada syndrome is an inherited disorder characterized by a channelopathy of cardiac sodium, potassium, and calcium channel. The pathophysiology of this disorder is not completely elucidated yet, however, most of the reported cases are caused by a pathogenic alteration in the SCN5A gene, leading to the malfunction of cardiac sodium channels. Three ECG patterns are frequently described in the literature, type 1, type 2, and type 3. However, only the type 1 pattern is considered diagnostic of Brugada syndrome in the appropriate clinical context. Therapeutic strategies can range from conservative medical management with antiarrhythmic medications to Implantable Cardioverter Defibrillator placement. Prompt recognition is of utmost importance since this pathology can rapidly evolve into life-threatening arrhythmias and sudden cardiac death. Here we present a case of a 20-year-old male who presented after a surgery and with clinical findings of Brugada syndrome in which the patient suffered from brain damage post-resuscitation due to cardiac arrest.

Transcranial static magnetic stimulation reduces seizures in a mouse model of Dravet syndrome

Dravet syndrome is a rare form of severe genetic epilepsy characterized by recurrent and long-lasting seizures. It appears around the first year of life, with a quick evolution toward an increase in the frequency of the seizures, accompanied by a delay in motor and cognitive development, and does not respond well to antiepileptic medication. Most patients carry a mutation in the gene SCN1A encoding the α subunit of the voltage-gated sodium channel Nav1.1, resulting in hyperexcitability of neural circuits and seizure onset. In this work, we applied transcranial static magnetic stimulation (tSMS), a non-invasive, safe, easy-to-use and affordable neuromodulatory tool that reduces neural excitability in a mouse model of Dravet syndrome. We demonstrate that tSMS dramatically reduced the number of crises. Furthermore, crises recorded in the presence of the tSMS were shorter and less intense than in the sham condition. Since tSMS has demonstrated its efficacy at reducing cortical excitability in humans without showing unwanted side effects, in an attempt to anticipate a possible use of tSMS for Dravet Syndrome patients, we performed a numerical simulation in which the magnetic field generated by the magnet was modeled to estimate the magnetic field intensity reached in the cerebral cortex, which could help to design stimulation strategies in these patients. Our results provide a proof of concept for nonpharmacological treatment of Dravet syndrome, which opens the door to the design of new protocols for treatment.

SCN8A epileptic encephalopathy: literature review and own observation

A genetic disease caused by pathogenetic nucleotide variants in the SCN8A gene (Sodium channel protein type 8 subunit alpha, also known as Nav1.6), encoding the α-subunit of the Na channel type 8, is included in the group of early epileptic encephalopathies. In most cases, this pathology is characterized by the development of polymorphic pharmacoresistant epileptic seizures over the first year of a child’s life, a lag in psychomotor development or regression, loss of skills. In some patients, seizures may appear during the first days of life, while in others they appear later (at the age of 2 to 7 months), against the background of a pronounced or slight developmental delay. Types of seizures may include generalized, tonic-clonic seizures, infantile spasms, absences and focal seizures. Other signs and symptoms of encephalopathy caused by mutations of the SCN8A gene may include low muscle tone (hypotension), high pain threshold, motor disorders (such as dystonia and ataxia), mild to severe mental retardation, sleep problems and autistic traits. In some people with SCN8A encephalopathy, various other pathological changes in the body have been reported, including hearing or vision impairment, scoliosis, and thermoregulation difficulties. The disease is inherited by an autosomal dominant type.&#x0D; To date, the disease in the OMIM system is referred to as «Developmental encephalopathy and epileptic encephalopathy type 13». Previously, the disease was called «Early infantile (infantile) epileptic encephalopathy, type 13». The serial number «13» indicates this form of early epileptic encephalopathy to be caused by a heterozygous mutation in the gene on the long arm of chromosome 12 in chromosome region 12q13.13.&#x0D; This report also presents a clinical description of a patient suffering from early infantile epileptic encephalopathy, type 13.

Reduction of Kcnt1 is therapeutic in mouse models of SCN1A and SCN8A epilepsy.

Developmental and epileptic encephalopathies (DEEs) are severe seizure disorders with inadequate treatment options. Gain- or loss-of-function mutations of neuronal ion channel genes, including potassium channels and voltage-gated sodium channels, are common causes of DEE. We previously demonstrated that reduced expression of the sodium channel gene Scn8a is therapeutic in mouse models of sodium and potassium channel mutations. In the current study, we tested whether reducing expression of the potassium channel gene Kcnt1 would be therapeutic in mice with mutation of the sodium channel genes Scn1a or Scn8a. A Kcnt1 antisense oligonucleotide (ASO) prolonged survival of both Scn1a and Scn8a mutant mice, suggesting a modulatory effect for KCNT1 on the balance between excitation and inhibition. The cation channel blocker quinidine was not effective in prolonging survival of the Scn8a mutant. Our results implicate KCNT1 as a therapeutic target for treatment of SCN1A and SCN8A epilepsy.