Mutations In SCN5A Gene Research Articles

Human macrophages directly modulate iPSC-derived cardiomyocytes at healthy state and congenital arrhythmia model in vitro.

The electrophysiological regulation of cardiomyocytes (CMs) by the cardiac macrophages (MΦs) has been recently described as an unconventional role of MΦs in the murine heart. Investigating the molecular and physiological modulation of CM by MΦ is critical to understand the novel mechanisms behind cardiac disorders from the systems perspective and to develop new therapeutic approaches. Here, we developed an in vitro direct coculture system to investigate the cellular and functional interaction between human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and monocyte-derived MΦs both in healthy-state and congenital arrhythmia disease model associated with SCN5A ion channel mutations. Congenital arrhythmia patient-derived (P) and healthy individual-derived control (C) monocytes and derived MΦs exhibited distinct M1- and M2-like polarization-related gene expression pattern. The iPSC-CMs and MΦs formed direct membrane contacts in cocultures demonstrated by time-lapse imaging, scanning electron microscopy, and immunolabeling. The intracellular Ca2+ transients were observed in iPSC-CMs and MΦs when in contact with each other. Interestingly, the C-MΦs in direct contact with C-CMs significantly accelerated the contraction rates, demonstrating the positive chronotropic effect of MΦs on healthy cardiac cultures. Furthermore, the MΦs carrying the SCN5A gene mutation significantly enhanced the arrhythmic events in both C-CMs and P-CMs, implying that the sodium channel mutation in the MΦ is important for the CM function. Importantly, when C-MΦs were coupled to tachycardic P-CMs, the contraction frequency drastically decreased, and rhythmicity enhanced implicating the amelioration of the disease phenotype in vitro. Consequently, our results indicated the functional regulatory role of MΦs on human iPSC-CM contractility by membrane contacts in a physiologically relevant in vitro coculture model of both steady-state and arrhythmia. Our findings could serve as a valuable source for the development of effective immunoregulatory therapies for cardiac arrhythmia in the future.

SCN1A gene mutation: A rising cause of human epilepsy syndrome

Epilepsy is found to be very common neurological disorder; it covers a wide range of abnormalities lying within brain. Generation of electrical activity of brain that is action potential and then its proper propagation in central nervous system (CNS) and Peripheral Nervous System (PNS) upto the target site is mandatory for the proper functioning of brain. The human sodium channel (SCN) family plays its critical role in all these neuronal mechanisms. These channels are prone to number of channelopatheis and mutations that are the key point of research and discussion now a day. About 700 mutations of SCN1A gene have been identified. This gene is considered as the commonly mutated gene in human epilepsy. This review is on the structural, functional and pathological aspects of SCN1A gene and its associated channelopathies. This will explore the advances in epilepsy genetics and may help in designing for new therapeutic modalities for treating epileptic patients.

SCN5A mutation in Brugada syndrome is associated with substrate severity detected by electrocardiographic imaging and high-density electroanatomic mapping.

Brugada syndrome (BrS) is caused by mutations in SCN5A gene in 15%-20% of cases. Previous studies showed worse prognosis in SCN5A mutation carriers (SCN5A+). To date, there are no data on genotype-phenotype correlation with electrocardiographic (ECG) imaging (ECGI) and high-density epicardial electroanatomic map. This study aimed to correlate SCN5A mutation with substrate severity in BrS assessed by ECGI and high-density electroanatomic map. All consecutive BrS patients undergoing ECGI and high-density epicardial electroanatomic map with HD Grid Mapping Catheter were retrospectively analyzed. On ECGI, the following parameters were analyzed before and after ajmaline administration: right ventricular outflow tract (RVOT) activation time (RVOT-AT) and RVOT recovery time (RVOT-RT). On electroanatomic map, the parameters analyzed before and after ajmaline were high-frequency potential activation time (HFPat), high-frequency potential duration (HFPd), high-frequency potential amplitude (HFPa), low-frequency potential activation time (LFPat), low-frequency potential duration (LFPd), and low-frequency potential amplitude (LFPa). Thirty-nine BrS patients with ECGI were included. Eight patients (20.5%) were SCN5A+. At baseline ECGI map, mean RVOT-RT was longer in SCN5A+ (P = .024). After ajmaline administration, SCN5A+ patients showed longer RVOT-AT (125.6 vs 100.8 ms; P = .045) and longer RVOT-RT (426.4 vs 397 ms; P = .033). After ajmaline administration, SCN5A+ showed longer HFPat (164.1 vs 119.5 ms; P = .041); longer LFPat (272.7 vs 200.5 ms; P=.018); and longer LFPd (211.9 vs 151.2 ms; P = .033). In BrS, SCN5A+ patients compared with SCN5A- patients exhibit marked depolarization and repolarization abnormalities as assessed by ECGI and epicardial high-density electroanatomic map.

SCN5A mutation is associated with severity of abnormalities detected by ECG imaging in Brugada syndrome

Abstract Funding Acknowledgements Type of funding sources: None. Background Brugada syndrome (BrS) is caused by mutations in SCN5A gene in 15%-20% of cases. Previous studies showed a worse prognosis in SCN5A mutation carriers (SCN5A+). Purpose To evaluate genotype-phenotype correlation with ECG imaging (ECGI). Methods All consecutive patients who underwent ECGI with CardioInsight for BrS were retrospectively analyzed. ECGI parameters analyzed before and after ajmaline administration were: 1) Right ventricular outflow tract (RVOT) activation time (RVOT-AT) and 2) RVOT recovery time (RVOT-RT). Genetic analysis was performed in all patients with SeqCap EZ Human Exome Probes v3.0 for BrS. Patients were defined as SCN5A+ if they had a pathogenic/likely pathogenic mutation in SCN5A following ACMG guidelines. Results Thirty-six BrS patients were included and 8 patients (22%) were SCN5A+. At baseline ECGI map, mean RVOT-RT was higher in SCN5A+ [384.8 ms vs 362 ms, p=0.037], with no difference in RVOT-AT (p=0.65). After ajmaline administration SCN5A+ patients showed higher RVOT-AT [125.6 ms vs 102.4 ms, p=0.045] (Figure) and higher RVOT-RT [426.4 ms vs 400 ms, p=0.038]. At univariate logistic regression, baseline RVOT-RT was a predictor of SCN5A mutation (specificity: 0.64, sensitivity 0.88, AUC 0.75). Conclusion In BrS syndrome SCN5A+ patients exhibit marked depolarization and repolarization abnormalities as assessed by ECGI.

Human iPSC Modeling of Genetic Febrile Seizure Reveals Aberrant Molecular and Physiological Features Underlying an Impaired Neuronal Activity.

Mutations in SCN1A gene, encoding the voltage-gated sodium channel (VGSC) NaV1.1, are widely recognized as a leading cause of genetic febrile seizures (FS), due to the decrease in the Na+ current density, mainly affecting the inhibitory neuronal transmission. Here, we generated induced pluripotent stem cells (iPSCs)-derived neurons (idNs) from a patient belonging to a genetically well-characterized Italian family, carrying the c.434T > C mutation in SCN1A gene (hereafter SCN1AM145T). A side-by-side comparison of diseased and healthy idNs revealed an overall maturation delay of SCN1AM145T cells. Membranes isolated from both diseased and control idNs were injected into Xenopus oocytes and both GABA and AMPA currents were successfully recorded. Patch-clamp measurements on idNs revealed depolarized action potential for SCN1AM145T, suggesting a reduced excitability. Expression analyses of VGSCs and chloride co-transporters NKCC1 and KCC2 showed a cellular “dysmaturity” of mutated idNs, strengthened by the high expression of SCN3A, a more fetal-like VGSC isoform, and a high NKCC1/KCC2 ratio, in mutated cells. Overall, we provide strong evidence for an intrinsic cellular immaturity, underscoring the role of mutant NaV1.1 in the development of FS. Furthermore, our data are strengthening previous findings obtained using transfected cells and recordings on human slices, demonstrating that diseased idNs represent a powerful tool for personalized therapy and ex vivo drug screening for human epileptic disorders.

Life Threatening Broad QRS Tachycardia in an Infant with Conduction Disorder and SCN5A Mutation

We present the case of an infant admitted to our department for a rapid broad complex tachycardia and cardiovascular collapse. The patient was submitted to genetic testing because of a conduction defect at baseline ECG and family history of gene mutation. A new SCN5A gene mutation variant was found leading to diagnosis of sodium-channel dysfunction arrhythmia.

SCN1A Mutation-Beyond Dravet Syndrome: A Systematic Review and Narrative Synthesis.

Background: SCN1A is one of the most common epilepsy genes. About 80% of SCN1A gene mutations cause Dravet syndrome (DS), which is a severe and catastrophic epileptic encephalopathy. More than 1,800 mutations have been identified in SCN1A. Although it is known that SCN1A is the main cause of DS and genetic epilepsy with febrile seizures plus (GEFS+), there is a dearth of information on the other related diseases caused by mutations of SCN1A.Objective: The aim of this study is to systematically review the literature associated with SCN1A and other non-DS-related disorders.Methods: We searched PubMed and SCOPUS for all the published cases related to gene mutations of SCN1A until October 20, 2021. The results reported by each study were summarized narratively.Results: The PubMed and SCOPUS search yielded 2,889 items. A total of 453 studies published between 2005 and 2020 met the final inclusion criteria. Overall, 303 studies on DS, 93 on GEFS+, three on Doose syndrome, nine on the epilepsy of infancy with migrating focal seizures (EIMFS), six on the West syndrome, two on the Lennox–Gastaut syndrome (LGS), one on the Rett syndrome, seven on the nonsyndromic epileptic encephalopathy (NEE), 19 on hemiplegia migraine, six on autism spectrum disorder (ASD), two on nonepileptic SCN1A-related sudden deaths, and two on the arthrogryposis multiplex congenital were included.Conclusion: Aside from DS, SCN1A also causes other epileptic encephalopathies, such as GEFS+, Doose syndrome, EIMFS, West syndrome, LGS, Rett syndrome, and NEE. In addition to epilepsy, hemiplegic migraine, ASD, sudden death, and arthrogryposis multiplex congenital can also be caused by mutations of SCN1A.

Preclinical investigation of β-caryophyllene as a therapeutic agent in an experimental murine model of Dravet syndrome

Dravet Syndrome (DS) is caused by mutations in the Scn1a gene encoding the α1 subunit of the sodium channel Nav1.1, which results in febrile seizures that progress to severe tonic-clonic seizures and associated comorbidities. Treatment with cannabidiol has been approved for the management of seizures in DS patients, but it appears to be also active against associated comorbidities. In this new study, we have investigated β-caryophyllene (BCP), a cannabinoid with terpene structure that appears to also have a broad-spectrum profile, as a useful therapy against both seizuring activity and progression of associated comorbidities. This has been studied in heterozygous conditional knock-in mice carrying a missense mutation (A1783V) in Scn1a gene expressed exclusively in neurons of the Central Nervous System (Syn-Cre/Scn1aWT/A1783V), using two experimental approaches. In the first approach, an acute treatment with BCP was effective against seizuring activity induced by pentylenetetrazole (PTZ) in wildtype (Scn1aWT/WT) and also in Syn-Cre/Scn1aWT/A1783V mice, with these last animals having a greater susceptibility to PTZ. Such benefits were paralleled by a BCP-induced reduction in PTZ-induced reactive astrogliosis (labelled with GFAP) and microgliosis (labelled with Iba-1) in the prefrontal cortex and the hippocampal dentate gyrus, which were visible in both wildtype (Scn1aWT/WT) and Syn-Cre/Scn1aWT/A1783V mice. In the second approach, both genotypes were treated repeatedly with BCP to investigate its effects on several DS comorbidities. Thus, BCP corrected important behavioural abnormalities of Syn-Cre/Scn1aWT/A1783V mice (e.g. delayed appearance of hindlimb grasp reflex, induction of clasping response, motor hyperactivity, altered social interaction and memory impairment), attenuated weight loss, and slightly delayed premature mortality. Again, these benefits were paralleled by a BCP-induced reduction in reactive astrogliosis and microgliosis in the prefrontal cortex and the hippocampal dentate gyrus typical of Syn-Cre/Scn1aWT/A1783V mice. In conclusion, BCP was active in Syn-Cre/Scn1aWT/A1783V mice against seizuring activity (acute treatment) and against several comorbidities (repeated treatment), in both cases in association with its capability to reduce glial reactivity in areas related to these behavioural abnormalities. This situates BCP in a promising position for further preclinical evaluation towards a close translation to DS patients.

Familial cardiomyopathy caused by mutation of SCN5A gene

1岁3月龄患儿因“咳嗽6 d，精神萎靡伴面色发绀2 h”就诊，诊断为左心室致密化不全、支气管肺炎、心力衰竭。该患儿存在心肌病家族史，有一胞姐3岁时死于扩张型心肌病，母亲有左心室扩大及房间隔缺损，对患儿行全外显子组基因测序发现其存在SCN5A基因杂合错义突变：c.3076C>T（p.R1023C），该突变遗传自母亲，考虑该突变可导致家族性心肌病。该突变首次在家族性心肌病中被报道。.

Lamotrigine-induced Brugada syndrome: A rare adverse event

Brugada syndrome is a rare inherited channelopathy predisposing to ventricular arrhythmias and leading to an increased risk of sudden cardiac death, despite a structurally normal heart. The most common mutation is a loss-of-function mutation in SCN5A gene, rsesponsible for encoding the α-subunit of the sodium channel. Diagnosis is based on a specific electrocardiogram (ECG) pattern, observed either spontaneously or during a sodium channel blocker test. Considering the two different Brugada pattern types, type 1 is the most frequently associated with the SCN5A gene mutation [1].

P.Asn1180Ile mutation of SCN4A gene in an Italian family with myopathy and myotonic syndrome.

Mutations of the skeletal muscle sodium channel gene SCN4A are associated with several neuromuscular disorders including hyper/hypokaliemic periodic paralysis, paramyotonia congenita and sodium channel myotonia. These disorders are distinguished from dystrophic myotonias by the absence of progressive weakness and extramuscular systemic involvement. We present an Italian family with 2 subjects carrying a p.Asn1180Ile mutation in SCN4A gene showing a peculiar clinical picture characterized by the association of myopathic features and myotonia. The clinical, electromyographic and histological findings of these patients are reported. The possible pathogenicity of the mutation was tested by three different software, all giving positive results. This is the first report of a dominant, heterozygous mutation in SCN4A causing a complex phenotype of non-congenital myopathy and myotonic syndrome. We suggest that, in patients with myotonia and myopathy not related to dystrophic myotonias, the sequence analysis of SCN4A gene should be performed.

B-PO02-216 MONOMORPHIC VENTRICULAR TACHYCARDIA FOLLOWING VENTRICULAR FIBRILLATION ABLATION IN BRUGADA SYNDROME

Radiofrequency (RF) epicardial RV/RV outflow tract (RVOT) substrate ablation can normalize Brugada pattern ECG & reduce Ventricular Fibrillation (VF) recurrence. There is no of literature about proarrhythmic effect of ablation and scar creation. Case of monomorphic Ventricular Tachycardia (MM VT) after VF ablation for Brugada Syndrome due to ablation induced scar related re-entry. NA 47-year-old male with Brugada syndrome diagnosed after sudden cardiac death & confirmed with SCN5A gene mutation had multiple ICD therapies for VF despite high dose oral Quinidine. Cardiac MRI showed structurally normal heart & absence of scar. He underwent VF ablation where epicardial surface & endocardial RV was mapped. RV endocardium was normal. Epicardial voltage map showed area of low voltage with late potentials over anterior RVOT. IV Procainamide resulted in expansion of low voltage area. RF ablation & homogenization of this area was performed. Post procedure normalization of ECG was noted at 3 months. He did not have ICD therapies for 1 year & quinidine was tapered with no anterior precordial ECG abnormalities. 1.5 years post ablation he had presyncope & sustained MM VT. ICD intracardiac electrograms showed MM VT, stable cycle length of 250ms. Anti-tachycardia pacing terminated VT. Far field EGM morphology suggested an inferiorly directed VT. Quinidine was restarted at low dose with no recurrent arrhythmias. Documented case of monomorphic VT post epicardial substrate modification for VF in Brugada syndrome. Scar created by RF ablation on epicardial RVOT may contribute to re-entrant VT via incomplete ablation or iatrogenic scar mediated reentry.

Genetics and clinical correlation of Dravet syndrome and its mimics – experience of a tertiary center in Taiwan

Dravet syndrome is a severe developmental and epileptic encephalopathy characterized by the onset of prolonged febrile and afebrile seizures in infancy and SCN1A gene mutations. In some cases, non-SCN1A gene mutations can present with a phenotype very similar to that of Dravet syndrome. The aim of this study was to compare phenotypes of patients with SCN1A and non-SCN1A gene mutation-related Dravet syndrome. Thirty-six patients with Dravet syndrome-like phenotypes were followed from July 2017 to December 2019. We retrospectively analyzed their clinical profiles and genetic surveys. Of the 36 enrolled patients, 15 (41.7%) had SCN1A mutations, one (2.8%) had an SCN8A mutation, one (2.8%) had an STX1B mutation, and five females (13.9%) had PCDH 19 mutations. The median age at first seizure onset was 7 months in those with SCN1A mutations, 1.3 years in those with PCDH19 mutations, and 10 months for the remaining patients. The majority of the patients with SCN1A mutations had status epilepticus (80% vs. 20%) and fever-sensitive seizures (76% vs. 31%) compared to those with PCDH19 mutations. The patients with SCN1A-related seizures had a higher rate of focal seizures as first seizure type than those without SCN1A mutations. Three of five (60%) patients with PCDH19 mutations had brain magnetic resonance imaging abnormalities. The three most commonly used antiseizure medications were sodium valproate, levetiracetam, and clobazam. Seven of the 15 patients with SCN1A mutations used stiripentol. The median time from seizure onset to genetic diagnosis was 6.6 years (range 4 months-22.3 years). The patients with SCN1A mutations in this study had high rates of fever-sensitive seizures, status epilepticus, seizure onset with focal seizure type, and relatively young age at seizure onset. The patients with PCDH19 mutations had a relatively high rate of abnormal brain magnetic resonance imaging findings.

Focal epilepsy due to de novo SCN1A mutation.

Our aim was to identify patients with SCN1A-related epilepsy with a phenotype of pure focal epilepsy. We conducted a retrospective study and a systematic review in Pubmed to identify patients with focal epilepsy associated with SCN1A pathogenic variants. We found three patients among 1,191 in our rare epilepsy database in 2017. The literature search from January 2000 to September 2019 led to identification of four patients with limited data. Our three patients had a common phenotype with focal-onset seizures as the only seizure type. All patients showed normal psychomotor development in the first years of life, and no intellectual disability although they displayed some cognitive or behavioural problems. Fever or hyperthermia were triggers in all three patients. In addition, all had a history of brief recurrent febrile seizures in their first year, followed by a phenotype of pharmacoresistant focal epilepsy with normal brain imaging. Two of them were initially investigated for epilepsy surgery. Seizure precipitation by fever has also been reported in previously published patients. Focal epilepsy associated with SCN1A gene mutation should be recognized in patients with suggestive features, in particular among surgical candidates.

Single Cell Transcriptomic and Genomic Characterization of Brugada Syndrome Associated Genes

Brugada syndrome (BrS) is a rare, inherited arrhythmia with high risk of sudden cardiac death. Complex genetic background of BrS primarily involves mutations in genes encoding ion channels and regulatory/structural proteins. However, the molecular pathways and single cell expression patterns linked to clinically associated genes in BrS are not well defined. To evaluate the convergence of key genes, domains, motifs, molecular pathways, and single cell expression associated with BrS, we collected 733 mutations represented by 16 sodium, calcium, potassium channels, regulatory and structural genes related to BrS reported between 1999-2019.266 of the clinically relevant mutations (splice site, stop, frame shift and deleterious missense) in genes occurred once and 88 mutations were recurrent in nature, which appeared at two to forty-three instances. We observed an over-representation of clinically relevant mutations (~80%) in SCN5A gene, and also identified several candidate genes, including GPD1L, TRPM4, and SCN10A. Single cell transcriptomic analysis revealed restrictive expression of highly mutated BrS genes. Furthermore, protein domain enrichment analysis revealed that a large proportion of the mutations impacted ion-transport domains in multiple genes, SCN5A, TRPM4 and SCN10A. Gene enrichment analysis identified the action potential pathway as the most significant pathway involving the mutated genes in BrS. A comparative protein domain analysis of the SCN5A further established a significant (p=0.04) relation between mutation distribution and ion-transport domain. A strong association (p=0.00003) was also observed between mutation distribution across the ion transport domain and early/late onset of BrS. The significant role of the mutations in the ion transport domain leading to BrS manifestation was further established by window-based and MEME motif analysis which identified residue 1321-1380 (part of ion transport domain) as one of the significant (p=0.02) hotspot regions. Our study identified genomic and proteomic hotspots and a convergent pathway (ion transport) that provides in-depth insight into the complex pathophysiology of BrS. Single cell transcriptome profile of heart tissue shows that highly mutated genes (SCN5A and GPD1L) in BrS are restrictively expressed in ventricular cardiomyocyte cell type.

Genetics Analysis of patients with Dravet syndrome due to mosaicism variation of paternal SCN1A gene

Genetic analysis was performed on a family of fraternal twins affected with Dravet syndrome by genetic tests whose parents were normal. To further analyze the cause of the disease, the fraternal twins were subjected to whole exome sequencing (WES), and the family was verified by Sanger sequencing, with the father semen and peripheral blood DNA were further analysed by target sequencing. The WES test identified a heterozygous c.5348C>T (p.Ala1783Val) variant of the SCN1A gene in the fraternal twins, which was predicted to be pathogenic and was detected in the father peripheral blood and semen, but not in the mother. So the mosaicism mutation of paternal SCN1A gene might be the genetic cause of Dravet syndrome in offspring.

Clinical and genetic spectrum of a Chinese cohort with SCN4A gene mutations

Skeletal muscle sodium channelopathies due to SCN4A gene mutations have a broad clinical spectrum. However, each phenotype has been reported in few cases of Chinese origin. We present detailed phenotype and genotype data from a cohort of 40 cases with SCN4A gene mutations seen in neuromuscular diagnostic service in Huashan hospital, Fudan University. Cases were referred from 6 independent provinces from 2010 to 2018. A questionnaire covering demographics, precipitating factors, episodes of paralysis and myotonia was designed to collect the clinical information. Electrodiagnostic studies and muscle MRI were retrospectively analyzed. The clinical spectrum of patients included: 6 Hyperkalemic periodic paralysis (15%), 18 Hypokalemic periodic paralysis (45%), 7 sodium channel myotonia (17.5%), 4 paramyotonia congenita (10%) and 5 heterozygous asymptomatic mutation carriers (12.5%). Review of clinical information highlights a significant delay to diagnosis (median 15 years), reports of pain and myalgia in the majority of patients, male predominance, circadian rhythm and common precipitating factors. Electrodiagnostic studies revealed subclinical myotonic discharges and a positive long exercise test in asymptomatic carriers. Muscle MRI identified edema and fatty infiltration in gastrocnemius and soleus. A total of 13 reported and 2 novel SCN4A mutations were identified with most variants distributed in the transmembrane helix S4 to S6, with a hotspot mutation p.Arg675Gln accounting for 32.5% (13/40) of the cohort. Our study revealed a higher proportion of periodic paralysis in SCN4A-mutated patients compared with cohorts from England and the Netherlands. It also highlights the importance of electrodiagnostic studies in diagnosis and segregation studies.

Mutations in the sodium channel genes SCN1A, SCN3A, and SCN9A in children with epilepsy with febrile seizures plus(EFS+)

Purpose: To explore disease-causing gene mutations of epilepsy with febrile seizures plus (EFS+) in Southern Chinese Han population.Methods: Blood samples and clinical data were collected from 49 Southern Han Chinese patients with EFS+. Gene screening was performed using whole-exome sequencing and panel sequencing for 485 epilepsy-related genes. The pathogenicity of variants was evaluated based on ACMG scoring and assessment of clinical concordance.Results: We identified 10 putatively causative sodium channel gene variants in 49 patients with EFS+, including 8 variants in SCN1A (R500Q appeared twice), one in SCN3A and one in SCN9A. All these missense mutations were inherited from maternal or paternal and were evaluated to be of uncertain significance according to ACMG. The clinical features of patients were in concordance with the EFS+ phenotype of the mutated SCN1A, SCN3A and SCN9A gene. The clinical phenotypes of 11 probands with these gene variants included febrile seizures plus (FS+, n=7), Dravet Syndrome (n=3), FS+ with focal seizures (n=1). Three probands with SCN1A variants (R500Q located in the non-voltage areas, or G1711D in the pore-forming domain) developed severe Dravet syndrome. The affected individuals with the other 6 SCN1A variants located outside the pore-forming domain showed mild phenotypes. Novel SCN3A variant ((D1688Y) and SCN9A variant (R185H) were identified in two probands respectively and both of the probands had FS+.Conclusion: The SCN1A, SCN3A, and SCN9A gene mutations might be a pathogenic cause of EFS+ in Southern Chinese Han population.

Neuropathological Characterization of a Dravet Syndrome Knock-In Mouse Model Useful for Investigating Cannabinoid Treatments.

Dravet syndrome (DS) is an epileptic syndrome caused by mutations in the Scn1a gene encoding the α1 subunit of the sodium channel Nav1.1, which is associated with febrile seizures that progress to severe tonic-clonic seizures and associated comorbidities. Treatment with cannabidiol has been approved to reduce seizures in DS, but it may also be active against these comorbidities. The aim of this study was to validate a new mouse model of DS having lower mortality than previous models, which may serve to further evaluate therapies for the long-term comorbidities. This new model consists of heterozygous conditional knock-in mice carrying a missense mutation (A1783V) in Scn1a gene expressed exclusively in neurons of the CNS (Syn-Cre/Scn1aWT/A1783V). These mice have been used here to determine the extent and persistence of the behavioral deterioration in different postnatal days (PND), as well as to investigate the alterations that the disease produces in the endocannabinoid system and the contribution of inflammatory events and impaired neurogenesis in the pathology. Syn-Cre/Scn1aWT/A1783V mice showed a strong reduction in hindlimb grasp reflex at PND10, whereas at PND25, they presented spontaneous convulsions and a greater susceptibility to pentylenetetrazole-induced seizures, marked hyperactivity, deficient spatial working memory, lower levels of anxiety, and altered social interaction behavior. These differences disappeared at PND40 and PND60, except the changes in social interaction and anxiety. The analysis of CNS structures associated with these behavioral alterations revealed an elevated glial reactivity in the prefrontal cortex and the dentate gyrus. This was associated in the dentate gyrus with a greater cell proliferation detected with Ki67 immunostaining, whereas double-labeling analyses identified that proliferating cells were GFAP-positive suggesting failed neurogenesis but astrocyte proliferation. The analysis of the endocannabinoid system of Syn-Cre/Scn1aWT/A1783V mice confirmed reductions in CB1 receptors and MAGL and FAAH enzymes, mainly in the cerebellum but also in other areas, whereas CB2 receptors became upregulated in the hippocampus. In conclusion, Syn-Cre/Scn1aWT/A1783V mice showed seizuring susceptibility and several comorbidities (hyperactivity, memory impairment, less anxiety, and altered social behavior), which exhibited a pattern of age expression similar to DS patients. Syn-Cre/Scn1aWT/A1783V mice also exhibited greater glial reactivity and a reactive response in the neurogenic niche, and regional changes in the status of the endocannabinoid signaling, events that could contribute in behavioral impairment.

Multicenter prospective longitudinal study in 34 patients with Dravet syndrome: Neuropsychological development in the first six years of life

The objective of this study was to identify developmental trajectories of developmental/behavioral phenotypes and possibly their relationship to epilepsy and genotype by analyzing developmental and behavioral features collected prospectively and longitudinally in a cohort of patients with Dravet syndrome (DS).Thirty-four patients from seven Italian tertiary pediatric neurology centers were enrolled in the study. All patients were examined for the SCN1A gene mutation and prospectively assessed from the first years of life with repeated full clinical observations including neurological and developmental examinations. Subjects were found to follow three neurodevelopmental trajectories. In the first group (16 patients), an initial and usually mild decline was observed between the second and the third year of life, specifically concerning visuomotor abilities, later progressing towards global involvement of all abilities. The second group (12 patients) showed an earlier onset of global developmental impairment, progressing towards a generally worse outcome. The third group of only two patients ended up with a normal neurodevelopmental quotient, but with behavioral and linguistic problems. The remaining four patients were not classifiable due to a lack of critical assessments just before developmental decline.The neurodevelopmental trajectories described in this study suggest a differential contribution of neurobiological and genetic factors. The profile of the first group, which included the largest fraction of patients, suggests that in the initial phase of the disease, visuomotor defects might play a major role in determining developmental decline.Early diagnosis of milder cases with initial visuomotor impairment may therefore provide new tools for a more accurate habilitation strategy.