NaV1.5 autoantibodies in Brugada syndrome: pathogenetic implications.

BACKGROUND AND AIMS: Patients suffering from Brugada syndrome (BrS) are predisposed to life-threatening cardiac arrhythmias. Diagnosis is challenging due to the elusive electrocardiographic (ECG) signature that often requires unconventional ECG lead placement and drug challenges to be detected. Although NaV1.5 sodium channel dysfunction is a recognized pathophysiological mechanism in BrS, only 25% of patients have detectable SCN5A variants. Given the emerging role of autoimmunity in cardiac ion channel function, this study explores the presence and potential impact of anti-NaV1.5 autoantibodies in BrS patients. METHODS: Using engineered HEK293A cells expressing recombinant NaV1.5 protein, plasma from 50 BrS patients and 50 controls was screened for anti-NaV1.5 autoantibodies via western blot, with specificity confirmed by immunoprecipitation and immunofluorescence. The impact of these autoantibodies on sodium current density and their pathophysiological effects were assessed in cellular models and through plasma injection in wild-type mice. RESULTS: Anti-NaV1.5 autoantibodies were detected in 90% of BrS patients vs. 6% of controls, yielding a diagnostic area under the curve of .92, with 94% specificity and 90% sensitivity. These findings were consistent across varying patient demographics and independent of SCN5A mutation status. Electrophysiological studies demonstrated a significant reduction specifically in sodium current density. Notably, mice injected with BrS plasma showed Brugada-like ECG abnormalities, supporting the pathogenic role of these autoantibodies. CONCLUSIONS: The study demonstrates the presence of anti-NaV1.5 autoantibodies in the majority of BrS patients, suggesting an immunopathogenic component of the syndrome beyond genetic predispositions. These autoantibodies, which could serve as additional diagnostic markers, also prompt reconsideration of the underlying mechanisms of BrS, as evidenced by their role in inducing the ECG signature of the syndrome in wild-type mice. These findings encourage a more comprehensive diagnostic approach and point to new avenues for therapeutic research.

Arrhythmogenic substrate elimination for safe testosterone therapy in symptomatic Brugada syndrome patients.

BACKGROUND: Brugada Syndrome (BrS) is a cardiogenetic disease known for its association with sudden cardiac death (SCD) in individuals with structurally normal hearts. The prevalence of BrS is higher in males, who also face a greater risk of SCD. Its higher prevalence and worse outcome in male subjects may be due to testosterone effects on ion channels expression and function. The influence of testosterone on cardiac action potentials, both genomically and non-genomically, underscores its potential role in unmasking the syndrome and triggering life-threatening arrhythmias. Notably, testosterone replacement therapy (TRT), used for hypogonadism and gender reassignment, has been linked to BrS unmasking. The role of epicardial ablation in symptomatic BrS patients where hormonal therapy cannot be discontinued is unknown. METHODS AND RESULTS: In this study we describe the first two cases of substrate mapping and ablation in BrS patients experiencing arrhythmic events while on TRT. In both cases, high-density epicardial mapping revealed abnormal areas of prolonged and fragmented electrograms in the right ventricular (RV) outflow tract and anterior wall. These abnormalities were completely abolished by radiofrequency ablation (RFA). After ablation, both patients showed a persistent normalization of the ECG and were free from ventricular arrhythmias at follow-up, despite ongoing TRT. CONCLUSION: RFA can be considered as a therapeutic option in symptomatic BrS patients with a high-risk profile who cannot discontinue TRT, being essential for restoring their normal physiology or preserving their sexual identity. As testosterone use is increasing, further studies are warranted to define a standardized diagnostic and therapeutic strategy in this specific subset of BrS patients.

Right ventricular epicardial arrhythmogenic substrate in long-QT syndrome patients at risk of sudden death.

AIMS: The long-QT syndrome (LQTS) represents a leading cause of sudden cardiac death (SCD). The aim of this study was to assess the presence of an underlying electroanatomical arrhythmogenic substrate in high-risk LQTS patients. METHODS AND RESULTS: The present study enrolled 11 consecutive LQTS patients who had experienced frequent implantable cardioverter-defibrillator (ICD discharges triggered by ventricular fibrillation (VF). We acquired electroanatomical biventricular maps of both endo and epicardial regions for all patients and analyzed electrograms sampled from several myocardial regions. Abnormal electrical activities were targeted and eliminated by the means of radiofrequency catheter ablation. VF episodes caused a median of four ICD discharges in eleven patients (6 male, 54.5%; mean age 44.0 ± 7.8 years, range 22-53) prior to our mapping and ablation procedures. The average QTc interval was 500.0 ± 30.2 ms. Endo-epicardial biventricular maps displayed abnormally fragmented, low-voltage (0.9 ± 0.2 mV) and prolonged electrograms (89.9 ± 24.1 ms) exclusively localized in the right ventricular epicardium. We found electrical abnormalities extending over a mean epicardial area of 15.7 ± 3.1 cm2. Catheter ablation of the abnormal epicardial area completely suppressed malignant arrhythmias over a mean 12 months of follow-up (median VF episodes before vs. after ablation, 4 vs. 0; P = 0.003). After the procedure, the QTc interval measured in a 12-lead ECG analysis shortened to a mean of 461.8 ± 23.6 ms (P = 0.004). CONCLUSION: This study reveals that, among high-risk LQTS patients, regions localized in the epicardium of the right ventricle harbour structural electrophysiological abnormalities. Elimination of these abnormal electrical activities successfully prevented malignant ventricular arrhythmia recurrences.

High-risk Brugada syndrome: factors associated with arrhythmia recurrence and benefits of epicardial ablation in addition to implantable cardioverter defibrillator implantation.

AIMS: This study aims to evaluate the prognostic impact of the arrhythmogenic substrate size in symptomatic Brugada syndrome (BrS) as well as to validate the long-term safety and effectiveness of epicardial radiofrequency ablation (RFA) compared with no-RFA group. METHODS AND RESULTS: In this prospective investigational long-term registry study, 257 selected symptomatic BrS patients with implantable cardioverter defibrillator (ICD) implantation were included. Among them, 206 patients underwent epicardial RFA and were monitored for over 5 years post-ablation (RFA group), while 51 patients received only ICD implantation declining RFA. Primary endpoints included risk factors for ventricular fibrillation (VF) events pre-ablation and freedom from VF events post-ablation. In the RFA group, BrS substrates were identified in the epicardial surface of the right ventricle. During the pre-RFA follow-up period (median 27 months), VF episodes and VF storms were experienced by 53 patients. Independent risk factors included substrate size [hazard ratio (HR), 1.13; 95% confidence interval (CI), 1.08-1.18; P < 0.001], aborted cardiac arrest (HR, 2.98; 95% CI, 1.68-5.28; P < 0.001), and SCN5A variants (HR, 2.22; 95% CI, 1.15-4.27; P = 0.017). In the post-RFA follow-up (median 40 months), the RFA group demonstrated superior outcomes compared with no-RFA (P < 0.001) without major procedure-related complications. CONCLUSION: Our study underscores the role of BrS substrate extent as a crucial prognostic factor for recurrent VF and validates the safety and efficacy of RFA when compared with a no-RFA group. Our findings highlight the importance of ajmaline in guiding epicardial mapping/ablation in symptomatic BrS patients, laying the groundwork for further exploration of non-invasive methods to guide informed clinical decision-making.

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.

Unravelling Novel SCN5A Mutations Linked to Brugada Syndrome: Functional, Structural, and Genetic Insights.

Brugada Syndrome (BrS) is a rare inherited cardiac arrhythmia causing potentially fatal ventricular tachycardia or fibrillation, mainly occurring during rest or sleep in young individuals without heart structural issues. It increases the risk of sudden cardiac death, and its characteristic feature is an abnormal ST segment elevation on the ECG. While BrS has diverse genetic origins, a subset of cases can be conducted to mutations in the SCN5A gene, which encodes for the Nav1.5 sodium channel. Our study focused on three novel SCN5A mutations (p.A344S, p.N347K, and p.D349N) found in unrelated BrS families. Using patch clamp experiments, we found that these mutations disrupted sodium currents: p.A344S reduced current density, while p.N347K and p.D349N completely abolished it, leading to altered voltage dependence and inactivation kinetics when co-expressed with normal channels. We also explored the effects of mexiletine treatment, which can modulate ion channel function. Interestingly, the p.N347K and p.D349N mutations responded well to the treatment, rescuing the current density, while p.A344S showed a limited response. Structural analysis revealed these mutations were positioned in key regions of the channel, impacting its stability and function. This research deepens our understanding of BrS by uncovering the complex relationship between genetic mutations, ion channel behavior, and potential therapeutic interventions.

Brugada syndrome genetics is associated with phenotype severity.

AIMS: Brugada syndrome (BrS) is associated with an increased risk of sudden cardiac death due to ventricular tachycardia/fibrillation (VT/VF) in young, otherwise healthy individuals. Despite SCN5A being the most commonly known mutated gene to date, the genotype-phenotype relationship is poorly understood and remains uncertain. This study aimed to elucidate the genotype-phenotype correlation in BrS. METHODS AND RESULTS: Brugada syndrome probands deemed at high risk of future arrhythmic events underwent genetic testing and phenotype characterization by the means of epicardial arrhythmogenic substrate (AS) mapping, and were divided into two groups according to the presence or absence of SCN5A mutation. Two-hundred probands (160 males, 80%; mean age 42.6 ± 12.2 years) were included in this study. Patients harbouring SCN5A mutations exhibited a spontaneous type 1 pattern and experienced aborted cardiac arrest or spontaneous VT/VF more frequently than the other subjects. SCN5A-positive patients exhibited a larger epicardial AS area, more prolonged electrograms and more frequently observed non-invasive late potentials. The presence of an SCN5A mutation explained >26% of the variation in the epicardial AS area and was the strongest predictor of a large epicardial area. CONCLUSION: In BrS, the genetic background is the main determinant for the extent of the electrophysiological abnormalities. SCN5A mutation carriers exhibit more pronounced epicardial electrical abnormalities and a more aggressive clinical presentation. These results contribute to the understanding of the genetic determinants of the BrS phenotypic expression and provide possible explanations for the varying degrees of disease expression.

Alterations of the Sialylation Machinery in Brugada Syndrome.

Brugada Syndrome (BrS) is an inherited arrhythmogenic disorder with an increased risk of sudden cardiac death. Recent evidence suggests that BrS should be considered as an oligogenic or polygenic condition. Mutations in genes associated with BrS are found in about one-third of patients and they mainly disrupt the cardiac sodium channel NaV1.5, which is considered the main cause of the disease. However, voltage-gated channel's activity could be impacted by post-translational modifications such as sialylation, but their role in BrS remains unknown. Thus, we analyzed high risk BrS patients (n = 42) and healthy controls (n = 42) to assess an involvement of sialylation in BrS. Significant alterations in gene expression and protein sialylation were detected in Peripheral Blood Mononuclear Cells (PBMCs) from BrS patients. These changes were significantly associated with the phenotypic expression of the disease, as the size of the arrhythmogenic substrate and the duration of epicardial electrical abnormalities. Moreover, protein desialylation caused a reduction in the sodium current in an in vitro NaV1.5-overexpressing model. Dysregulation of the sialylation machinery provides definitive evidence that BrS affects extracardiac tissues, suggesting an underlying cause of the disease. Moreover, detection of these changes at the systemic level and their correlation with the clinical phenotype hint at the existence of a biomarker signature for BrS.

Role of sialidase Neu3 and ganglioside GM3 in cardiac fibroblasts activation.

Cardiac fibrosis is a key physiological response to cardiac tissue injury to protect the heart from wall rupture. However, its progression increases heart stiffness, eventually causing a decrease in heart contractility. Unfortunately, to date, no efficient antifibrotic therapies are available to the clinic. This is primarily due to the complexity of the process, which involves several cell types and signaling pathways. For instance, the transforming growth factor beta (TGF-ß) signaling pathway has been recognized to be vital for myofibroblasts activation and fibrosis progression. In this context, complex sphingolipids, such as ganglioside GM3, have been shown to be directly involved in TGF-ß receptor 1 (TGF-R1) activation. In this work, we report that an induced up-regulation of sialidase Neu3, a glycohydrolytic enzyme involved in ganglioside cell homeostasis, can significantly reduce cardiac fibrosis in primary cultures of human cardiac fibroblasts by inhibiting the TGF-ß signaling pathway, ultimately decreasing collagen I deposition. These results support the notion that modulating ganglioside GM3 cell content could represent a novel therapeutic approach for cardiac fibrosis, warranting for further investigations.

Clinical Considerations for a Family with Dilated Cardiomyopathy, Sudden Cardiac Death, and a Novel TTN Frameshift Mutation.

Dilated cardiomyopathy (DCM) is the leading indication for heart transplantation. TTN gene truncating mutations account for about 25% of familial DCM cases and for 18% of sporadic DCM cases. The clinical relevance of specific variants in TTN has been difficult to determine because of the sheer size of the protein for which TTN encodes, as well as existing extensive genetic variation. Clinicians should communicate novel clinically-relevant variants and genotype-phenotype associations, so that animal studies evaluating the molecular mechanisms are always conducted with a focus on clinical significance. In the present study, we report for the first time the novel truncating heterozygous variant NM_001256850.1:c.72777_72783del (p.Phe24259Leufs*51) in the TTN gene and its association with DCM in a family with sudden death. This variant occurs in the A-band region of the sarcomere, in a known mutational hotspot of the gene. Truncating titin variants that occur in this region are the most common cause of DCM and have been rarely reported in asymptomatic individuals, differently from other pathogenic TTN gene variants. Further studies are warranted to better understand this particular clinically-relevant variant.

Novel SCN5A p.Val1667Asp Missense Variant Segregation and Characterization in a Family with Severe Brugada Syndrome and Multiple Sudden Deaths.

Genetic testing in Brugada syndrome (BrS) is still not considered to be useful for clinical management of patients in the majority of cases, due to the current lack of understanding about the effect of specific variants. Additionally, family history of sudden death is generally not considered useful for arrhythmic risk stratification. We sought to demonstrate the usefulness of genetic testing and family history in diagnosis and risk stratification. The family history was collected for a proband who presented with a personal history of aborted cardiac arrest and in whom a novel variant in the SCN5A gene was found. Living family members underwent ajmaline testing, electrophysiological study, and genetic testing to determine genotype-phenotype segregation, if any. Patch-clamp experiments on transfected human embryonic kidney 293 cells enabled the functional characterization of the SCN5A novel variant in vitro. In this study, we provide crucial human data on the novel heterozygous variant NM_198056.2:c.5000T>A (p.Val1667Asp) in the SCN5A gene, and demonstrate its segregation with a severe form of BrS and multiple sudden deaths. Functional data revealed a loss of function of the protein affected by the variant. These results provide the first disease association with this variant and demonstrate the usefulness of genetic testing for diagnosis and risk stratification in certain patients. This study also demonstrates the usefulness of collecting the family history, which can assist in understanding the severity of the disease in certain situations and confirm the importance of the functional studies to distinguish between pathogenic mutations and harmless genetic variants.

The omics of channelopathies and cardiomyopathies: what we know and how they are useful.

Sudden cardiac death results from arrhythmias commonly caused by channelopathies and cardiomyopathies, often due to several genetic factors. An emerging concept is that these disease states may in fact overlap, with variants in traditionally classified 'cardiomyopathy genes' resulting in 'channelopathies phenotypes'. Another important concept is the influence of both genetic and non-genetic factors in disease expression, leading to the utilization of systems biology approaches, such as genomics/epigenomics, transcriptomics, proteomics, metabolomics, lipidomics, and glycomics, to understand the disease severity and progression and to determine the prognosis and the best course of treatment. In fact, our group has discovered significant differences in metabolites, proteins, and lipids between controls and Brugada syndrome patients. Omics approaches are useful in overcoming the dogma that both channelopathies and cardiomyopathies exist as Mendelian disorders (caused by a mutation in a single gene). This shift in understanding could lead to new diagnostic and therapeutic approaches.

Right ventricular electromechanical abnormalities in Brugada syndrome: is this a cardiomyopathy?

Brugada syndrome (BrS) has been often described as a purely electrical disease. However, current dogma surrounding this concept has shifted to accept that BrS is associated with structural abnormalities. Brugada syndrome is now associated with epicardial surface and interstitial fibrosis, reduced gap junction expression, increased collagen, and reduced contractility. The ventricular arrhythmias observed in BrS have been linked to an arrhythmogenic substrate (AS) located rather consistently in the right ventricular outflow tract, sparking much debate as to the significance of this anatomical position. The size of the AS is dynamic and can be altered due to a number of factors. A larger AS is associated with reduced contractility, and this impaired mechanical function may be responsible for syncopal episodes in BrS patients in the absence of arrhythmic events. While BrS is generally regarded as a channelopathy, recent studies have now identified also mutations in genes encoding for sarcomeric proteins to be associated with BrS. Future studies should evaluate electromechanical coupling in BrS, including calcium handling and sarcomeric alterations, and evaluate whether BrS should be classified as a cardiomyopathy.

Brugada Syndrome: Oligogenic or Mendelian Disease?

Brugada syndrome (BrS) is diagnosed by a coved-type ST-segment elevation in the right precordial leads on the electrocardiogram (ECG), and it is associated with an increased risk of sudden cardiac death (SCD) compared to the general population. Although BrS is considered a genetic disease, its molecular mechanism remains elusive in about 70-85% of clinically-confirmed cases. Variants occurring in at least 26 different genes have been previously considered causative, although the causative effect of all but the SCN5A gene has been recently challenged, due to the lack of systematic, evidence-based evaluations, such as a variant's frequency among the general population, family segregation analyses, and functional studies. Also, variants within a particular gene can be associated with an array of different phenotypes, even within the same family, preventing a clear genotype-phenotype correlation. Moreover, an emerging concept is that a single mutation may not be enough to cause the BrS phenotype, due to the increasing number of common variants now thought to be clinically relevant. Thus, not only the complete list of genes causative of the BrS phenotype remains to be determined, but also the interplay between rare and common multiple variants. This is particularly true for some common polymorphisms whose roles have been recently re-evaluated by outstanding works, including considering for the first time ever a polygenic risk score derived from the heterozygous state for both common and rare variants. The more common a certain variant is, the less impact this variant might have on heart function. We are aware that further studies are warranted to validate a polygenic risk score, because there is no mutated gene that connects all, or even a majority, of BrS cases. For the same reason, it is currently impossible to create animal and cell line genetic models that represent all BrS cases, which would enable the expansion of studies of this syndrome. Thus, the best model at this point is the human patient population. Further studies should first aim to uncover genetic variants within individuals, as well as to collect family segregation data to identify potential genetic causes of BrS.

Correlative Study on Impaired Prostaglandin E2 Regulation in Epicardial Adipose Tissue and its Role in Maladaptive Cardiac Remodeling via EPAC2 and ST2 Signaling in Overweight Cardiovascular Disease Subjects.

There is recent evidence that the dysfunctional responses of a peculiar visceral fat deposit known as epicardial adipose tissue (EAT) can directly promote cardiac enlargement in the case of obesity. Here, we observed a newer molecular pattern associated with LV dysfunction mediated by prostaglandin E2 (PGE2) deregulation in EAT in a cardiovascular disease (CVD) population. A series of 33 overweight CVD males were enrolled and their EAT thickness, LV mass, and volumes were measured by echocardiography. Blood, plasma, EAT, and SAT biopsies were collected for molecular and proteomic assays. Our data show that PGE2 biosynthetic enzyme (PTGES-2) correlates with echocardiographic parameters of LV enlargement: LV diameters, LV end diastolic volume, and LV masses. Moreover, PTGES-2 is directly associated with EPAC2 gene (r = 0.70, p < 0.0001), known as a molecular inducer of ST2/IL-33 mediators involved in maladaptive heart remodelling. Furthermore, PGE2 receptor 3 (PTEGER3) results are downregulated and its expression is inversely associated with ST2/IL-33 expression. Contrarily, PGE2 receptor 4 (PTGER4) is upregulated in EAT and directly correlates with ST2 molecular expression. Our data suggest that excessive body fatness can shift the EAT transcriptome to a pro-tissue remodelling profile, may be driven by PGE2 deregulation, with consequent promotion of EPAC2 and ST2 signalling.

Novel SCN5A p.V1429M Variant Segregation in a Family with Brugada Syndrome.

Brugada syndrome (BrS) is diagnosed by the presence of an elevated ST-segment and can result in sudden cardiac death. The most commonly found mutated gene is SCN5A, which some argue is the only gene that has been definitively confirmed to cause BrS, while the potential causative effect of other genes is still under debate. While the issue of BrS genetics is currently a hot topic, current knowledge is not able to result in molecular confirmation of over half of BrS cases. Therefore, it is difficult to develop research models with wide potential. Instead, the clinical genetics first need to be better understood. In this study, we provide crucial human data on the novel heterozygous variant NM_198056.2:c.4285G>A (p.Val1429Met) in the SCN5A gene, and demonstrate its segregation with BrS, suggesting a pathogenic effect. These results provide the first disease association with this variant and are crucial clinical data to communicate to basic scientists, who could perform functional studies to better understand the molecular effects of this clinically-relevant variant in BrS.

Non-invasive assessment of the arrhythmogenic substrate in Brugada syndrome using signal-averaged electrocardiogram: clinical implications from a prospective clinical trial.

AIMS: Brugada syndrome (BrS) represents a major cause of sudden cardiac death in young individuals. The risk stratification to forecast future life-threatening events is still controversial. Non-invasive assessment of late potentials (LPs) has been proposed as a risk stratification tool. However, their nature in BrS is still undetermined. The purpose of this study is to assess the electrophysiological determinants of non-invasive LPs. METHODS AND RESULTS: Two hundred and fifty consecutive patients with (Group 1, n = 96) and without (Group 2, n = 154) BrS-related symptoms were prospectively enrolled in the registry. Signal-averaged electrocardiogram (SAECG) was performed in all subjects before undergoing epicardial mapping. Group 1 patients exhibited larger arrhythmogenic substrates (AS; 5.8 ± 2.8 vs. 2.6 ± 2.1 cm2, P < 0.001) with more delayed potentials (220.4 ± 46.0 vs. 186.7 ± 42.3 ms, P < 0.001). Late potentials were present in 82/96 (85.4%) Group 1 and in 31/154 (20.1%) Group 2 individuals (P < 0.001). Patients exhibiting LPs had more frequently a spontaneous Type 1 pattern (30.1% vs. 10.9%, P < 0.001), SCN5A mutation (34.5% vs. 21.2%, P = 0.02), and exhibited a larger AS with longer potentials (5.8 ± 2.7 vs. 2.2 ± 1.7 cm2; 231.2 ± 37.3 vs. 213.8 ± 39.0 ms; P < 0.001, respectively). Arrhythmogenic substrate dimension was the strongest predictor of the presence of LPs (odds ratio 1.9; P < 0.001). An AS area of at least 3.5 cm2 identified patients with LPs (area under the curve 0.88, 95% confidence interval 0.843-0.931; P < 0.001) with a sensitivity of 86%, specificity 88%, positive predictive value 85%, and negative predictive value 89%. CONCLUSION: The results of this study support the role of the epicardial AS as an electrophysiological determinant of non-invasive LPs, which may serve as a tool in the non-invasive assessment of the BrS substrate, as SAECG-LPs could be considered an expression of the abnormal epicardial electrical activity.ClinicalTrials.gov number (NCT02641431; NCT03106701).

Comparable clinical characteristics in Brugada syndrome patients harboring SCN5A or novel SCN10A variants.

AIMS: The Brugada syndrome (BrS) is an inherited disease associated with an increased risk of sudden cardiac death. Often, the genetic cause remains undetected. Perhaps due at least in part because the NaV1.8 protein is expressed more in both the central and peripheral nervous systems than in the heart, the SCN10A gene is not included in diagnostic arrhythmia/sudden death panels in the vast majority of cardiogenetics centres. METHODS AND RESULTS: Clinical characteristics were assessed in patients harboring either SCN5A or novel SCN10A variants. Genetic testing was performed using Next Generation Sequencing on genomic DNA. Clinical characteristics, including the arrhythmogenic substrate, in BrS patients harboring novel SCN10A variants and SCN5A variants are comparable. Clinical characteristics, including gender, age, personal history of cardiac arrest/syncope, spontaneous BrS electrocardiogram pattern, family history of sudden death, and arrhythmic substrate are not significantly different between probands harboring SCN10A or SCN5A variants. CONCLUSION: Future studies are warranted to further characterize the role of these specific SCN10A variants.

Novel JAG1 Deletion Variant in Patient with Atypical Alagille Syndrome.

Alagille syndrome (AGS) is an autosomal-dominant disorder characterized by various degrees of abnormalities in the liver, heart, eyes, vertebrae, kidneys, face, vasculature, skeleton, and pancreas. This case report describes a newborn child exhibiting a congenital neural tube defect and peculiar craniofacial appearance characterized by a prominent forehead, deep-set eyes, bulbous nasal tip, and subtle upper lip. Just a few hours after birth, congenital heart disease was suspected for cyanosis and confirmed by heart evaluation. In particular, echocardiography indicated pulmonary atresia with ventricular septal defect with severe hypoplasia of the pulmonary branches (1.5 mm), large patent ductus arteriosus and several major aortopulmonary collateral arteries. Due to the association of peculiar craniofacial appearance and congenital heart disease, a form of Alagille syndrome was suspected. In addition, on the fifth day after birth, the patient developed jaundice, had acholic stools, and high levels of conjugated bilirubin and gamma-glutamyltransferase (GGT) were detected in the blood. Genetic testing revealed the novel variant c.802del in a single copy of the JAG1 gene. No variants in the NOTCH2 gene were detected. To the best of our knowledge, this is the first clinical description of a congenital neural tube defect in a molecularly confirmed Alagille patient. This work demonstrates a novel pathogenic heterozygous JAG1 mutation is associated with an atypical form of Alagille syndrome, suggesting an increased risk for neural tube defects compared to other Alagille patients.

Genotype-Phenotype Correlation in a Family with Brugada Syndrome Harboring the Novel p.Gln371* Nonsense Variant in the SCN5A Gene.

Brugada syndrome (BrS) is marked by coved ST-segment elevation and increased risk of sudden cardiac death. The genetics of this syndrome are elusive in over half of the cases. Variants in the SCN5A gene are the single most common known genetic unifier, accounting for about a third of cases. Research models, such as animal models and cell lines, are limited. In the present study, we report the novel NM_198056.2:c.1111C>T (p.Gln371*) heterozygous variant in the SCN5A gene, as well as its segregation with BrS in a large family. The results herein suggest a pathogenic effect of this variant. Functional studies are certainly warranted to characterize the molecular effects of this variant.