Publications by authors named "Connie Bezzina"

To broaden our understanding of bradyarrhythmias and conduction disease, we performed common variant genome-wide association analyses in up to 1.3 million individuals and rare variant burden testing in 460,000 individuals for sinus node dysfunction (SND), distal conduction disease (DCD) and pacemaker (PM) implantation. We identified 13, 31 and 21 common variant loci for SND, DCD and PM, respectively.

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Background: Congenital long QT syndrome (LQTS) is characterized by delayed ventricular repolarization, predisposing to potentially lethal ventricular arrhythmias. The variability in disease severity among patients remains largely unexplored, underscoring the limitations of current risk stratification methods.

Objective: We aimed to evaluate the potential utility of electrocardiographic markers from the exercise stress test (EST) in identifying patients with high-risk LQTS.

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  • The study focused on identifying imaging biomarkers for pre-clinical cardiomyopathy in healthy people with genetic variants linked to hypertrophic cardiomyopathy (HCM) or dilated cardiomyopathy (DCM).
  • Out of 40,169 participants, 13 cardiac magnetic resonance (CMR) measurements were found to be linked to atrial fibrillation (AF) and 15 with heart failure (HF), with specific measurements correlating differently with HCM and DCM genetic risk.
  • The findings suggest that certain CMR measurements, particularly from the right side of the heart, can indicate early changes in heart function in individuals with HCM genetic variants, while left ventricular measures relate to DCM genetic risks
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  • * A large study involving nearly 10,000 DCM cases and close to a million controls identified 70 significant genetic locations linked to the disease, revealing the importance of heart muscle cells in its development.
  • * The research also indicates that factors like higher body weight and blood pressure may contribute to DCM, and genetic risk scores can help predict the condition across different populations.
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  • Sudden cardiac death significantly impacts the life expectancy of individuals with schizophrenia, possibly linked to arrhythmic disorders, although the exact relationship remains unclear.
  • The study aimed to explore genetic connections and possible causal influences between schizophrenia and various heart-related conditions, utilizing extensive genetic data from large-scale studies.
  • Findings revealed minimal global genetic correlation, but specific genetic regions showed strong links, suggesting that schizophrenia risk may increase the likelihood of developing certain arrhythmias like Brugada syndrome and affect heart rate during activities.
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Background: The long-term prognosis of patients with a loss-of-function variant in the cardiac sodium channel gene SCN5A is unknown.

Objective: This study aimed to evaluate the long-term arrhythmic risk in patients with an SCN5A loss-of-function variant to identify predictors of arrhythmic events.

Methods: Probands and family members with (likely) pathogenic SCN5A loss-of-function variants were retrospectively included.

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Background: Altered metabolism plays a role in the pathophysiology of cardiac diseases, such as atrial fibrillation (AF) and heart failure (HF). We aimed to identify novel plasma metabolites and proteins associating with cardiac disease.

Methods: Mendelian randomisation (MR) was used to assess the association of 174 metabolites measured in up to 86,507 participants with AF, HF, dilated cardiomyopathy (DCM), and non-ischemic cardiomyopathy (NICM).

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Background: Congenital heart disease (CHD) is the most common congenital anomaly. Almost 90% of isolated cases have an unexplained genetic etiology after clinical testing. Non-canonical splice variants that disrupt mRNA splicing through the loss or creation of exon boundaries are not routinely captured and/or evaluated by standard clinical genetic tests.

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  • Brugada syndrome (BrS) is a hereditary cardiac disorder linked to sudden death in young adults, particularly prevalent in Southeast Asia, with certain genetic variants associated with the condition.
  • Researchers conducted genome sequencing on individuals with BrS and matched controls in Thailand to find rare noncoding variants that are more common in BrS patients.
  • A specific rare variant was identified that disrupts a transcription factor binding site, causing reduced gene expression and reduced sodium current in heart cells, contributing to the high prevalence of BrS in the region and identifying at-risk individuals.
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  • - The study examines how secondary genetic variants can influence the clinical features of individuals with primary disease-causing variants, suggesting that these modifiers play a significant role in disease expression.
  • - Specifically focusing on the 16p12.1 deletion, researchers identified various rare and common variants that predisposed individuals to specific developmental issues, such as neurological defects and microcephaly.
  • - By analyzing data from different cohorts, the findings indicate that the effects of primary and secondary variants on phenotype vary depending on the specific primary variant involved, highlighting the need for personalized approaches in treatment.
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  • The study aims to investigate the genetic factors associated with accessory atrioventricular pathways (APs) and related heart rhythm disorders using a genome-wide association study (GWAS).
  • It involved analyzing genetic data from over 1,200,000 control individuals and 2,310 individuals with APs from multiple countries and various health databases.
  • Key findings revealed three significant genetic variants linked to APs, particularly in specific genes (CCDC141 and SCN10A), with implications for understanding conditions like paroxysmal supraventricular tachycardia (PSVT).
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  • Large-scale sequencing has opened up new ways to study rare genetic variations and their impact on human traits across diverse populations.
  • Researchers analyzed data from three major biobanks, including the All of Us program, to perform gene-based testing for 601 diseases in nearly 750,000 individuals, revealing 363 significant genetic associations linked to various diseases.
  • The findings emphasized the importance of including diverse ancestries in genetic research, showcasing how certain genes like UBR3 and YLPM1 are associated with cardiovascular and psychiatric conditions, and suggested that effects of rare variants are consistent across different ancestry groups.
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  • * The 2023 ACC/AHA guidelines recommend genetic testing for AF patients aged 45 or younger to enhance personalized care and prognosis by identifying specific genetic defects.
  • * Challenges in genetic testing for AF include interpreting uncertain results, financial and insurance barriers, and the need for improved training and standardization in testing procedures.
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  • * A review of 391 papers led to a detailed analysis of 277 MR studies focused on arrhythmia and cardiovascular traits, identifying several risk factors for AF, including high systolic blood pressure and elevated cardiac troponin I levels.
  • * As genetic data becomes more available, the significance of MR increases, and combining it with other research methods can strengthen the reliability of conclusions drawn from these studies.
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encodes for the Popeye domain-containing protein 2 which has an important role in cardiac pacemaking and conduction, due in part to its cAMP-dependent binding and regulation of TREK-1 potassium channels. Loss of in mice results in sinus pauses and bradycardia and morpholino knockdown of zebrafish results in atrioventricular (AV) block. We identified bi-allelic variants in in 4 families that presented with a phenotypic spectrum consisting of sinus node dysfunction, AV conduction defects and hypertrophic cardiomyopathy.

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  • The study investigates how genetic background and age affect the severity of heart disease in a mouse model with SCN5A mutations, specifically focusing on the Scn5a1798insD/+ mice.
  • Results showed that aged mutant mice, particularly those from the 129P2 strain, exhibited more severe electrical dysfunctions and structural changes compared to the FVB/N strain, including prolonged conduction times and increased risk of arrhythmias.
  • The findings suggest that both age and genetic background are important factors in the expression of cardiac disease in SCN5A mutation patients, highlighting the need for tailored approaches in assessing and managing these conditions.
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Background And Aims: Brugada syndrome (BrS) is an inherited arrhythmia with a higher disease prevalence and more lethal arrhythmic events in Asians than in Europeans. Genome-wide association studies (GWAS) have revealed its polygenic architecture mainly in European populations. The aim of this study was to identify novel BrS-associated loci and to compare allelic effects across ancestries.

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Long QT syndrome (LQTS), caused by the dysfunction of cardiac ion channels, increases the risk of sudden death in otherwise healthy young people. For many variants in LQTS genes, there is insufficient evidence to make a definitive genetic diagnosis. We have established a robust functional patch-clamp assay to facilitate classification of missense variants in KCNH2, one of the key LQTS genes.

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  • Brugada syndrome, primarily caused by loss-of-function variants, has only about 20% of cases explained by known genetic factors; recent studies point to the role of microtubule dynamics in the syndrome.
  • Researchers used CRISPR/Cas9 to create a knockout zebrafish model and conducted various experiments like voltage mapping, ECG, and immunocytochemistry to evaluate cardiac function.
  • Findings showed that knockout hearts had impaired electrical activity and disorganized cell junctions, with a notable improvement when adjusting microtubule dynamics through targeted interventions.
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Background: Hypertrophic cardiomyopathy (HCM) is an important cause of sudden cardiac death associated with heterogeneous phenotypes, but there is no systematic framework for classifying morphology or assessing associated risks. Here, we quantitatively survey genotype-phenotype associations in HCM to derive a data-driven taxonomy of disease expression.

Methods: We enrolled 436 patients with HCM (median age, 60 years; 28.

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  • Inherited forms of arrhythmogenic and dilated cardiomyopathy (ACM and DCM) exhibit varying symptoms and risk levels depending on age, with calcium regulation being a key factor in these heart conditions.
  • A specific genetic change, c.286T>G p.(Ser96Ala), linked to serious arrhythmias in DCM patients, was examined for its impact on different cardiomyopathy groups, including those with a known pathogenic variant.
  • The study found no significant differences in allele frequency between the general population and those with cardiomyopathy, indicating the p.(Ser96Ala) polymorphism does not modify disease severity or risk, suggesting the need for further research into reliable genetic markers for these heart conditions
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