Publications by authors named "Connie R Bezzina"

166 Publications

Biallelic loss-of-function variants in PLD1 cause congenital right-sided cardiac valve defects and neonatal cardiomyopathy.

J Clin Invest 2021 03;131(5)

Amsterdam UMC, University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences.

Congenital heart disease is the most common type of birth defect, accounting for one-third of all congenital anomalies. Using whole-exome sequencing of 2718 patients with congenital heart disease and a search in GeneMatcher, we identified 30 patients from 21 unrelated families of different ancestries with biallelic phospholipase D1 (PLD1) variants who presented predominantly with congenital cardiac valve defects. We also associated recessive PLD1 variants with isolated neonatal cardiomyopathy. Furthermore, we established that p.I668F is a founder variant among Ashkenazi Jews (allele frequency of ~2%) and describe the phenotypic spectrum of PLD1-associated congenital heart defects. PLD1 missense variants were overrepresented in regions of the protein critical for catalytic activity, and, correspondingly, we observed a strong reduction in enzymatic activity for most of the mutant proteins in an enzymatic assay. Finally, we demonstrate that PLD1 inhibition decreased endothelial-mesenchymal transition, an established pivotal early step in valvulogenesis. In conclusion, our study provides a more detailed understanding of disease mechanisms and phenotypic expression associated with PLD1 loss of function.
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http://dx.doi.org/10.1172/JCI142148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919725PMC
March 2021

Electrophysiological Abnormalities in VLCAD Deficient hiPSC-Cardiomyocytes Do not Improve with Carnitine Supplementation.

Front Pharmacol 2020 12;11:616834. Epub 2021 Jan 12.

Laboratory Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam Gastroenterology and Metabolism, Amsterdam Cardiovascular Sciences, Amsterdam, Netherlands.

Patients with a deficiency in very long-chain acyl-CoA dehydrogenase (VLCAD), an enzyme that is involved in the mitochondrial beta-oxidation of long-chain fatty acids, are at risk for developing cardiac arrhythmias. In human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs), VLCAD deficiency (VLCADD) results in a series of abnormalities, including: 1) accumulation of long-chain acylcarnitines, 2) action potential shortening, 3) higher systolic and diastolic intracellular Ca concentrations, and 4) development of delayed afterdepolarizations. In the fatty acid oxidation process, carnitine is required for bidirectional transport of acyl groups across the mitochondrial membrane. Supplementation has been suggested as potential therapeutic approach in VLCADD, but its benefits are debated. Here, we studied the effects of carnitine supplementation on the long-chain acylcarnitine levels and performed electrophysiological analyses in VLCADD patient-derived hiPSC-CMs with a gene mutation (p.Val283Ala/p.Glu381del). Under standard culture conditions, VLCADD hiPSC-CMs showed high concentrations of long-chain acylcarnitines, short action potentials, and high delayed afterdepolarizations occurrence. Incubation of the hiPSC-CMs with 400 µM L-carnitine for 48 h led to increased long-chain acylcarnitine levels both in medium and cells. In addition, carnitine supplementation neither restored abnormal action potential parameters nor the increased occurrence of delayed afterdepolarizations in VLCADD hiPSC-CMs. We conclude that long-chain acylcarnitine accumulation and electrophysiological abnormalities in VLCADD hiPSC-CMs are not normalized by carnitine supplementation, indicating that this treatment is unlikely to be beneficial against cardiac arrhythmias in VLCADD patients.
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http://dx.doi.org/10.3389/fphar.2020.616834DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7883678PMC
January 2021

Systematic large-scale assessment of the genetic architecture of left ventricular noncompaction reveals diverse etiologies.

Genet Med 2021 Jan 26. Epub 2021 Jan 26.

Amsterdam UMC, University of Amsterdam, Department of Clinical and Experimental Cardiology, Heart Centre, Amsterdam, Netherlands.

Purpose: To characterize the genetic architecture of left ventricular noncompaction (LVNC) and investigate the extent to which it may represent a distinct pathology or a secondary phenotype associated with other cardiac diseases.

Methods: We performed rare variant association analysis with 840 LVNC cases and 125,748 gnomAD population controls, and compared results to similar analyses on dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM).

Results: We observed substantial genetic overlap indicating that LVNC often represents a phenotypic variation of DCM or HCM. In contrast, truncating variants in MYH7, ACTN2, and PRDM16 were uniquely associated with LVNC and may reflect a distinct LVNC etiology. In particular, MYH7 truncating variants (MYH7tv), generally considered nonpathogenic for cardiomyopathies, were 20-fold enriched in LVNC cases over controls. MYH7tv heterozygotes identified in the UK Biobank and healthy volunteer cohorts also displayed significantly greater noncompaction compared with matched controls. RYR2 exon deletions and HCN4 transmembrane variants were also enriched in LVNC, supporting prior reports of association with arrhythmogenic LVNC phenotypes.

Conclusion: LVNC is characterized by substantial genetic overlap with DCM/HCM but is also associated with distinct noncompaction and arrhythmia etiologies. These results will enable enhanced application of LVNC genetic testing and help to distinguish pathological from physiological noncompaction.
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http://dx.doi.org/10.1038/s41436-020-01049-xDOI Listing
January 2021

Common genetic variants and modifiable risk factors underpin hypertrophic cardiomyopathy susceptibility and expressivity.

Nat Genet 2021 02 25;53(2):135-142. Epub 2021 Jan 25.

Radcliffe Department of Medicine, Division of Cardiovascular Medicine, University of Oxford, Oxford, UK.

Hypertrophic cardiomyopathy (HCM) is a common, serious, genetic heart disorder. Rare pathogenic variants in sarcomere genes cause HCM, but with unexplained phenotypic heterogeneity. Moreover, most patients do not carry such variants. We report a genome-wide association study of 2,780 cases and 47,486 controls that identified 12 genome-wide-significant susceptibility loci for HCM. Single-nucleotide polymorphism heritability indicated a strong polygenic influence, especially for sarcomere-negative HCM (64% of cases; h = 0.34 ± 0.02). A genetic risk score showed substantial influence on the odds of HCM in a validation study, halving the odds in the lowest quintile and doubling them in the highest quintile, and also influenced phenotypic severity in sarcomere variant carriers. Mendelian randomization identified diastolic blood pressure (DBP) as a key modifiable risk factor for sarcomere-negative HCM, with a one standard deviation increase in DBP increasing the HCM risk fourfold. Common variants and modifiable risk factors have important roles in HCM that we suggest will be clinically actionable.
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http://dx.doi.org/10.1038/s41588-020-00764-0DOI Listing
February 2021

Shared genetic pathways contribute to risk of hypertrophic and dilated cardiomyopathies with opposite directions of effect.

Nat Genet 2021 02 25;53(2):128-134. Epub 2021 Jan 25.

Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, University of Amsterdam, Amsterdam UMC, Amsterdam, the Netherlands.

The heart muscle diseases hypertrophic (HCM) and dilated (DCM) cardiomyopathies are leading causes of sudden death and heart failure in young, otherwise healthy, individuals. We conducted genome-wide association studies and multi-trait analyses in HCM (1,733 cases), DCM (5,521 cases) and nine left ventricular (LV) traits (19,260 UK Biobank participants with structurally normal hearts). We identified 16 loci associated with HCM, 13 with DCM and 23 with LV traits. We show strong genetic correlations between LV traits and cardiomyopathies, with opposing effects in HCM and DCM. Two-sample Mendelian randomization supports a causal association linking increased LV contractility with HCM risk. A polygenic risk score explains a significant portion of phenotypic variability in carriers of HCM-causing rare variants. Our findings thus provide evidence that polygenic risk score may account for variability in Mendelian diseases. More broadly, we provide insights into how genetic pathways may lead to distinct disorders through opposing genetic effects.
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http://dx.doi.org/10.1038/s41588-020-00762-2DOI Listing
February 2021

Illuminating the path from genetics to clinical outcome in Brugada syndrome.

Eur Heart J 2021 Mar;42(11):1091-1093

Department of Experimental Cardiology, Amsterdam UMC, AMC Heart Center, Amsterdam, The Netherlands.

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http://dx.doi.org/10.1093/eurheartj/ehaa994DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7955964PMC
March 2021

Two siblings with early repolarization syndrome: clinical and genetic characterization by whole-exome sequencing.

Europace 2020 Dec 16. Epub 2020 Dec 16.

Department of Clinical and Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Heart Center, Amsterdam, The Netherlands.

Aims : The early repolarization syndrome (ERS) can cause ventricular fibrillation (VF) and sudden death in young, otherwise healthy individuals. There are limited data suggesting that ERS might be heritable. The aim of this study was to characterize the clinical phenotype and to identify a causal variant in an affected family using an exome-sequencing approach.

Methods And Results : Early repolarization syndrome was diagnosed according to the recently proposed Shanghai ERS Score. After sequencing of known ERS candidate genes, whole-exome sequencing (WES) was performed. The index patient (23 years, female) showed a dynamic inferolateral early repolarization (ER) pattern and electrical storm with intractable VF. Isoproterenol enabled successful termination of electrical storm with no recurrence on hydroquinidine therapy during 33 months of follow-up. The index patient's brother (25 years) had a persistent inferior ER pattern with malignant features and a history of syncope. Both parents were asymptomatic and showed no ER pattern. While there was no pathogenic variant in candidate genes, WES detected a novel missense variant affecting a highly conserved residue (p. H2245R) in the ANK3 gene encoding Ankyrin-G in the two siblings and the father.

Conclusion : We identified two siblings with a malignant ERS phenotype sharing a novel ANK3 variant. A potentially pathogenic role of the novel ANK3 variant is suggested by the direct interaction of Ankyrin-G with the cardiac sodium channel, however, more patients with ANK3 variants and ERS would be required to establish ANK3 as novel ERS susceptibility gene. Our study provides additional evidence that ERS might be a heritable condition.
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http://dx.doi.org/10.1093/europace/euaa357DOI Listing
December 2020

Mutation Type and a Genetic Risk Score Associate Variably With Brugada Syndrome Phenotype in Families.

Circ Genom Precis Med 2020 12 9;13(6):e002911. Epub 2020 Nov 9.

Molecular and Clinical Sciences Research Institute, St George's University of London, Cardiovascular Clinical Academic Group, St George's University Hospitals National Health Service (NHS) Foundation Trust, United Kingdom (Y.D.W., V.B., M.M., H.R., M.P., S.S., E.R.B.).

Background: Brugada syndrome (BrS) is characterized by the type 1 Brugada ECG pattern. Pathogenic rare variants in (mutations) are identified in 20% of BrS families in whom incomplete penetrance and genotype-negative phenotype-positive individuals are observed. E1784K- is the most common mutation identified. We determined the association of a BrS genetic risk score (BrS-GRS) and mutation type on BrS phenotype in BrS families with mutations.

Methods: Subjects with a spontaneous type 1 pattern or positive/negative drug challenge from cohorts harboring mutations were recruited from 16 centers (n=312). Single nucleotide polymorphisms previously associated with BrS at genome-wide significance were studied in both cohorts: rs11708996, rs10428132, and rs9388451. An additive linear genetic model for the BrS-GRS was assumed (6 single nucleotide polymorphism risk alleles).

Results: In the total population (n=312), BrS-GRS ≥4 risk alleles yielded an odds ratio of 4.15 for BrS phenotype ([95% CI, 1.45-11.85]; =0.0078). Among -positive individuals (n=258), BrS-GRS ≥4 risk alleles yielded an odds ratio of 2.35 ([95% CI, 0.89-6.22]; =0.0846). In -negative relatives (n=54), BrS-GRS ≥4 alleles yielded an odds ratio of 22.29 ([95% CI, 1.84-269.30]; =0.0146). Among E1784K- positive family members (n=79), hosting ≥4 risk alleles gave an odds ratio=5.12 ([95% CI, 1.93-13.62]; =0.0011).

Conclusions: Common genetic variation is associated with variable expressivity of BrS phenotype in families, explaining in part incomplete penetrance and genotype-negative phenotype-positive individuals. mutation genotype and a BrS-GRS associate with BrS phenotype, but the strength of association varies according to presence of a mutation and severity of loss of function.
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http://dx.doi.org/10.1161/CIRCGEN.120.002911DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7748043PMC
December 2020

Enhancing rare variant interpretation in inherited arrhythmias through quantitative analysis of consortium disease cohorts and population controls.

Authors:
Roddy Walsh Najim Lahrouchi Rafik Tadros Florence Kyndt Charlotte Glinge Pieter G Postema Ahmad S Amin Eline A Nannenberg James S Ware Nicola Whiffin Francesco Mazzarotto Doris Škorić-Milosavljević Christian Krijger Elena Arbelo Dominique Babuty Hector Barajas-Martinez Britt M Beckmann Stéphane Bézieau J Martijn Bos Jeroen Breckpot Oscar Campuzano Silvia Castelletti Candan Celen Sebastian Clauss Anniek Corveleyn Lia Crotti Federica Dagradi Carlo de Asmundis Isabelle Denjoy Sven Dittmann Patrick T Ellinor Cristina Gil Ortuño Carla Giustetto Jean-Baptiste Gourraud Daisuke Hazeki Minoru Horie Taisuke Ishikawa Hideki Itoh Yoshiaki Kaneko Jørgen K Kanters Hiroki Kimoto Maria-Christina Kotta Ingrid P C Krapels Masahiko Kurabayashi Julieta Lazarte Antoine Leenhardt Bart L Loeys Catarina Lundin Takeru Makiyama Jacques Mansourati Raphaël P Martins Andrea Mazzanti Stellan Mörner Carlo Napolitano Kimie Ohkubo Michael Papadakis Boris Rudic Maria Sabater Molina Frédéric Sacher Hatice Sahin Georgia Sarquella-Brugada Regina Sebastiano Sanjay Sharma Mary N Sheppard Keiko Shimamoto M Benjamin Shoemaker Birgit Stallmeyer Johannes Steinfurt Yuji Tanaka David J Tester Keisuke Usuda Paul A van der Zwaag Sonia Van Dooren Lut Van Laer Annika Winbo Bo G Winkel Kenichiro Yamagata Sven Zumhagen Paul G A Volders Steven A Lubitz Charles Antzelevitch Pyotr G Platonov Katja E Odening Dan M Roden Jason D Roberts Jonathan R Skinner Jacob Tfelt-Hansen Maarten P van den Berg Morten S Olesen Pier D Lambiase Martin Borggrefe Kenshi Hayashi Annika Rydberg Tadashi Nakajima Masao Yoshinaga Johan B Saenen Stefan Kääb Pedro Brugada Tomas Robyns Daniela F Giachino Michael J Ackerman Ramon Brugada Josep Brugada Juan R Gimeno Can Hasdemir Pascale Guicheney Silvia G Priori Eric Schulze-Bahr Naomasa Makita Peter J Schwartz Wataru Shimizu Takeshi Aiba Jean-Jacques Schott Richard Redon Seiko Ohno Vincent Probst Elijah R Behr Julien Barc Connie R Bezzina

Genet Med 2021 Jan 7;23(1):47-58. Epub 2020 Sep 7.

Department of Clinical and Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands.

Purpose: Stringent variant interpretation guidelines can lead to high rates of variants of uncertain significance (VUS) for genetically heterogeneous disease like long QT syndrome (LQTS) and Brugada syndrome (BrS). Quantitative and disease-specific customization of American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines can address this false negative rate.

Methods: We compared rare variant frequencies from 1847 LQTS (KCNQ1/KCNH2/SCN5A) and 3335 BrS (SCN5A) cases from the International LQTS/BrS Genetics Consortia to population-specific gnomAD data and developed disease-specific criteria for ACMG/AMP evidence classes-rarity (PM2/BS1 rules) and case enrichment of individual (PS4) and domain-specific (PM1) variants.

Results: Rare SCN5A variant prevalence differed between European (20.8%) and Japanese (8.9%) BrS patients (p = 5.7 × 10) and diagnosis with spontaneous (28.7%) versus induced (15.8%) Brugada type 1 electrocardiogram (ECG) (p = 1.3 × 10). Ion channel transmembrane regions and specific N-terminus (KCNH2) and C-terminus (KCNQ1/KCNH2) domains were characterized by high enrichment of case variants and >95% probability of pathogenicity. Applying the customized rules, 17.4% of European BrS and 74.8% of European LQTS cases had (likely) pathogenic variants, compared with estimated diagnostic yields (case excess over gnomAD) of 19.2%/82.1%, reducing VUS prevalence to close to background rare variant frequency.

Conclusion: Large case-control data sets enable quantitative implementation of ACMG/AMP guidelines and increased sensitivity for inherited arrhythmia genetic testing.
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http://dx.doi.org/10.1038/s41436-020-00946-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7790744PMC
January 2021

Functional modulation of atrio-ventricular conduction by enhanced late sodium current and calcium-dependent mechanisms in Scn5a1798insD/+ mice.

Europace 2020 10;22(10):1579-1589

Department of Clinical and Experimental Cardiology, Amsterdam UMC, Heart Center, Academic Medical Center, Room K2-104.2, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.

Aims: SCN5A mutations are associated with arrhythmia syndromes, including Brugada syndrome, long QT syndrome type 3 (LQT3), and cardiac conduction disease. Long QT syndrome type 3 patients display atrio-ventricular (AV) conduction slowing which may contribute to arrhythmogenesis. We here investigated the as yet unknown underlying mechanisms.

Methods And Results: We assessed electrophysiological and molecular alterations underlying AV-conduction abnormalities in mice carrying the Scn5a1798insD/+ mutation. Langendorff-perfused Scn5a1798insD/+ hearts showed prolonged AV-conduction compared to wild type (WT) without changes in atrial and His-ventricular (HV) conduction. The late sodium current (INa,L) inhibitor ranolazine (RAN) normalized AV-conduction in Scn5a1798insD/+ mice, likely by preventing the mutation-induced increase in intracellular sodium ([Na+]i) and calcium ([Ca2+]i) concentrations. Indeed, further enhancement of [Na+]i and [Ca2+]i by the Na+/K+-ATPase inhibitor ouabain caused excessive increase in AV-conduction time in Scn5a1798insD/+ hearts. Scn5a1798insD/+ mice from the 129P2 strain displayed more severe AV-conduction abnormalities than FVB/N-Scn5a1798insD/+ mice, in line with their larger mutation-induced INa,L. Transverse aortic constriction (TAC) caused excessive prolongation of AV-conduction in FVB/N-Scn5a1798insD/+ mice (while HV-intervals remained unchanged), which was prevented by chronic RAN treatment. Scn5a1798insD/+-TAC hearts showed decreased mRNA levels of conduction genes in the AV-nodal region, but no structural changes in the AV-node or His bundle. In Scn5a1798insD/+-TAC mice deficient for the transcription factor Nfatc2 (effector of the calcium-calcineurin pathway), AV-conduction and conduction gene expression were restored to WT levels.

Conclusions: Our findings indicate a detrimental role for enhanced INa,L and consequent calcium dysregulation on AV-conduction in Scn5a1798insD/+ mice, providing evidence for a functional mechanism underlying AV-conduction disturbances secondary to gain-of-function SCN5A mutations.
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http://dx.doi.org/10.1093/europace/euaa127DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7544532PMC
October 2020

Inherited cardiac arrhythmias.

Nat Rev Dis Primers 2020 07 16;6(1):58. Epub 2020 Jul 16.

European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-HEART), Bruxelles, Belgium.

The main inherited cardiac arrhythmias are long QT syndrome, short QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. These rare diseases are often the underlying cause of sudden cardiac death in young individuals and result from mutations in several genes encoding ion channels or proteins involved in their regulation. The genetic defects lead to alterations in the ionic currents that determine the morphology and duration of the cardiac action potential, and individuals with these disorders often present with syncope or a life-threatening arrhythmic episode. The diagnosis is based on clinical presentation and history, the characteristics of the electrocardiographic recording at rest and during exercise and genetic analyses. Management relies on pharmacological therapy, mostly β-adrenergic receptor blockers (specifically, propranolol and nadolol) and sodium and transient outward current blockers (such as quinidine), or surgical interventions, including left cardiac sympathetic denervation and implantation of a cardioverter-defibrillator. All these arrhythmias are potentially life-threatening and have substantial negative effects on the quality of life of patients. Future research should focus on the identification of genes associated with the diseases and other risk factors, improved risk stratification and, in particular for Brugada syndrome, effective therapies.
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http://dx.doi.org/10.1038/s41572-020-0188-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7935690PMC
July 2020

Common and rare susceptibility genetic variants predisposing to Brugada syndrome in Thailand.

Heart Rhythm 2020 12 30;17(12):2145-2153. Epub 2020 Jun 30.

Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Pacific Rim Electrophysiology Research Institute, Bumrungrad Hospital, Bangkok, Thailand.

Background: Mutations in SCN5A are rarely found in Thai patients with Brugada syndrome (BrS). Recent evidence suggested that common genetic variations may underlie BrS in a complex inheritance model.

Objective: The purpose of this study was to find common and rare/low-frequency genetic variants predisposing to BrS in persons in Thailand.

Methods: We conducted a genome-wide association study (GWAS) to explore the association of common variants in 154 Thai BrS cases and 432 controls. We sequenced SCN5A in 131 cases and 205 controls. Variants were classified according to current guidelines, and case-control association testing was performed for rare and low-frequency variants.

Results: Two loci were significantly associated with BrS. The first was near SCN5A/SCN10A (lead marker rs10428132; odds ratio [OR] 2.4; P = 3 × 10). Conditional analysis identified a novel independent signal in the same locus (rs6767797; OR 2.3; P = 2.7 × 10). The second locus was near HEY2 (lead marker rs3734634; OR 2.5; P = 7 × 10). Rare (minor allele frequency [MAF] <0.0001) coding variants in SCN5A were found in 8 of the 131 cases (6.1% in cases vs 2.0% in controls; P = .046; OR 3.3; 95% confident interval [CI] 1.0-11.1), but an enrichment of low-frequency (MAF<0.001 and >0.0001) variants also was observed in cases, with 1 variant (SCN5A: p.Arg965Cys) detected in 4.6% of Thai BrS patients vs 0.5% in controls (P = 0.015; OR 9.8; 95% CI 1.2-82.3).

Conclusion: The genetic basis of BrS in Thailand includes a wide spectrum of variant frequencies and effect sizes. As previously shown in European and Japanese populations, common variants near SCN5A and HEY2 are associated with BrS in the Thai population, confirming the transethnic transferability of these 2 major BrS loci.
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http://dx.doi.org/10.1016/j.hrthm.2020.06.027DOI Listing
December 2020

Transethnic Genome-Wide Association Study Provides Insights in the Genetic Architecture and Heritability of Long QT Syndrome.

Authors:
Najim Lahrouchi Rafik Tadros Lia Crotti Yuka Mizusawa Pieter G Postema Leander Beekman Roddy Walsh Kanae Hasegawa Julien Barc Marko Ernsting Kari L Turkowski Andrea Mazzanti Britt M Beckmann Keiko Shimamoto Ulla-Britt Diamant Yanushi D Wijeyeratne Yu Kucho Tomas Robyns Taisuke Ishikawa Elena Arbelo Michael Christiansen Annika Winbo Reza Jabbari Steven A Lubitz Johannes Steinfurt Boris Rudic Bart Loeys M Ben Shoemaker Peter E Weeke Ryan Pfeiffer Brianna Davies Antoine Andorin Nynke Hofman Federica Dagradi Matteo Pedrazzini David J Tester J Martijn Bos Georgia Sarquella-Brugada Óscar Campuzano Pyotr G Platonov Birgit Stallmeyer Sven Zumhagen Eline A Nannenberg Jan H Veldink Leonard H van den Berg Ammar Al-Chalabi Christopher E Shaw Pamela J Shaw Karen E Morrison Peter M Andersen Martina Müller-Nurasyid Daniele Cusi Cristina Barlassina Pilar Galan Mark Lathrop Markus Munter Thomas Werge Marta Ribasés Tin Aung Chiea C Khor Mineo Ozaki Peter Lichtner Thomas Meitinger J Peter van Tintelen Yvonne Hoedemaekers Isabelle Denjoy Antoine Leenhardt Carlo Napolitano Wataru Shimizu Jean-Jacques Schott Jean-Baptiste Gourraud Takeru Makiyama Seiko Ohno Hideki Itoh Andrew D Krahn Charles Antzelevitch Dan M Roden Johan Saenen Martin Borggrefe Katja E Odening Patrick T Ellinor Jacob Tfelt-Hansen Jonathan R Skinner Maarten P van den Berg Morten Salling Olesen Josep Brugada Ramón Brugada Naomasa Makita Jeroen Breckpot Masao Yoshinaga Elijah R Behr Annika Rydberg Takeshi Aiba Stefan Kääb Silvia G Priori Pascale Guicheney Hanno L Tan Christopher Newton-Cheh Michael J Ackerman Peter J Schwartz Eric Schulze-Bahr Vincent Probst Minoru Horie Arthur A Wilde Michael W T Tanck Connie R Bezzina

Circulation 2020 Jul 20;142(4):324-338. Epub 2020 May 20.

Amsterdam UMC, University of Amsterdam, Heart Center; Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, The Netherlands (N.L., R.T., Y.M., P.G.P., L.B., R.W., N.H., H.L.T., A.A.W., C.R.B.).

Background: Long QT syndrome (LQTS) is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. A causal rare genetic variant with large effect size is identified in up to 80% of probands (genotype positive) and cascade family screening shows incomplete penetrance of genetic variants. Furthermore, a proportion of cases meeting diagnostic criteria for LQTS remain genetically elusive despite genetic testing of established genes (genotype negative). These observations raise the possibility that common genetic variants with small effect size contribute to the clinical picture of LQTS. This study aimed to characterize and quantify the contribution of common genetic variation to LQTS disease susceptibility.

Methods: We conducted genome-wide association studies followed by transethnic meta-analysis in 1656 unrelated patients with LQTS of European or Japanese ancestry and 9890 controls to identify susceptibility single nucleotide polymorphisms. We estimated the common variant heritability of LQTS and tested the genetic correlation between LQTS susceptibility and other cardiac traits. Furthermore, we tested the aggregate effect of the 68 single nucleotide polymorphisms previously associated with the QT-interval in the general population using a polygenic risk score.

Results: Genome-wide association analysis identified 3 loci associated with LQTS at genome-wide statistical significance (<5×10) near , , and , and 1 missense variant in (p.Asp85Asn) at the suggestive threshold (<10). Heritability analyses showed that ≈15% of variance in overall LQTS susceptibility was attributable to common genetic variation ( 0.148; standard error 0.019). LQTS susceptibility showed a strong genome-wide genetic correlation with the QT-interval in the general population (r=0.40; =3.2×10). The polygenic risk score comprising common variants previously associated with the QT-interval in the general population was greater in LQTS cases compared with controls (<10-13), and it is notable that, among patients with LQTS, this polygenic risk score was greater in patients who were genotype negative compared with those who were genotype positive (<0.005).

Conclusions: This work establishes an important role for common genetic variation in susceptibility to LQTS. We demonstrate overlap between genetic control of the QT-interval in the general population and genetic factors contributing to LQTS susceptibility. Using polygenic risk score analyses aggregating common genetic variants that modulate the QT-interval in the general population, we provide evidence for a polygenic architecture in genotype negative LQTS.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.045956DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382531PMC
July 2020

Genome-wide association studies of cardiac electrical phenotypes.

Cardiovasc Res 2020 Jul;116(9):1620-1634

Department of Clinical and Experimental Cardiology, Amsterdam University Medical Center, University of Amsterdam, Heart Center, Amsterdam Cardiovascular Sciences, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.

The genetic basis of cardiac electrical phenotypes has in the last 25 years been the subject of intense investigation. While in the first years, such efforts were dominated by the study of familial arrhythmia syndromes, in recent years, large consortia of investigators have successfully pursued genome-wide association studies (GWAS) for the identification of single-nucleotide polymorphisms that govern inter-individual variability in electrocardiographic parameters in the general population. We here provide a review of GWAS conducted on cardiac electrical phenotypes in the last 14 years and discuss the implications of these discoveries for our understanding of the genetic basis of disease susceptibility and variability in disease severity. Furthermore, we review functional follow-up studies that have been conducted on GWAS loci associated with cardiac electrical phenotypes and highlight the challenges and opportunities offered by such studies.
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http://dx.doi.org/10.1093/cvr/cvaa144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7341169PMC
July 2020

When genetic burden reaches threshold.

Eur Heart J 2020 10;41(39):3849-3855

Department of Clinical and Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, Netherlands.

Rare cardiac genetic diseases have generally been considered to be broadly Mendelian in nature, with clinical genetic testing for these conditions predicated on the detection of a primary causative rare pathogenic variant that will enable cascade genetic screening in families. However, substantial variability in penetrance and disease severity among carriers of pathogenic variants, as well as the inability to detect rare Mendelian variants in considerable proportions of patients, indicates that more complex aetiologies are likely to underlie these diseases. Recent findings have suggested genetic variants across a range of population frequencies and effect sizes may combine, along with non-genetic factors, to determine whether the threshold for expression of disease is reached and the severity of the phenotype. The availability of increasingly large genetically characterized cohorts of patients with rare cardiac diseases is enabling the discovery of common genetic variation that may underlie both variable penetrance in Mendelian diseases and the genetic aetiology of apparently non-Mendelian rare cardiac conditions. It is likely that the genetic architecture of rare cardiac diseases will vary considerably between different conditions as well as between patients with similar phenotypes, ranging from near-Mendelian disease to models more akin to common, complex disease. Uncovering the broad range of genetic factors that predispose patients to rare cardiac diseases offers the promise of improved risk prediction and more focused clinical management in patients and their families.
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http://dx.doi.org/10.1093/eurheartj/ehaa269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599032PMC
October 2020

Electrophysiological Abnormalities in VLCAD Deficient hiPSC-Cardiomyocytes Can Be Improved by Lowering Accumulation of Fatty Acid Oxidation Intermediates.

Int J Mol Sci 2020 Apr 8;21(7). Epub 2020 Apr 8.

Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.

Patients with very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) can present with life-threatening cardiac arrhythmias. The pathophysiological mechanism is unknown. We reprogrammed fibroblasts from one mildly and one severely affected VLCADD patient, into human induced pluripotent stem cells (hiPSCs) and differentiated these into cardiomyocytes (VLCADD-CMs). VLCADD-CMs displayed shorter action potentials (APs), more delayed afterdepolarizations (DADs) and higher systolic and diastolic intracellular Ca concentration ([Ca]) than control CMs. The mitochondrial booster resveratrol mitigated the biochemical, electrophysiological and [Ca] changes in the mild but not in the severe VLCADD-CMs. Accumulation of potentially toxic intermediates of fatty acid oxidation was blocked by substrate reduction with etomoxir. Incubation with etomoxir led to marked prolongation of AP duration and reduced DADs and [Ca] in both VLCADD-CMs. These results provide compelling evidence that reduced accumulation of fatty acid oxidation intermediates, either by enhanced fatty acid oxidation flux through increased mitochondria biogenesis (resveratrol) or by inhibition of fatty acid transport into the mitochondria (etomoxir), rescues pro-arrhythmia defects in VLCADD-CMs and open doors for new treatments.
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http://dx.doi.org/10.3390/ijms21072589DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177397PMC
April 2020

Sibling history is associated with heart failure after a first myocardial infarction.

Open Heart 2020 24;7(1):e001143. Epub 2020 Mar 24.

Department of Cardiology, The Heart Centre, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.

Objective: Morbidity and mortality due to heart failure (HF) as a complication of myocardial infarction (MI) is high, and remains among the leading causes of death and hospitalisation. This study investigated the association between family history of MI with or without HF, and the risk of developing HF after first MI.

Methods: Through nationwide registries, we identified all individuals aged 18-50 years hospitalised with first MI from 1997 to 2016 in Denmark. We identified 13 810 patients with MI, and the cohort was followed until HF diagnosis, second MI, 3 years after index MI, emigration, death or the end of 2016, whichever occurred first. HRs were estimated by Cox hazard regression models adjusted for sex, age, calendar year and comorbidities (reference: patients with no family history of MI).

Results: After adjustment, we observed an increased risk of MI-induced HF for those having a sibling with MI with HF (HR 2.05, 95% CI 1.02 to 4.12). Those having a sibling with MI without HF also had a significant, but lower increased risk of HF (HR 1.39, 95% CI 1.05 to 1.84). Parental history of MI with or without HF was not associated with HF.

Conclusion: In this nationwide cohort, sibling history of MI with or without HF was associated with increased risk of HF after first MI, while a parental family history was not, suggesting that shared environmental factors may predominate in the determination of risk for developing HF.
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http://dx.doi.org/10.1136/openhrt-2019-001143DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7103809PMC
June 2020

SARS-CoV-2, COVID-19, and inherited arrhythmia syndromes.

Heart Rhythm 2020 09 31;17(9):1456-1462. Epub 2020 Mar 31.

Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Heart Center, Amsterdam, The Netherlands; European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart (ERN GUARD-Heart). Electronic address:

Ever since the first case was reported at the end of 2019, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the associated coronavirus disease 2019 (COVID-19) has become a serious threat to public health globally in short time. At this point in time, there is no proven effective therapy. The interactions with concomitant disease are largely unknown, and that may be particularly pertinent to inherited arrhythmia syndrome. An arrhythmogenic effect of COVID-19 can be expected, potentially contributing to disease outcome. This may be of importance for patients with an increased risk of cardiac arrhythmias, either secondary to acquired conditions or comorbidities or consequent to inherited syndromes. Management of patients with inherited arrhythmia syndromes such as long QT syndrome, Brugada syndrome, short QT syndrome, and catecholaminergic polymorphic ventricular tachycardia in the setting of the COVID-19 pandemic may prove particularly challenging. Depending on the inherited defect involved, these patients may be susceptible to proarrhythmic effects of COVID-19-related issues such as fever, stress, electrolyte disturbances, and use of antiviral drugs. Here, we describe the potential COVID-19-associated risks and therapeutic considerations for patients with distinct inherited arrhythmia syndromes and provide recommendations, pending local possibilities, for their monitoring and management during this pandemic.
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http://dx.doi.org/10.1016/j.hrthm.2020.03.024DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7156157PMC
September 2020

Research in understudied populations offers local and global insights into the genetics of hypertrophic cardiomyopathy.

Pol Arch Intern Med 2020 02 27;130(2):76-78. Epub 2020 Feb 27.

Department of Clinical and Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands

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http://dx.doi.org/10.20452/pamw.15214DOI Listing
February 2020

Seasonality of ventricular fibrillation at first myocardial infarction and association with viral exposure.

PLoS One 2020 26;15(2):e0226936. Epub 2020 Feb 26.

The Heart Centre, Department of Cardiology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.

Aims: To investigate seasonality and association of increased enterovirus and influenza activity in the community with ventricular fibrillation (VF) risk during first ST-elevation myocardial infarction (STEMI).

Methods: This study comprised all consecutive patients with first STEMI (n = 4,659; aged 18-80 years) admitted to the invasive catheterization laboratory between 2010-2016, at Copenhagen University Hospital, Rigshospitalet, covering eastern Denmark (2.6 million inhabitants, 45% of the Danish population). Hospital admission, prescription, and vital status data were assessed using Danish nationwide registries. We utilized monthly/weekly surveillance data for enterovirus and influenza from the Danish National Microbiology Database (2010-2016) that receives copies of laboratory tests from all Danish departments of clinical microbiology.

Results: Of the 4,659 consecutively enrolled STEMI patients, 581 (12%) had VF before primary percutaneous coronary intervention. In a subset (n = 807), we found that VF patients experienced more generalized fatigue and flu-like symptoms within 7 days before STEMI compared with the patients without VF (OR 3.39, 95% CI 1.76-6.54). During the study period, 2,704 individuals were diagnosed with enterovirus and 19,742 with influenza. No significant association between enterovirus and VF (OR 1.00, 95% CI 0.99-1.02), influenza and VF (OR 1.00, 95% CI 1.00-1.00), or week number and VF (p-value 0.94 for enterovirus and 0.89 for influenza) was found.

Conclusion: We found no clear seasonality of VF during first STEMI. Even though VF patients had experienced more generalized fatigue and flu-like symptoms within 7 days before STEMI compared with patients without VF, no relationship was found between enterovirus or influenza exposure and occurrence of VF.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0226936PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7043782PMC
May 2020

Scientists on the Spot: The complex inheritance of cardiac disorders.

Cardiovasc Res 2020 01;116(1):e11

Amsterdam UMC, AMC Heart Center, Department of Clinical & Experimental Cardiology, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.

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http://dx.doi.org/10.1093/cvr/cvz295DOI Listing
January 2020

Predicting Risk for Adult-Onset Sudden Cardiac Death in the Population.

J Am Coll Cardiol 2019 11 11;74(21):2635-2637. Epub 2019 Nov 11.

Amsterdam University Medical Center, University of Amsterdam, Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam, the Netherlands. Electronic address: https://twitter.com/NajimLahrouchi.

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http://dx.doi.org/10.1016/j.jacc.2019.09.024DOI Listing
November 2019

Functional Consequences of the -p.Y1977N Mutation within the PY Ubiquitylation Motif: Discrepancy between HEK293 Cells and Transgenic Mice.

Int J Mol Sci 2019 Oct 11;20(20). Epub 2019 Oct 11.

Department of Clinical and Experimental Cardiology, Heart Centre, Amsterdam UMC, Location Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 Amsterdam, The Netherlands.

Dysfunction of the cardiac sodium channel Nav1.5 (encoded by the gene) is associated with arrhythmias and sudden cardiac death. mutations associated with long QT syndrome type 3 (LQT3) lead to enhanced late sodium current and consequent action potential (AP) prolongation. Internalization and degradation of Na1.5 is regulated by ubiquitylation, a post-translational mechanism that involves binding of the ubiquitin ligase Nedd4-2 to a proline-proline-serine-tyrosine sequence of Na1.5, designated the PY-motif. We investigated the biophysical properties of the LQT3-associated -p.Y1977N mutation located in the Na1.5 PY-motif, both in HEK293 cells as well as in newly generated mice harboring the mouse homolog mutation -p.Y1981N. We found that in HEK293 cells, the -p.Y1977N mutation abolished the interaction between Na1.5 and Nedd4-2, suppressed PY-motif-dependent ubiquitylation of Na1.5, and consequently abrogated Nedd4-2 induced sodium current (I) decrease. Nevertheless, homozygous mice harboring the -p.Y1981N mutation showed no electrophysiological alterations nor changes in AP or (late) I properties, questioning the in vivo relevance of the PY-motif. Our findings suggest the presence of compensatory mechanisms, with additional, as yet unknown, factors likely required to reduce the "ubiquitylation reserve" of Na1.5. Future identification of such modulatory factors may identify potential triggers for arrhythmias and sudden cardiac death in the setting of LQT3 mutations.
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http://dx.doi.org/10.3390/ijms20205033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6829230PMC
October 2019

Epidemiology of inherited arrhythmias.

Nat Rev Cardiol 2020 04 3;17(4):205-215. Epub 2019 Oct 3.

Department of Clinical and Experimental Cardiology, Heart Center, Academic Medical Center, Amsterdam, Netherlands.

The primary electrical disorders are a group of inherited cardiac ventricular arrhythmias that are a major cause of sudden cardiac death in young individuals. Inherited ventricular arrhythmias result from mutations in genes encoding cardiac ion channels or their modulatory subunits. Advances in genetic screening in the past three decades have led to the assembly of large patient cohorts with these disorders. Studies in these patients, as well as in the general population, have striven to define the prevalence of these inherited arrhythmias and the characteristics of patients with different genetic subtypes of the disease. In this Review, we provide a comprehensive update on the epidemiology of inherited ventricular arrhythmias, focusing on natural history, prevalence and patient demographics. In addition, we summarize the various founder populations (groups of individuals with a disease that is caused by a genetic defect inherited from a common ancestor) that have been identified for some of these disorders and which lead to increased prevalence in some geographical regions. To date, although numerous studies have markedly increased our understanding of the epidemiology of these disorders, demographic data, especially from non-Western countries, remain scarce. Furthermore, defining the true prevalence of these disorders remains challenging. International collaboration will undoubtedly accelerate the collection of demographic information and improve the accuracy of prevalence data.
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http://dx.doi.org/10.1038/s41569-019-0266-2DOI Listing
April 2020

The yield of postmortem genetic testing in sudden death cases with structural findings at autopsy.

Eur J Hum Genet 2020 01 18;28(1):17-22. Epub 2019 Sep 18.

Molecular and Clinical Sciences Research Institute, St. George's, University of London, London, UK.

Sudden cardiac death (SCD) is often associated with structural abnormalities of the heart during autopsy. This study sought to compare the diagnostic yield of postmortem genetic testing in (1) cases with structural findings of uncertain significance at autopsy to (2) cases with autopsy findings diagnostic of cardiomyopathy. We evaluated 57 SCD cases with structural findings at cardiac autopsy. Next-generation sequencing using a panel of 77 primary electrical disorder and cardiomyopathy genes was performed. Pathogenic and likely pathogenic variants were classified using American College of Medical Genetics (ACMG) consensus guidelines. In 29 cases (51%) autopsy findings of uncertain significance were identified whereas in 28 cases (49%) a diagnosis of cardiomyopathy was established. We identified a pathogenic or likely pathogenic variant in 10 cases (18%); in 1 (3%) case with non-specific autopsy findings compared with 9 (32%) cases with autopsy findings diagnostic of cardiomyopathy (p = 0.0054). The yield of genetic testing in SCD cases with autopsy findings consistent with cardiomyopathy is comparable with the yield in cardiomyopathy patients that are alive. Genetic testing in cases with findings of uncertain significance offers lower clinical utility than in cardiomyopathy, with lower yields than detected previously. This highlights the need for stringent evaluation of variant pathogenicity.
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http://dx.doi.org/10.1038/s41431-019-0500-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6906523PMC
January 2020

Predicting cardiac electrical response to sodium-channel blockade and Brugada syndrome using polygenic risk scores.

Eur Heart J 2019 10;40(37):3097-3107

Department of Clinical and Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Heart Center, Amsterdam Cardiovascular Sciences, Meibergdreef 9, AZ Amsterdam, The Netherlands.

Aims: Sodium-channel blockers (SCBs) are associated with arrhythmia, but variability of cardiac electrical response remains unexplained. We sought to identify predictors of ajmaline-induced PR and QRS changes and Type I Brugada syndrome (BrS) electrocardiogram (ECG).

Methods And Results: In 1368 patients that underwent ajmaline infusion for suspected BrS, we performed measurements of 26 721 ECGs, dose-response mixed modelling and genotyping. We calculated polygenic risk scores (PRS) for PR interval (PRSPR), QRS duration (PRSQRS), and Brugada syndrome (PRSBrS) derived from published genome-wide association studies and used regression analysis to identify predictors of ajmaline dose related PR change (slope) and QRS slope. We derived and validated using bootstrapping a predictive model for ajmaline-induced Type I BrS ECG. Higher PRSPR, baseline PR, and female sex are associated with more pronounced PR slope, while PRSQRS and age are positively associated with QRS slope (P < 0.01 for all). PRSBrS, baseline QRS duration, presence of Type II or III BrS ECG at baseline, and family history of BrS are independently associated with the occurrence of a Type I BrS ECG, with good predictive accuracy (optimism-corrected C-statistic 0.74).

Conclusion: We show for the first time that genetic factors underlie the variability of cardiac electrical response to SCB. PRSBrS, family history, and a baseline ECG can predict the development of a diagnostic drug-induced Type I BrS ECG with clinically relevant accuracy. These findings could lead to the use of PRS in the diagnosis of BrS and, if confirmed in population studies, to identify patients at risk for toxicity when given SCB.
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http://dx.doi.org/10.1093/eurheartj/ehz435DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6769824PMC
October 2019

Blood Pressure-Associated Genetic Variants in the Natriuretic Peptide Receptor 1 Gene Modulate Guanylate Cyclase Activity.

Circ Genom Precis Med 2019 08 20;12(8):e002472. Epub 2019 Aug 20.

Center for Genomic Medicine (N.L., C.N.-C.), Massachusetts General Hospital Research Institute and Harvard Medical School, Boston.

Background: Human genetic variation in the NPR1 (natriuretic peptide receptor 1 gene, encoding NPR-A, atrial natriuretic peptide receptor 1) was recently shown to affect blood pressure (BP). NPR-A catalyzes the intracellular conversion of guanosine triphosphate to cGMP (cyclic 3',5'-guanosine monophosphate) on binding of ANP, BNP (atrial or brain natriuretic peptide). Increased levels of cGMP decrease BP by inducing natriuresis, diuresis, and vasodilation.

Methods: We performed a meta-analysis of low-frequency and rare NPR1 variants for BP association in up to 491 584 unrelated individuals. To examine whether the identified BP-associated variants affect NPR-A function, the cGMP response to ANP and BNP was measured in cells expressing wild-type NPR1 and cells expressing the NPR1 variants.

Results: In this study, we identified BP associations of 3 amino acid altering variants of NPR1. The minor alleles of rs35479618 (p.E967K, gnomAD non-Finnish European allele frequency 0.017) and rs116245325 (p.L1034F, allele frequency 0.0007) were associated with higher BP (P=4.0×10 and P=9.9×10, respectively), while the minor allele of rs61757359 (p.G541S, allele frequency 0.003) was associated with lower BP (P=1.8×10). Cells transiently expressing 967K or 1034F NPR-A displayed decreased cGMP production in response to ANP and BNP (all P<10), while cells expressing 541S NPR-A produced more cGMP compared with cells expressing wild-type NPR-A (P≤4.13×10 for ANP and P≤4.24×10 for BNP).

Conclusions: In summary, the loss or gain of guanylate cyclase activity for these NPR1 allelic variants could explain the higher or lower BP observed for carriers in large population-based studies.
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http://dx.doi.org/10.1161/CIRCGEN.119.002472DOI Listing
August 2019

Beyond the One Gene-One Disease Paradigm: Complex Genetics and Pleiotropy in Inheritable Cardiac Disorders

Circulation 2019 08 12;140(7):595-610. Epub 2019 Aug 12.

Leon H. Charney Division of Cardiology (M.C., M.D.), NYU School of Medicine, New York.

Inheritable cardiac disorders, which may be associated with cardiomyopathic changes, are often associated with increased risk of sudden death in the young. Early linkage analysis studies in Mendelian forms of these diseases, such as hypertrophic cardiomyopathy and long-QT syndrome, uncovered large-effect genetic variants that contribute to the phenotype. In more recent years, through genotype-phenotype studies and methodological advances in genetics, it has become evident that most inheritable cardiac disorders are not monogenic but, rather, have a complex genetic basis wherein multiple genetic variants contribute (oligogenic or polygenic inheritance). Conversely, studies on genes underlying these disorders uncovered pleiotropic effects, with a single gene affecting multiple and apparently unrelated phenotypes. In this review, we explore these 2 phenomena: on the one hand, the evidence that variants in multiple genes converge to generate one clinical phenotype, and, on the other, the evidence that variants in one gene can lead to apparently unrelated phenotypes. Although multiple conditions are addressed to illustrate these concepts, the experience obtained in the study of long-QT syndrome, Brugada syndrome, and arrhythmogenic cardiomyopathy, and in the study of functions related to SCN5A (the gene coding for the α-subunit of the most abundant sodium channel in the heart) and PKP2 (the gene coding for the desmosomal protein plakophilin-2), as well, is discussed in more detail.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.118.035954DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6697136PMC
August 2019

GATA6 mutations: Characterization of two novel patients and a comprehensive overview of the GATA6 genotypic and phenotypic spectrum.

Am J Med Genet A 2019 09 12;179(9):1836-1845. Epub 2019 Jul 12.

Department of Clinical Genetics, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.

The first human mutations in GATA6 were described in a cohort of patients with persistent truncus arteriosus, and the phenotypic spectrum has expanded since then. This study underscores the broad phenotypic spectrum by presenting two patients with de novo GATA6 mutations, both exhibiting complex cardiac defects, pancreatic, and other abnormalities. Furthermore, we provided a detailed overview of all published human genetic variation in/near GATA6 published to date and the associated phenotypes (n = 78). We conclude that the most common phenotypes associated with a mutation in GATA6 were structural cardiac and pancreatic abnormalities, with a penetrance of 87 and 60%, respectively. Other common malformations were gallbladder agenesis, congenital diaphragmatic hernia, and neurocognitive abnormalities, mostly developmental delay. Fifty-eight percent of the mutations were de novo, and these patients more often had an anomaly of intracardiac connections, an anomaly of the great arteries, and hypothyroidism, compared with those with inherited mutations. Functional studies mostly support loss-of-function as the pathophysiological mechanism. In conclusion, GATA6 mutations give a wide range of phenotypic defects, most frequently malformations of the heart and pancreas. This highlights the importance of detailed clinical evaluation of identified carriers to evaluate their full phenotypic spectrum.
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http://dx.doi.org/10.1002/ajmg.a.61294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6772993PMC
September 2019