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The irregular pulse that we now call atrial fibrillation (AF) was first described in 1628 by William Harvey in his I Exercitatio de Motu Cordis i .[1] A few centuries later, Einthoven first recorded AF on the electrocardiogram. Therefore, accounting for clinical risk factors is not expected to affect its association with AF and hence its predictive value.[4] The study participants had established cardiovascular conditions and were therefore at higher risk of incident AF, reflected in a relatively high 3-year incidence rate of AF of 3.6%. P.K. is listed as inventor on two patents held by University of Birmingham (Atrial Fibrillation Therapy WO 2015140571, Markers for Atrial Fibrillation WO 2016012783). [Extracted from the article]

Aims: Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in man, causing substantial morbidity and mortality with a major worldwide public health impact. It is increasingly recognized as a highly heritable condition. This study aimed to determine genetic risk factors for early-onset AF. Methods and results; We sequenced the whole genomes of 8453 Icelanders and imputed genotypes of the 25.5 million sequence variants we discovered into 1799 Icelanders with early-onset AF (diagnosed before 60 years of age) and 337 453 controls. Each sequence variant was tested for association based on multiplicative and recessive inheritance models. We discovered a rare frameshift deletion in the myosin MYL4 gene (c.234delC) that associates with early-onset AF under a recessive mode of inheritance (allelic frequency¼0.58%). We found eight homozygous carriers of the mutation, all of whom had early-onset AF. Six of the homozygotes were diagnosed by the age of 30 and the remaining two in their 50s. Three of the homozygotes had received pacemaker implantations due to sick sinus syndrome, three had suffered an ischemic stroke, and one suffered sudden cardiac death. Conclusions: Through a population approach we found a loss of function mutation in the myosin gene MYL4 that, in the homozygous state, is completely penetrant for early-onset AF. The finding may provide novel mechanistic insight into the pathophysiology of this complex arrhythmia. [ABSTRACT FROM AUTHOR]

Aims: Syncope is a common and clinically challenging condition. In this study, the genetics of syncope were investigated to seek knowledge about its pathophysiology and prognostic implications., Methods and Results: This genome-wide association meta-analysis included 56 071 syncope cases and 890 790 controls from deCODE genetics (Iceland), UK Biobank (United Kingdom), and Copenhagen Hospital Biobank Cardiovascular Study/Danish Blood Donor Study (Denmark), with a follow-up assessment of variants in 22 412 cases and 286 003 controls from Intermountain (Utah, USA) and FinnGen (Finland). The study yielded 18 independent syncope variants, 17 of which were novel. One of the variants, p.Ser140Thr in PTPRN2, affected syncope only when maternally inherited. Another variant associated with a vasovagal reaction during blood donation and five others with heart rate and/or blood pressure regulation, with variable directions of effects. None of the 18 associations could be attributed to cardiovascular or other disorders. Annotation with regard to regulatory elements indicated that the syncope variants were preferentially located in neural-specific regulatory regions. Mendelian randomization analysis supported a causal effect of coronary artery disease on syncope. A polygenic score (PGS) for syncope captured genetic correlation with cardiovascular disorders, diabetes, depression, and shortened lifespan. However, a score based solely on the 18 syncope variants performed similarly to the PGS in detecting syncope risk but did not associate with other disorders., Conclusion: The results demonstrate that syncope has a distinct genetic architecture that implicates neural regulatory processes and a complex relationship with heart rate and blood pressure regulation. A shared genetic background with poor cardiovascular health was observed, supporting the importance of a thorough assessment of individuals presenting with syncope., Competing Interests: Conflicts of interest: The following authors are employees of deCODE genetics/Amgen, Inc.: Hildur M Aegisdottir, Rosa B Thorolfsdottir, Gardar Sveinbjornsson, Olafur A Stefansson, Bjarni Gunnarsson, Vinicius Tragante, Lilja Stefansdottir, Thorgeir E Thorgeirsson, Egil Ferkingstad, Gudmar Thorleifsson, Michael L Frigge, Kristjan E Hjorleifsson, Erna V Ivarsdottir, Anna Helgadottir, Solveig Gretarsdottir, Valgerdur Steinthorsdottir, Asmundur Oddsson, Hannes P Eggertsson, Gisli H Halldorsson, Patrick Sulem, Gudmundur Norddahl, Gudrun Rutsdottir, Gudmundur Thorgeirsson, David O Arnar, Unnur Thorsteinsdottir, Daniel F Gudbjartsson, Hilma Holm, and Kari Stefansson. Karina Banasik and Søren Brunak acknowledge the Novo Nordisk Foundation (grants NNF17OC0027594 and NNF14CC0001)., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Aims: The aim of this study was to use human genetics to investigate the pathogenesis of sick sinus syndrome (SSS) and the role of risk factors in its development., Methods and Results: We performed a genome-wide association study of 6469 SSS cases and 1 000 187 controls from deCODE genetics, the Copenhagen Hospital Biobank, UK Biobank, and the HUNT study. Variants at six loci associated with SSS, a reported missense variant in MYH6, known atrial fibrillation (AF)/electrocardiogram variants at PITX2, ZFHX3, TTN/CCDC141, and SCN10A and a low-frequency (MAF = 1.1-1.8%) missense variant, p.Gly62Cys in KRT8 encoding the intermediate filament protein keratin 8. A full genotypic model best described the p.Gly62Cys association (P = 1.6 × 10-20), with an odds ratio (OR) of 1.44 for heterozygotes and a disproportionally large OR of 13.99 for homozygotes. All the SSS variants increased the risk of pacemaker implantation. Their association with AF varied and p.Gly62Cys was the only variant not associating with any other arrhythmia or cardiovascular disease. We tested 17 exposure phenotypes in polygenic score (PGS) and Mendelian randomization analyses. Only two associated with the risk of SSS in Mendelian randomization, AF, and lower heart rate, suggesting causality. Powerful PGS analyses provided convincing evidence against causal associations for body mass index, cholesterol, triglycerides, and type 2 diabetes (P > 0.05)., Conclusion: We report the associations of variants at six loci with SSS, including a missense variant in KRT8 that confers high risk in homozygotes and points to a mechanism specific to SSS development. Mendelian randomization supports a causal role for AF in the development of SSS., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)