151
|
Abstract
Atrial fibrillation (AF) sometimes develops in younger individuals without any evident cardiac or other disease. To refer to these patients who were considered to have a very favourable prognosis compared with other AF patients, the term 'lone' AF was introduced in 1953. However, there are numerous uncertainties associated with 'lone' AF, including inconsistent entity definitions, considerable variations in the reported prevalence and outcomes, etc. Indeed, increasing evidence suggests a number of often subtle cardiac alterations associated with apparently 'lone' AF, which may have relevant prognostic implications. Hence, 'lone' AF patients comprise a rather heterogeneous cohort, and may have largely variable risk profiles based on the presence (or absence) of overlooked subclinical cardiovascular risk factors or genetically determined subtle alterations at the cellular or molecular level. Whether the implementation of various cardiac imaging techniques, biomarkers and genetic information could improve the prediction of risk for incident AF and risk assessment of 'lone' AF patients, and influence the treatment decisions needs further research. In this review, we summarise the current knowledge on 'lone' AF, highlight the existing inconsistencies in the field and discuss the prognostic and treatment implications of recent insights in 'lone' AF pathophysiology.
Collapse
Affiliation(s)
- T S Potpara
- Cardiology Clinic, Clinical Centre of Serbia, Belgrade, Serbia; Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | | |
Collapse
|
152
|
Torrado M, Franco D, Hernández-Torres F, Crespo-Leiro MG, Iglesias-Gil C, Castro-Beiras A, Mikhailov AT. Pitx2c is reactivated in the failing myocardium and stimulates myf5 expression in cultured cardiomyocytes. PLoS One 2014; 9:e90561. [PMID: 24595098 PMCID: PMC3942452 DOI: 10.1371/journal.pone.0090561] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 02/01/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Pitx2 (paired-like homeodomain 2 transcription factor) is crucial for heart development, but its role in heart failure (HF) remains uncertain. The present study lays the groundwork implicating Pitx2 signalling in different modalities of HF. METHODOLOGY/PRINCIPAL FINDINGS A variety of molecular, cell-based, biochemical, and immunochemical assays were used to evaluate: (1) Pitx2c expression in the porcine model of diastolic HF (DHF) and in patients with systolic HF (SHF) due to dilated and ischemic cardiomyopathy, and (2) molecular consequences of Pitx2c expression manipulation in cardiomyocytes in vitro. In pigs, the expression of Pitx2c, physiologically downregulated in the postnatal heart, is significantly re-activated in left ventricular (LV) failing myocardium which, in turn, is associated with increased expression of a restrictive set of Pitx2 target genes. Among these, Myf5 was identified as the top upregulated gene. In vitro, forced expression of Pitx2c in cardiomyocytes, but not in skeletal myoblasts, activates Myf5 in dose-dependent manner. In addition, we demonstrate that the level of Pitx2c is upregulated in the LV-myocardium of SHF patients. CONCLUSIONS/SIGNIFICANCE The results provide previously unrecognized evidence that Pitx2c is similarly reactivated in postnatal/adult heart at distinct HF phenotypes and suggest that Pitx2c is involved, directly or indirectly, in the regulation of Myf5 expression in cardiomyocytes.
Collapse
Affiliation(s)
- Mario Torrado
- Institute of Health Sciences, University of La Coruña, La Coruña, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, Jaen, Spain
| | | | | | | | - Alfonso Castro-Beiras
- Institute of Health Sciences, University of La Coruña, La Coruña, Spain
- University Hospital Center of La Coruña, La Coruña, Spain
| | | |
Collapse
|
153
|
Olesen MS, Nielsen MW, Haunsø S, Svendsen JH. Atrial fibrillation: the role of common and rare genetic variants. Eur J Hum Genet 2014; 22:297-306. [PMID: 23838598 PMCID: PMC3925267 DOI: 10.1038/ejhg.2013.139] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 04/28/2013] [Accepted: 05/27/2013] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia affecting 1-2% of the general population. A number of studies have demonstrated that AF, and in particular lone AF, has a substantial genetic component. Monogenic mutations in lone and familial AF, although rare, have been recognized for many years. Presently, mutations in 25 genes have been associated with AF. However, the complexity of monogenic AF is illustrated by the recent finding that both gain- and loss-of-function mutations in the same gene can cause AF. Genome-wide association studies (GWAS) have indicated that common single-nucleotide polymorphisms (SNPs) have a role in the development of AF. Following the first GWAS discovering the association between PITX2 and AF, several new GWAS reports have identified SNPs associated with susceptibility of AF. To date, nine SNPs have been associated with AF. The exact biological pathways involving these SNPs and the development of AF are now starting to be elucidated. Since the first GWAS, the number of papers concerning the genetic basis of AF has increased drastically and the majority of these papers are for the first time included in a review. In this review, we discuss the genetic basis of AF and the role of both common and rare genetic variants in the susceptibility of developing AF. Furthermore, all rare variants reported to be associated with AF were systematically searched for in the Exome Sequencing Project Exome Variant Server.
Collapse
Affiliation(s)
- Morten S Olesen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Morten W Nielsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Surgery and Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jesper H Svendsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
- Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
- Department of Surgery and Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
154
|
|
155
|
Tao Y, Zhang M, Li L, Bai Y, Zhou Y, Moon AM, Kaminski HJ, Martin JF. Pitx2, an atrial fibrillation predisposition gene, directly regulates ion transport and intercalated disc genes. CIRCULATION. CARDIOVASCULAR GENETICS 2014; 7:23-32. [PMID: 24395921 PMCID: PMC4013500 DOI: 10.1161/circgenetics.113.000259] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Pitx2 is the homeobox gene located in proximity to the human 4q25 familial atrial fibrillation (AF) locus. When deleted in the mouse germline, Pitx2 haploinsufficiency predisposes to pacing-induced AF, indicating that reduced Pitx2 promotes an arrhythmogenic substrate. Previous work focused on Pitx2 developmental functions that predispose to AF. Although Pitx2 is expressed in postnatal left atrium, it is unknown whether Pitx2 has distinct postnatal and developmental functions. METHODS AND RESULTS To investigate Pitx2 postnatal function, we conditionally inactivated Pitx2 in the postnatal atrium while leaving its developmental function intact. Unstressed adult Pitx2 homozygous mutant mice display variable R-R interval with diminished P-wave amplitude characteristic of sinus node dysfunction, an AF risk factor in human patients. An integrated genomics approach in the adult heart revealed Pitx2 target genes encoding cell junction proteins, ion channels, and critical transcriptional regulators. Importantly, many Pitx2 target genes have been implicated in human AF by genome-wide association studies. Immunofluorescence and transmission electron microscopy studies in adult Pitx2 mutant mice revealed structural remodeling of the intercalated disc characteristic of human patients with AF. CONCLUSIONS Our findings, revealing that Pitx2 has genetically separable postnatal and developmental functions, unveil direct Pitx2 target genes that include channel and calcium handling genes, as well as genes that stabilize the intercalated disc in postnatal atrium.
Collapse
Affiliation(s)
- Ye Tao
- Department of Molecular Physiology and Biophysics, Texas Heart Institute, Houston, TX
| | - Min Zhang
- Department of Molecular Physiology and Biophysics, Texas Heart Institute, Houston, TX
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX
| | - Lele Li
- Department of Molecular Physiology and Biophysics, Texas Heart Institute, Houston, TX
- Cardiomyocyte Renewal Lab, Texas Heart Institute, Houston, TX
| | - Yan Bai
- Department of Molecular Physiology and Biophysics, Texas Heart Institute, Houston, TX
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX
| | - Yuefang Zhou
- Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Anne M. Moon
- Weis Center for Research, Geisinger Clinic, Danville PA
| | - Henry J. Kaminski
- Department of Neurology, George Washington University, Washington, DC
| | - James F. Martin
- Department of Molecular Physiology and Biophysics, Texas Heart Institute, Houston, TX
- Cardiomyocyte Renewal Lab, Texas Heart Institute, Houston, TX
- Institute of Biosciences and Technology, Texas A&M Health Science Center, Houston, TX
- Program in Developmental Biology, Baylor College of Medicine, Texas Heart Institute, Houston, TX
| |
Collapse
|
156
|
Balouch MA, Kolek MJ, Darbar D. Improved understanding of the pathophysiology of atrial fibrillation through the lens of discrete pathological pathways. Glob Cardiol Sci Pract 2014; 2014:24-36. [PMID: 25054116 PMCID: PMC4104374 DOI: 10.5339/gcsp.2014.5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 03/19/2014] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is a common disorder with a complex and incompletely understood pathophysiology. Genetic approaches to understanding the pathophysiology of AF have led to the identification of several biological pathways important in the pathogenesis of the arrhythmia. These include pathways important for cardiac development, generation and propagation of atrial electrical impulses, and atrial remodeling and fibrosis. While common and rare genetic variants in these pathways are associated with increased susceptibility to AF, they differ substantially among patients with lone versus typical AF. Furthermore, how these pathways converge to a final common clinical phenotype of AF is unclear and might also vary among different patient populations. Here, we review the contemporary knowledge of AF pathogenesis and discuss how derangement in cardiac development, ion channel dysfunction, and promotion of atrial fibrosis may contribute to this common and important clinical disorder.
Collapse
Affiliation(s)
- Muhammad A Balouch
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Matthew J Kolek
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Dawood Darbar
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| |
Collapse
|
157
|
Gore-Panter SR, Hsu J, Hanna P, Gillinov AM, Pettersson G, Newton DW, Moravec CS, Van Wagoner DR, Chung MK, Barnard J, Smith JD. Atrial Fibrillation associated chromosome 4q25 variants are not associated with PITX2c expression in human adult left atrial appendages. PLoS One 2014; 9:e86245. [PMID: 24465984 PMCID: PMC3899225 DOI: 10.1371/journal.pone.0086245] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 12/11/2013] [Indexed: 01/08/2023] Open
Abstract
Atrial Fibrillation (AF), the most common sustained arrhythmia, has a strong genetic component, but the mechanism by which common genetic variants lead to increased AF susceptibility is unknown. Genome-wide association studies (GWAS) have identified that the single nucleotide polymorphisms (SNPs) most strongly associated with AF are located on chromosome 4q25 in an intergenic region distal to the PITX2 gene. Our objective was to determine whether the AF-associated SNPs on chromosome 4q25 were associated with PITX2c expression in adult human left atrial appendages. Analysis of a lone AF GWAS identified four independent AF risk SNPs at chromosome 4q25. Human adult left atrial appendage tissue was obtained from 239 subjects of European Ancestry and used for SNP analysis of genomic DNA and determination of PITX2c RNA expression levels by quantitative PCR. Subjects were divided into three groups based on their history of AF and pre-operative rhythm. AF rhythm subjects had higher PITX2c expression than those with history of AF but in sinus rhythm. PITX2c expression was not associated with the AF risk SNPs in human adult left atrial appendages in all subjects combined or in each of the three subgroups. However, we identified seven SNPs modestly associated with PITX2c expression located in the introns of the ENPEP gene, ∼54 kb proximal to PITX2. PITX2c expression in human adult left atrial appendages is not associated with the chromosome 4q25 AF risk SNPs; thus, the mechanism by which these SNPs are associated with AF remains enigmatic.
Collapse
Affiliation(s)
- Shamone R. Gore-Panter
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Jeffery Hsu
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Peter Hanna
- Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
| | - A. Marc Gillinov
- Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Gosta Pettersson
- Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - David W. Newton
- Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Christine S. Moravec
- Department of Molecular Cardiology, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - David R. Van Wagoner
- Department of Molecular Cardiology, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Mina K. Chung
- Department of Molecular Cardiology, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - John Barnard
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Jonathan D. Smith
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, Ohio, United States of America
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Molecular Cardiology, Cleveland Clinic, Cleveland, Ohio, United States of America
| |
Collapse
|
158
|
Kolek MJ, Parvez B, Muhammad R, Shoemaker MB, Blair MA, Stubblefield T, Kucera GA, Denny JC, Roden DM, Darbar D. A common variant on chromosome 4q25 is associated with prolonged PR interval in subjects with and without atrial fibrillation. Am J Cardiol 2014; 113:309-13. [PMID: 24161141 DOI: 10.1016/j.amjcard.2013.08.045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/19/2013] [Accepted: 08/19/2013] [Indexed: 11/19/2022]
Abstract
Single nucleotide polymorphisms (SNPs) at chromosome 4q25 (near PITX2) are strongly associated with atrial fibrillation (AF). We assessed whether a 4q25-tagging SNP (rs2200733) is associated with PR interval duration in patients with lone and typical AF and controls. Patients with lone (n = 169) and typical (n = 269) AF enrolled in the Vanderbilt AF registry and controls (n = 1,403) derived from the Vanderbilt DNA Biobank were studied. Carriage of the rs2200733T allele (CT or TT genotype) was more common in patients with lone (39%) than typical (25%) AF or controls (21%, p <0.01 for both comparisons). In both AF cohorts, we observed an association between genotype and PR interval duration (median PR interval for CC, CT, and TT: 162, 178, and 176 ms, respectively, for lone, p = 0.038 and 166, 180, and 196 ms, respectively, for typical, p = 0.001). After adjustment for covariates, the association between T allele and PR prolongation persisted, with mean effect size of 10.9, 12.8, and 4.4 ms for patients with lone and typical AF and controls, respectively (p <0.05 for each comparison). We found that a common 4q25 AF susceptibility allele (rs2200733) is associated with PR interval prolongation in patients with lone and typical AF and controls with no AF. Given that prolonged PR interval is an established risk factor for AF, this observation, in the context of previously described functional effects of PITX2 deficiency, provides further knowledge about the pathophysiological link of 4q25 variants with AF.
Collapse
Affiliation(s)
- Matthew J Kolek
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Babar Parvez
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Raafia Muhammad
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - M Benjamin Shoemaker
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Marcia A Blair
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Tanya Stubblefield
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Gayle A Kucera
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Joshua C Denny
- Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dan M Roden
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Dawood Darbar
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee.
| |
Collapse
|
159
|
Wang J, Zhang DF, Sun YM, Yang YQ. A novel PITX2c loss-of-function mutation associated with familial atrial fibrillation. Eur J Med Genet 2014; 57:25-31. [PMID: 24333117 DOI: 10.1016/j.ejmg.2013.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 11/25/2013] [Indexed: 01/21/2023]
Abstract
Atrial fibrillation (AF) represents the most prevalent form of sustained cardiac arrhythmia and contributes substantially to cardiovascular morbidity and mortality. Aggregating evidence demonstrates that genetic risk factors play an important role in the pathogenesis of AF. However, AF is a genetically heterogeneous disease and the genetic defects responsible for AF in an overwhelming majority of patients remain unclear. In the present study, the whole coding region and splice junction sites of the PITX2c gene, which encodes a paired-like homeobox transcription factor essential for normal cardiovascular development, were sequenced in 160 unrelated patients with lone AF, and a novel heterozygous mutation, c.349C > T equivalent to p.P117S, was identified in a patient with positive family history of AF. The missense mutation, which co-segregated with AF in the family with complete penetrance and was absent in 700 unrelated ethnically matched healthy individuals, altered the amino acid completely conserved evolutionarily across species and was predicted to be pathogenic by MutationTaster and PolyPhen-2. Biological assays revealed that the mutant PITX2c protein was associated with significantly decreased transcriptional activity when compared with its wild-type counterpart. The findings implicate PITX2c loss-of-function mutation in familial AF for the first time, providing novel insight into the molecular pathology of AF.
Collapse
Affiliation(s)
- Jun Wang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, 150 Jimo Road, Shanghai 200120, China
| | - Dai-Fu Zhang
- Department of Cardiology, East Hospital, Tongji University School of Medicine, 150 Jimo Road, Shanghai 200120, China.
| | - Yu-Min Sun
- Department of Cardiology, Jing-An District Central Hospital, 259 Xikang Road, Shanghai 200040, China
| | - Yi-Qing Yang
- Department of Cardiology, Cardiovascular Research Laboratory and Central Laboratory, Shanghai Chest Hospital, Shanghai Jiao Tong University, 241 West Huaihai Road, Shanghai 200030, China.
| |
Collapse
|
160
|
Franco D, Christoffels VM, Campione M. Homeobox transcription factor Pitx2: The rise of an asymmetry gene in cardiogenesis and arrhythmogenesis. Trends Cardiovasc Med 2014; 24:23-31. [PMID: 23953978 DOI: 10.1016/j.tcm.2013.06.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/06/2013] [Accepted: 06/07/2013] [Indexed: 01/05/2023]
Abstract
The homeobox transcription factor Pitx2 displays a highly specific expression pattern during embryogenesis. Gain and loss of function experiments have unraveled its pivotal role in left-right signaling. Conditional deletion in mice has demonstrated a complex and intricate role for Pitx2 in distinct aspects of cardiac development and more recently a link to atrial fibrillation has been proposed based on genome-wide association studies. In this review we will revise the role of Pitx2 in the developing heart, starting from the early events of left-right determination followed by its role in cardiac morphogenesis and ending with its role in cardiac arrhythmogenesis.
Collapse
Affiliation(s)
- Diego Franco
- Department of Experimental Biology B3-362, University of Jaén, Jaen 23071, Spain.
| | | | - Marina Campione
- CNR-Institute of Neurosciences, Department of Biomedical Sciences, University of Padua, Padua, Italy
| |
Collapse
|
161
|
Qiu XB, Xu YJ, Li RG, Xu L, Liu X, Fang WY, Yang YQ, Qu XK. PITX2C loss-of-function mutations responsible for idiopathic atrial fibrillation. Clinics (Sao Paulo) 2014; 69:15-22. [PMID: 24473555 PMCID: PMC3870307 DOI: 10.6061/clinics/2014(01)03] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 07/10/2013] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE This study aimed to identify novel PITX2c mutations responsible for idiopathic atrial fibrillation. METHODS A cohort of 210 unrelated patients with idiopathic atrial fibrillation and 200 unrelated, ethnically matched healthy individuals used as controls were recruited. The whole coding exons and splice junctions of the PITX2c gene, which encodes a paired-like homeobox transcription factor required for normal cardiovascular morphogenesis, were sequenced in 210 patients and 200 control subjects. The causative potentials of the identified mutations were automatically predicted by MutationTaster and PolyPhen-2. The functional characteristics of the PITX2c mutations were explored using a dual-luciferase reporter assay system. RESULTS Two novel heterozygous PITX2c mutations (p.Q105L and p.R122C) were identified in 2 of the 210 unrelated patients with idiopathic atrial fibrillation. These missense mutations were absent in the 400 control chromosomes and were both predicted to be pathogenic. Multiple alignments of PITX2c protein sequences across various species showed that the altered amino acids were highly evolutionarily conserved. A functional analysis demonstrated that the mutant PITX2c proteins were both associated with significantly reduced transcriptional activity compared with their wild-type counterparts. CONCLUSION The findings of this study associate PITX2c loss-of-function mutations with atrial fibrillation, supporting the hypothesis that dysfunctional PITX2c confers enhanced susceptibility to atrial fibrillation and suggesting potential implications for early prophylaxis and allele-specific therapy for this common arrhythmia.
Collapse
Affiliation(s)
- Xing-Biao Qiu
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Ying-Jia Xu
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Ruo-Gu Li
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Lei Xu
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Xu Liu
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Wei-Yi Fang
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Yi-Qing Yang
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| | - Xin-Kai Qu
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, Shanghai Jiao Tong University, Shanghai Chest Hospital, Department of Cardiology and Cardiovascular Research, Shanghai, China
| |
Collapse
|
162
|
Roberts JD, Hsu JC, Aouizerat BE, Pullinger CR, Malloy MJ, Kane JP, Olgin JE, Marcus GM. Impact of a 4q25 genetic variant in atrial flutter and on the risk of atrial fibrillation after cavotricuspid isthmus ablation. J Cardiovasc Electrophysiol 2013; 25:271-277. [PMID: 24237655 DOI: 10.1111/jce.12317] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Revised: 09/21/2013] [Accepted: 09/24/2013] [Indexed: 01/08/2023]
Abstract
BACKGROUND The prediction of atrial fibrillation (AF) following catheter ablation of atrial flutter (Afl) would be helpful to facilitate targeted arrhythmia monitoring and anti-coagulation strategies. A single nucleotide polymorphism, rs2200733, is strongly associated with AF. We sought to characterize the association between rs2200733 and prevalent Afl and to determine if the variant could predict AF after cavotricuspid isthmus ablation. METHODS AND RESULTS We performed a genetic association study of 295 patients with Afl and/or AF and 469 controls using multivariable logistic regression. The variant was then assessed as a predictor of incident AF after cavotricuspid isthmus ablation in 87 consecutive typical Afl patients with Cox proportional hazards models. The rs2200733 rare allele was associated with an adjusted 2.06-fold increased odds of isolated Afl (95% CI: 1.13-3.76, P = 0.019) and an adjusted 2.79-fold increased odds of a combined phenotype of AF and Afl (95% CI: 1.81-4.28, P < 0.001). Following catheter ablation for Afl, carrier status of rs2200733 failed to predict an increased risk of AF either among all subjects (adjusted HR: 0.94; 95% CI: 0.58-1.53, P = 0.806) or among those with isolated Afl (adjusted HR: 1.29; 95% CI: 0.51-3.26, P = 0.585). CONCLUSIONS Our study demonstrates that Afl, whether occurring in isolation or along with AF, is associated with the rs2200733 AF risk allele. Genetic carrier status of rs2200733 failed to predict an increased risk of incident or recurrent AF following catheter ablation for Afl. These findings suggest that the causal mechanism associated with rs2200733 is germane to both AF and Afl.
Collapse
Affiliation(s)
- Jason D Roberts
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - Jonathan C Hsu
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California San Diego, San Diego, California, USA
| | - Bradley E Aouizerat
- Department of Physiological Nursing, University of California San Francisco, San Francisco, California, USA.,Institute for Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Clive R Pullinger
- Department of Physiological Nursing, University of California San Francisco, San Francisco, California, USA.,Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, USA
| | - Mary J Malloy
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, USA.,Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | - John P Kane
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, USA.,Department of Medicine, University of California San Francisco, San Francisco, California, USA.,Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, California, USA
| | - Jeffrey E Olgin
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California San Francisco, San Francisco, California, USA.,Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, USA
| | - Gregory M Marcus
- Section of Cardiac Electrophysiology, Division of Cardiology, Department of Medicine, University of California San Francisco, San Francisco, California, USA
| |
Collapse
|
163
|
Shi KH, Tao H, Yang JJ, Wu JX, Xu SS, Zhan HY. Role of microRNAs in atrial fibrillation: New insights and perspectives. Cell Signal 2013; 25:2079-84. [DOI: 10.1016/j.cellsig.2013.06.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 06/08/2013] [Accepted: 06/14/2013] [Indexed: 01/15/2023]
|
164
|
Yang YQ, Xu YJ, Li RG, Qu XK, Fang WY, Liu X. Prevalence and spectrum of PITX2c mutations associated with familial atrial fibrillation. Int J Cardiol 2013; 168:2873-6. [PMID: 23611745 DOI: 10.1016/j.ijcard.2013.03.141] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2013] [Accepted: 03/29/2013] [Indexed: 10/26/2022]
Affiliation(s)
- Yi-Qing Yang
- Department of Cardiology and Cardiovascular Research, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, 241 West Huaihai Road, Shanghai 200030, China.
| | | | | | | | | | | |
Collapse
|
165
|
Zhou YM, Zheng PX, Yang YQ, Ge ZM, Kang WQ. A novel PITX2c loss‑of‑function mutation underlies lone atrial fibrillation. Int J Mol Med 2013; 32:827-34. [PMID: 23913021 DOI: 10.3892/ijmm.2013.1463] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 07/29/2013] [Indexed: 11/05/2022] Open
Abstract
Atrial fibrillation (AF) is the most common form of sustained cardiac arrhythmia responsible for substantial morbidity and significantly increased mortality rates. A growing body of evidence documents the important role of genetic defects in the pathogenesis of AF. However, AF is a heterogeneous disease and the genetic determinants for AF in an overwhelming majority of patients remain unknown. In the present study, a cohort of 100 unrelated patients with lone AF and a total of 200 unrelated, ethnically matched healthy individuals used as controls, were recruited. The whole coding exons and splice junctions of the pituitary homeobox 2c (PITX2c) gene, which encodes a paired‑like homeobox transcription factor required for normal cardiovascular morphogenesis, were sequenced in the 100 patients and 200 control subjects. The causative potential of the identified mutation of PITX2c was predicted by MutationTaster and PolyPhen‑2. The functional characteristics of the PITX2c mutation were assayed using a dual‑luciferase reporter assay system. Based on the results, a novel heterozygous PITX2c mutation (p.T97A) was identified in a patient with AF. The missense mutation was absent in the 400 reference chromosomes and was automatically predicted to be disease‑causing. Multiple alignments of PITX2c protein sequences across species revealed that the altered amino acid was completely conserved evolutionarily. Functional analysis demonstrated that the mutant PITX2c protein was associated with significantly decreased transcriptional activity when compared with its wild‑type counterpart. The findings of the present study firstly link the PITX2c loss‑of‑function mutation to lone AF, and provide novel insight into the molecular mechanisms underlying AF, suggesting the potential implications for the early prophylaxis and allele‑specific therapy of this common type of arrhythmia.
Collapse
Affiliation(s)
- Yi-Meng Zhou
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Shandong University Qilu Hospital, Jinan, Shandong 250012, PR China
| | | | | | | | | |
Collapse
|
166
|
Abstract
Proper generation and conduction of the cardiac electrical impulse is essential for the continuous coordinated contraction of the heart. Dysregulation of cardiac electrical function may lead to cardiac arrhythmias, which constitute a huge medical and social burden. Identifying the genetic factors underlying cardiac electrical activity serves the double purpose of allowing the early identification of individuals at risk for arrhythmia and discovering new potential therapeutic targets for prevention. The aim of this review is to provide an overview of the genes and genetic loci linked thus far to cardiac electrical function and arrhythmia. These genes and loci have been primarily uncovered through studies on the familial rhythm disorders and through genome-wide association studies on electrocardiographic parameters in large sets of the general population. An overview of all genes and loci with their respective effect is given.
Collapse
Affiliation(s)
- Elisabeth M Lodder
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Tel.: +31 20 5665962; Fax: +31 20 6976177;
| | | |
Collapse
|
167
|
Kao YH, Chen YC, Chung CC, Lien GS, Chen SA, Kuo CC, Chen YJ. Heart failure and angiotensin II modulate atrial Pitx2c promotor methylation. Clin Exp Pharmacol Physiol 2013; 40:379-84. [PMID: 23573917 DOI: 10.1111/1440-1681.12089] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/27/2013] [Accepted: 04/04/2013] [Indexed: 02/03/2023]
Abstract
Heart failure (HF) can increase atrial fibrillation and induce cardiac hypermethylation. The homeobox gene Pitx2c plays important roles in the genesis of atrial fibrillation and the promoter region of Pitx2c contains cytosine-phosphate-guanine islands. Therefore, epigenetic modification by hypermethylation may reduce Pitx2c expression in atrial myocytes. The aim of the present study were to evaluate whether HF can modulate DNA methylation of Pitx2c and the potential mechanisms involved. We used real-time polymerase chain reaction, immunoblotting and pyrosequencing to investigate RNA and protein expression, as well as the methylation of Pitx2c, in isoproterenol-induced HF, healthy rat left atria and in HL-1 cells with and without (control) exposure to angiotensin (Ang) II (0.1 and 1 μmol/L) or isoproterenol (1 or 10 μmol/L) for 24 h. The HF atrium exhibited increased Pitx2c promoter methylation with increased DNA methyltransferase (DNMT) 1 and decreased Pitx2c protein levels compared with the normal atrium. Angiotensin II (0.1 and 1 μmol/L), increased Pitx2c promoter methylation in HL-1 cells with increased DNMT1 and decreased Pitx2c and Kir2.1 protein levels compared with control cells. These effects were attenuated by the methylation inhibitor 5-aza-2'-deoxycytidine (0.1 μmol/L) and by the AngII receptor blocker losartan (10 μmol/L). However, isoproterenol (1 and 10 μmol/L) did not change the expression of the Pitx2c, DNMT1 and Kir2.1 proteins. In conclusion, HF induces Pitx2c promoter hypermethylation and AngII may contribute to the hypermethylation in HF.
Collapse
Affiliation(s)
- Yu-Hsun Kao
- Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | | | | | | | | | | | | |
Collapse
|
168
|
Abstract
Atrial fibrillation (AF) is the most-common sustained arrhythmia observed in clinical practice, but response to therapy is highly variable between patients. Current drug therapies to suppress AF are incompletely and unpredictably effective and carry substantial risk of proarrhythmia and noncardiac toxicities. The limited success of therapy for AF is partially the result of heterogeneity of the underlying substrate, interindividual differences in disease mechanisms, and our inability to predict response to therapies in individual patients. In this Review, we discuss the evidence that variability in response to drug therapy is also conditioned by the underlying genetic substrate for AF. Increased susceptibility to AF is mediated through diverse genetic mechanisms, including modulation of the atrial action-potential duration, conduction slowing, and impaired cell-to-cell communication, as well as novel mechanisms, such as regulation of signalling proteins important in the pathogenesis of AF. However, the translation of genetic data to the care of the patients with AF has been limited because of poor understanding of the underlying mechanisms associated with common AF-susceptibility loci, a dearth of prospective, adequately powered studies, and the challenges associated with determining efficacy of antiarrhythmic drugs. What is apparent, however, is the need for appropriately designed, genotype-directed clinical trials.
Collapse
Affiliation(s)
- Dawood Darbar
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine, 2215B Garland Avenue, Nashville, TN 37323-6602, USA.
| | | |
Collapse
|
169
|
Parvez B, Shoemaker MB, Muhammad R, Richardson R, Jiang L, Blair MA, Roden DM, Darbar D. Common genetic polymorphism at 4q25 locus predicts atrial fibrillation recurrence after successful cardioversion. Heart Rhythm 2013; 10:849-55. [PMID: 23428961 PMCID: PMC3690553 DOI: 10.1016/j.hrthm.2013.02.018] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Indexed: 01/08/2023]
Abstract
BACKGROUND Genome-wide association studies have identified numerous common polymorphisms associated with atrial fibrillation (AF). The 3 loci most strongly associated with AF occur at chromosome 4q25 (near PITX2), 16q22 (in ZFHX3), and 1q21 (in KCNN3). OBJECTIVE To evaluate whether timing of AF recurrence after direct current cardioversion (DCCV) is modulated by common AF susceptibility alleles. METHODS A total of 208 patients (age 65 ± 11 years; 77% men) with persistent AF underwent successful DCCV and were prospectively evaluated at 3, 6, and 12 months for AF recurrence. Four single nucleotide polymorphisms--rs2200733 and rs10033464 at 4q25, rs7193343 in ZFHX3, and rs13376333 in KCNN3--were genotyped. RESULTS The final study cohort consisted of 184 patients. In 162 (88%) patients, sinus rhythm was restored with DCCV, of which 108 (67%) had AF recurrence at a median of 60 (interquartile range 29-176) days. In multivariable analysis, the presence of any common single nucleotide polymorphism (rs2200733, rs10033464) at the 4q25 locus was an independent predictor of AF recurrence (hazard ratio 2.1; 95% confidence interval 1.21-3.30; P = .008). Furthermore, rs2200733 exhibited a graded allelic dose response for early AF recurrence (homozygous variants: 7 [interquartile range 4-56] days; heterozygous variants: 54 [28-135] days; and wild type: 64 [29-180] days; P = .03). CONCLUSIONS To our knowledge, this is the first study to evaluate whether genomic markers can predict timing of AF recurrence in patients undergoing elective DCCV. Our findings show that a common polymorphism on chromosome 4q25 (rs2200733) is an independent predictor of AF recurrence after DCCV and point to a potential role of stratification by genotype.
Collapse
Affiliation(s)
- Babar Parvez
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37323- 6602, USA
| | | | | | | | | | | | | | | |
Collapse
|
170
|
de la Rosa AJ, Domínguez JN, Sedmera D, Sankova B, Hove-Madsen L, Franco D, Aránega AE. Functional suppression of Kcnq1 leads to early sodium channel remodelling and cardiac conduction system dysmorphogenesis. Cardiovasc Res 2013; 98:504-14. [PMID: 23542581 DOI: 10.1093/cvr/cvt076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Ion channel remodelling and ventricular conduction system (VCS) alterations play relevant roles in the generation of cardiac arrhythmias, but the interaction between ion channel remodelling and cardiac conduction system dysfunctions in an arrhythmogenic context remain unexplored. METHODS AND RESULTS We have used a transgenic mouse line previously characterized as an animal model of Long QT Syndrome (LQTS) to analyse ion channel remodelling and VCS configuration. Reverse transcriptase-PCR and immunohistochemistry analysis showed early cardiac sodium channel upregulation at embryonic stages prior to the onset of Kv potassium channel remodelling, and cardiac hypertrophy at foetal stages. In line with these findings, patch-clamp assays demonstrated changes in sodium current density and a slowing of recovery from inactivation. Functional analysis by optical mapping revealed an immature ventricular activation pattern as well as an increase in the total left ventricle activation time in foetal transgenic hearts. Morphological analysis of LQTS transgenic mice in a Cx40(GFP/+)background demonstrated VCS dysmorphogenesis during heart development. CONCLUSIONS Our data demonstrate early sodium channel remodelling secondary to IKs blockage in a mouse model of LQTS leading to morphological and functional anomalies in the developing VCS and cardiac hypertrophy. These results provide new insights into the mechanisms underlying foetal and neonatal cardiac electrophysiological disorders, which might help understand how molecular, functional, and morphological alterations are linked to clinical pathologies such as cardiac congenital anomalies, arrhythmias, and perinatal sudden death.
Collapse
Affiliation(s)
- Angel J de la Rosa
- Department of Experimental Biology, Faculty of Experimental Sciences, University of Jaén, Paraje de Lagunillas, s/n, Jaén 23071, Spain
| | | | | | | | | | | | | |
Collapse
|
171
|
Voigt N, Dobrev D. The biology of human pulmonary veins: Does it help us to better understand AF pathophysiology in patients? Heart Rhythm 2013; 10:392-3. [DOI: 10.1016/j.hrthm.2012.12.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Indexed: 02/06/2023]
|
172
|
|
173
|
Lubitz SA, Rienstra M. Genetic susceptibility to atrial fibrillation: does heart failure change our perspective? Eur J Heart Fail 2013; 15:244-6. [PMID: 23315103 DOI: 10.1093/eurjhf/hft005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
174
|
Waite MR, Skidmore JM, Micucci JA, Shiratori H, Hamada H, Martin JF, Martin DM. Pleiotropic and isoform-specific functions for Pitx2 in superior colliculus and hypothalamic neuronal development. Mol Cell Neurosci 2013; 52:128-39. [PMID: 23147109 PMCID: PMC3540135 DOI: 10.1016/j.mcn.2012.11.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 10/01/2012] [Accepted: 11/02/2012] [Indexed: 02/01/2023] Open
Abstract
Transcriptional regulation of gene expression during development is critical for proper neuronal differentiation and migration. Alternative splicing and differential isoform expression have been demonstrated for most mammalian genes, but their specific contributions to gene function are not well understood. In mice, the transcription factor gene Pitx2 is expressed as three different isoforms (PITX2A, PITX2B, and PITX2C) which have unique amino termini and common DNA binding homeodomains and carboxyl termini. The specific roles of these isoforms in neuronal development are not known. Here we report the onset of Pitx2ab and Pitx2c isoform-specific expression by E9.5 in the developing mouse brain. Using isoform-specific Pitx2 deletion mouse strains, we show that collicular neuron migration requires PITX2AB and that collicular GABAergic differentiation and targeting of hypothalamic projections require unique Pitx2 isoform dosage. These results provide insights into Pitx2 dosage and isoform-specific requirements underlying midbrain and hypothalamic development.
Collapse
Affiliation(s)
- Mindy R Waite
- Cellular and Molecular Biology Graduate Program, 2966 Taubman Medical Library, University of Michigan, Ann Arbor, MI 48109-0619, USA.
| | | | | | | | | | | | | |
Collapse
|
175
|
Mohanty S, Santangeli P, Bai R, Di Biase L, Mohanty P, Pump A, Natale A. Variant rs2200733 on chromosome 4q25 confers increased risk of atrial fibrillation: evidence from a meta-analysis. J Cardiovasc Electrophysiol 2012; 24:155-61. [PMID: 23130627 DOI: 10.1111/jce.12017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Several genome-wide association studies have identified rs2200733, a single-nucleotide polymorphism (SNP) at 4q25 to be the most common chromosomal variant present in patients with atrial fibrillation (AF). We aimed to explore the association of rs2200733 with AF through a systematic review and meta-analysis. METHOD An extensive literature search was performed on PubMed, and other databases using the key words "genetics" and "AF." Seven case-control studies evaluating the association via multivariate analysis were identified including a total of 83,335 subjects (10,546 with AF, 72,789 referent individuals without AF). Meta-analytic estimates were derived using random effects models. Potential sources of heterogeneity were examined in sensitivity analyses, and publication biases were estimated. RESULT At pooled analysis, there was a strong independent association between the variant rs2200733 and the risk of AF (OR 1.89 [95% CI 1.62-2.16], P < 0.001). Minor allelic frequencies for SNP rs22000733 were significantly more prevalent in AF population than non-AF. Metaregression results revealed that country of descent (logOR 0.38, P = 0.45) or site of study (logOR: -0.16, P = 0.41) did not moderate the overall effect size. CONCLUSION Variant rs2200733 on chromosome 4q25 independently confers increased risk of AF. This finding will aid in improving our understanding of AF pathophysiology, risk prediction, and stratification of treatment strategy.
Collapse
Affiliation(s)
- Sanghamitra Mohanty
- St. David's Medical Center, Texas Cardiac Arrhythmia Institute, Austin, Texas 78705, USA
| | | | | | | | | | | | | |
Collapse
|
176
|
Abstract
During the past few years, the development of effective, empirical technologies for treatment of cardiac arrhythmias has exceeded the pace at which detailed knowledge of the underlying biology has accumulated. As a result, although some clinical arrhythmias can be cured with techniques such as catheter ablation, drug treatment and prediction of the risk of sudden death remain fairly primitive. The identification of key candidate genes for monogenic arrhythmia syndromes shows that to bring basic biology to the clinic is a powerful approach. Increasingly sophisticated experimental models and methods of measurement, including stem cell-based models of human cardiac arrhythmias, are being deployed to study how perturbations in several biologic pathways can result in an arrhythmia-prone heart. The biology of arrhythmia is largely quantifiable, which allows for systematic analysis that could transform treatment strategies that are often still empirical into management based on molecular evidence.
Collapse
Affiliation(s)
- Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
| | | |
Collapse
|
177
|
Abstract
Over the past decade, compelling evidence has emerged from population-based studies to suggest that AF is a heritable disease. More recently, we have begun to elucidate the genetic substrate underlying AF. Genome-wide association studies (GWAS) have led to the identification of multiple risk loci that confer increased susceptibility to the arrhythmia. These loci harbor intriguing candidate genes including those encoding ion channels, transcription factors, and signaling molecules. Current efforts are ongoing to functionally validate the role of these genes in disease pathogenesis. In the future, novel genotyping technologies such as exome sequencing and whole-genome sequencing promise to uncover a greater proportion of the heritability underlying AF. In this article we review recent advances in AF genetics research and discuss future developments in the field.
Collapse
Affiliation(s)
- Saagar Mahida
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, USA
| | | |
Collapse
|
178
|
Riley G, Syeda F, Kirchhof P, Fabritz L. An introduction to murine models of atrial fibrillation. Front Physiol 2012; 3:296. [PMID: 22934047 PMCID: PMC3429067 DOI: 10.3389/fphys.2012.00296] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 07/08/2012] [Indexed: 01/28/2023] Open
Abstract
Understanding the mechanism of re-entrant arrhythmias in the past 30 years has allowed the development of almost curative therapies for many rhythm disturbances. The complex, polymorphic arrhythmias of atrial fibrillation (AF) and sudden death are, unfortunately, not yet well understood, and hence still in need of adequate therapy. AF contributes markedly to morbidity and mortality in aging Western populations. In the past decade, many genetically altered murine models have been described and characterized. Here, we review genetically altered murine models of AF; powerful tools that will enable a better understanding of the mechanisms of AF and the assessment of novel therapeutic interventions.
Collapse
Affiliation(s)
- Genna Riley
- Centre for Cardiovascular Sciences, School of Clinical and Experimental Medicine, University of Birmingham Birmingham, UK
| | | | | | | |
Collapse
|
179
|
Rienstra M, McManus DD, Benjamin EJ. Novel risk factors for atrial fibrillation: useful for risk prediction and clinical decision making? Circulation 2012; 125:e941-6. [PMID: 22615425 DOI: 10.1161/circulationaha.112.112920] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Michiel Rienstra
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9700 RB Groningen, The Netherlands.
| | | | | |
Collapse
|
180
|
Common genetic variants associated with sudden cardiac death: the FinSCDgen study. PLoS One 2012; 7:e41675. [PMID: 22844511 PMCID: PMC3402479 DOI: 10.1371/journal.pone.0041675] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 06/24/2012] [Indexed: 12/02/2022] Open
Abstract
Background Sudden cardiac death (SCD) accounts for up to half of cardiac mortality. The risk of SCD is heritable but the underlying genetic variants are largely unknown. We investigated whether common genetic variants predisposing to arrhythmia or related electrocardiographic phenotypes, including QT-interval prolongation, are associated with increased risk of SCD. Methodology/Principal Findings We studied the association between 28 candidate SNPs and SCD in a meta-analysis of four population cohorts (FINRISK 1992, 1997, 2002 and Health 2000, n = 27,629) and two forensic autopsy series (The Helsinki Sudden Death Study and The Tampere Autopsy Study, n = 694). We also studied the association between established cardiovascular risk factors and SCD. Causes of death were reviewed using registry-based health and autopsy data. Cox regression and logistic regression models were adjusted for age, sex, and geographic region. The total number of SCDs was 716. Two novel SNPs were associated with SCD: SCN5A rs41312391 (relative risk [RR] 1.27 per minor T allele, 95% CI 1.11–1.45, P = 3.4×10−4) and rs2200733 in 4q25 (RR 1.28 per minor T allele, 95% CI 1.11–1.48, P = 7.9×10−4). We also replicated the associations for 9p21 (rs2383207, RR 1.13 per G allele, 95% CI 1.01–1.26, P = 0.036), as well as for male sex, systolic blood pressure, diabetes, cigarette smoking, low physical activity, coronary heart disease, and digoxin use (P<0.05). Conclusions/Significance Two novel genetic variants, one in the cardiac sodium channel gene SCN5A and another at 4q25 previously associated with atrial fibrillation, are associated with SCD.
Collapse
|
181
|
Is altered atrial microRNA-ome a critical contributor to the pathophysiology of atrial fibrillation? Basic Res Cardiol 2012; 107:284. [DOI: 10.1007/s00395-012-0284-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 07/04/2012] [Indexed: 12/11/2022]
|
182
|
Normal and abnormal development of the cardiac conduction system; implications for conduction and rhythm disorders in the child and adult. Differentiation 2012; 84:131-48. [DOI: 10.1016/j.diff.2012.04.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 04/16/2012] [Indexed: 11/20/2022]
|
183
|
Parvez B, Vaglio J, Rowan S, Muhammad R, Kucera G, Stubblefield T, Carter S, Roden D, Darbar D. Symptomatic response to antiarrhythmic drug therapy is modulated by a common single nucleotide polymorphism in atrial fibrillation. J Am Coll Cardiol 2012; 60:539-45. [PMID: 22726630 DOI: 10.1016/j.jacc.2012.01.070] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 01/13/2012] [Accepted: 01/17/2012] [Indexed: 12/19/2022]
Abstract
OBJECTIVES This study tested the hypothesis that response to antiarrhythmic drugs (AADs) is modulated by 3 common loci associated with atrial fibrillation (AF). BACKGROUND Recent genome-wide association studies have identified 3 loci, on chromosomes 4q25 (near PITX2), 16q22 (in ZFHX3), and 1q21 (in KCNN3), that associate with either typical or lone AF. These findings indicate that variable mechanisms contribute to AF susceptibility, and suggest that response to therapy may be genotype dependent. METHODS We studied 478 and 198 Caucasian patients in the discovery cohort and validation cohort, respectively, who were prospectively enrolled in the Vanderbilt AF registry. Response was defined prospectively as successful rhythm control if the patient remained on the same AAD therapy for a minimum of 6 months with ≥75% reduction in symptomatic AF burden. We also evaluated AF recurrence by 12-lead electrocardiogram (ECG) at 3, 6, and 12 months. Symptomatic patients were also given a 24- to 48-h Holter monitor or 30-day event recorder when AF recurrence was not captured by 12-lead ECG. RESULTS In the discovery cohort, 399 (83%) patients were successfully rhythm controlled. Multiple clinical variables (including age, hypertension, lone AF) failed to significantly predict response to AADs; however, single nucleotide polymorphism (SNP) rs10033464 at 4q25 was an independent predictor of successful rhythm control in patients with typical AF carrying the ancestral allele (wild type) versus carriers of variant allele (odds ratio [OR]: 4.7, 95% confidence interval [CI]: 1.83 to 12, p = 0.0013. In the validation cohort, 143 (72%) patients met the criteria for successful rhythm control, and rs10033464 was again an independent predictor of successful rhythm control, OR: 1.5, 95% CI: 1.02 to 3.06, p = 0.04. This SNP (rs10033464) was an independent predictor of AF recurrence in the discovery (39% AF recurrence) and validation (38% AF recurrence) cohorts; OR: 3.27, 95% CI: 1.7 to 6, p < 0.001 and OR: 4.3, 95% CI: 1.98 to 9.4, p < 0.001, respectively. CONCLUSIONS These results suggest that a common SNP on chromosome 4q25 associated with AF modulates response to AAD therapy and points to a potential role for stratification of therapeutic approaches by genotype.
Collapse
Affiliation(s)
- Babar Parvez
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37323-6602, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
184
|
Franco D, Chinchilla A, Aránega AE. Transgenic insights linking pitx2 and atrial arrhythmias. Front Physiol 2012; 3:206. [PMID: 22701438 PMCID: PMC3372893 DOI: 10.3389/fphys.2012.00206] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Accepted: 05/23/2012] [Indexed: 12/19/2022] Open
Abstract
Pitx2 is a homeobox transcription factor involved in left–right signaling during embryogenesis. Disruption of left–right signaling in mice within its core nodal/lefty cascade, results in impaired expression of the last effector of the left–right cascade, Pitx2, leading in many cases to absence or bilateral expression of Pitx2 in lateral plate mesoderm (LPM). Loss of Pitx2 expression in LPM results in severe cardiac malformations, including right cardiac isomerism. Pitx2 is firstly expressed asymmetrically in the left but not right LPM, before the cardiac crescent forms, and subsequently, as the heart develops, becomes confined to the left side of the linear heart tube. Expression of Pitx2 is remodeled during cardiac looping, becoming localized to the ventral portion of the developing ventricular chambers, while maintaining a distinct left-sided atrial expression. The importance of Pitx2 during cardiogenesis has been illustrated by the complex and robust cardiac defects observed on systemic deletion of Pitx2 in mice. Lack of Pitx2 expression leads to embryonic lethality at mid-term, and Pitx2-deficient embryos display isomeric hearts with incomplete closure of the body wall. However, whereas the pivotal role of Pitx2 during cardiogenesis is well sustained, its putative role in the fetal and adult heart is largely unexplored. Recent genome-wide association studies have identified several genetic variants highly associated with atrial fibrillation (AF). Among them are genetic variants located on chromosome 4q25 adjacent to PITX2. Since then several transgenic approaches have provided evidences of the role of the homeobox transcription factor PITX2 and atrial arrhythmias. Here, we review new insights into the cellular and molecular links between PITX2 and AF.
Collapse
Affiliation(s)
- Diego Franco
- Department of Experimental Biology, University of Jaen Jaen, Spain
| | | | | |
Collapse
|
185
|
Hsu J, Hanna P, Van Wagoner DR, Barnard J, Serre D, Chung MK, Smith JD. Whole genome expression differences in human left and right atria ascertained by RNA sequencing. ACTA ACUST UNITED AC 2012; 5:327-35. [PMID: 22474228 DOI: 10.1161/circgenetics.111.961631] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND The left and right atria have different susceptibilities toward developing arrhythmias, with left atrial arrhythmias more commonly observed. To understand the molecular basis for such differences, we catalogued micro (mi)RNA and mRNA expression differences by next generation sequencing. METHODS AND RESULTS Four human left-right atrial pairs were subjected to whole-genome expression analyses via next-generation sequencing of small RNAs, including miRNAs, and poly-A-enriched mRNAs. Using a paired sample design, significant differences in the expression of 32 miRNAs were found in between the left and right atria at a probability value of <0.01. Hsa-miR-143 was the most highly expressed miRNA in the atria, as quantified by RNA sequencing. There were 746 and 2292 differentially expressed mRNAs between the left and right atria at false discovery rates of <0.001 and <0.05, respectively. Transcription factor binding elements within 2 kb of RefSeq genes were determined and specific motifs were identified that were enriched in differentially expressed genes. Similarly, specific miRNA target sequences in 3' UTRs were also enriched in differentially expressed genes. In addition, 11 novel noncoding RNAs of unknown function were found to be differentially expressed between the left and right atria. CONCLUSIONS There are significant differences in miRNA and mRNA expression profiles between the left and right atria, which may yield insight into increased the arrhythmogenesis of the left atria.
Collapse
Affiliation(s)
- Jeffrey Hsu
- Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, OH, USA
| | | | | | | | | | | | | |
Collapse
|
186
|
Olesen MS, Holst AG, Jabbari J, Nielsen JB, Christophersen IE, Sajadieh A, Haunsø S, Svendsen JH. Genetic loci on chromosomes 4q25, 7p31, and 12p12 are associated with onset of lone atrial fibrillation before the age of 40 years. Can J Cardiol 2012; 28:191-5. [PMID: 22336519 DOI: 10.1016/j.cjca.2011.11.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Revised: 11/25/2011] [Accepted: 11/25/2011] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Three distinct genetic loci on chromosomes 1q21, 4q25, and 16q22 have been associated with atrial fibrillation (AF) in genome-wide association studies (GWAS). Five additional loci have been associated primarily with the PR interval and subsequently with AF. We aimed to investigate if 8 single nucleotide polymorphisms (SNPs), representing the 8 genomic loci previously linked with AF in genome-wide association studies, were associated with early-onset lone AF. METHODS We included 209 patients with early-onset lone AF, and a control group consisting of 534 individuals free of AF. The 8 SNPs were genotyped using TaqMan assays (Applied Biosystems, Foster City, CA). RESULTS Three SNPs were found to be significantly associated with early-onset lone AF: rs2200733 closest to PITX2 (odds ratio [OR], 1.62; 95% confidence interval [CI], 1.16-2.27; P = 0.004), rs3807989 near to CAV1 (OR 1.35; 95% CI, 1.06-1.72; P = 0.015), and rs11047543 near to SOX5 (OR 1.70; 95% CI, 1.18-2.44; P = 0.004). When correcting for multiple testing, rs2200733 and rs11047543 were still significantly associated with AF. CONCLUSIONS Three SNPs, rs2200733 (4q25), rs3807989 (7p31), and rs11047543 (12p12), were associated with early-onset lone AF. All 3 SNPs are positioned close to genes that in previous studies have been demonstrated to be important for cardiac morphology/development, thereby suggesting a link between these SNPs and structural heart disease. Our results however, indicate that variants in these 3 loci are associated with AF through mechanisms that do not involve major structural abnormalities in the heart.
Collapse
Affiliation(s)
- Morten S Olesen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia, Copenhagen, Denmark.
| | | | | | | | | | | | | | | |
Collapse
|
187
|
Circulation: Arrhythmia and Electrophysiology
Editors' Picks. Circ Arrhythm Electrophysiol 2012. [DOI: 10.1161/circep.112.970889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The following articles are being highlighted as part of
Circulation: Arrhythmia and Electrophysiology's
Topic Review series. This series will summarize the most important articles, as selected by the editors, published in
Circulation: Arrhythmia and Electrophysiology, Circulation,
and the other
Circulation
subspecialty journals. The studies included in this article represent the most read articles published on the topic of bradyarrhythmias in 2010 and 2011.
Collapse
|
188
|
Ammirabile G, Tessari A, Pignataro V, Szumska D, Sutera Sardo F, Benes J, Balistreri M, Bhattacharya S, Sedmera D, Campione M. Pitx2 confers left morphological, molecular, and functional identity to the sinus venosus myocardium. Cardiovasc Res 2012; 93:291-301. [PMID: 22116619 PMCID: PMC3258653 DOI: 10.1093/cvr/cvr314] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 11/16/2011] [Accepted: 11/18/2011] [Indexed: 11/12/2022] Open
Abstract
AIMS The sinus venous myocardium, comprising the sinoatrial node (SAN) and sinus horns (SH), is a region subject to congenital malformations and cardiac arrhythmias. It differentiates from symmetric bilateral mesenchymal precursors, but morphological, molecular, and functional left/right differences are progressively established through development. The role of the laterality gene Pitx2 in this process is unknown. We aimed to elucidate the molecular events driving left/right patterning in the sinus venosus (SV) myocardium by using a myocardial Pitx2 knockout mouse. METHODS AND RESULTS We generated a myocardial specific Pitx2 knockout model (cTP mice). cTP embryos present several features of Pitx2 null, including right atrial isomerism with bilateral SANs and symmetric atrial entrance of the systemic veins. By in situ hybridization and optical mapping analysis, we compared throughout development the molecular and functional properties of the SV myocardium in wt and mutant embryos. We observed that Pitx2 prevents the expansion of the left-SAN primordium at the onset of its differentiation into myocardium; Pitx2 promotes expansion of the left SH through development; Pitx2 dose-dependently represses the autorhythmic properties of the left SV myocardium at mid-gestation (E14.5); Pitx2 modulates late foetal gene expression at the left SH-derived superior caval vein. CONCLUSION Pitx2 drives left/right patterning of the SV myocardium through multiple developmental steps. Overall, Pitx2 plays a crucial functional role by negatively modulating a nodal-type programme in the left SV myocardium.
Collapse
Affiliation(s)
- Grazia Ammirabile
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Alessandra Tessari
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Viviana Pignataro
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Dorota Szumska
- Department of Cardiovascular Medicine, Wellcome Trust Center for Human Genetics, Oxford, UK
| | - Fabio Sutera Sardo
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Jiri Benes
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague,Czech Republic
| | - Mariangela Balistreri
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| | - Shoumo Bhattacharya
- Department of Cardiovascular Medicine, Wellcome Trust Center for Human Genetics, Oxford, UK
| | - David Sedmera
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic
- Institute of Anatomy, First Faculty of Medicine, Charles University, Prague,Czech Republic
| | - Marina Campione
- CNR Institute of Neurosciences, Department of Biomedical Sciences, University of Padova, Viale G. Colombo 3, Padova 35121, Italy
| |
Collapse
|
189
|
Liu X, Wang F, Knight AC, Zhao J, Xiao J. Common variants for atrial fibrillation: results from genome-wide association studies. Hum Genet 2011; 131:33-9. [DOI: 10.1007/s00439-011-1052-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 06/20/2011] [Indexed: 12/19/2022]
|