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Double or compound sarcomere mutations in hypertrophic cardiomyopathy: a potential link to sudden death in the absence of conventional risk factors. Heart Rhythm 2011; 9:57-63. [PMID: 21839045 DOI: 10.1016/j.hrthm.2011.08.009] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 08/04/2011] [Indexed: 01/18/2023]
Abstract
BACKGROUND Risk stratification strategies employing sarcomere gene mutational analysis have proved imprecise in identifying high-risk patients with hypertrophic cardiomyopathy (HCM). Therefore, additional genetic risk markers that reliably determine which patients are predisposed to sudden death are needed. OBJECTIVE The objective of this study was to determine whether multiple disease-causing sarcomere mutations can be regarded as markers for sudden death in the absence of other conventional risk factors. METHODS Databases of 3 HCM centers were accessed, and 18 probands with 2 disease-causing mutations in genes encoding proteins of the cardiac sarcomere were identified. RESULTS Severe disease progression or adverse cardiovascular events occurred in 7 of these 18 patients (39%), including 3 patients (ages 31, 37, and 57 years) who experienced sudden cardiac arrest but also were without evidence of conventional HCM risk factors; 2 survived with timely defibrillation and therapeutic hypothermia and 1 died. These 3 probands carried distinct and heterozygous disease-causing sarcomere mutations (including a man who inherited 1 mutation independently from each of his parents with HCM)-that is, double MYBPC3 and TNNI3 mutations and compound MYBPC3 mutations-as the only predisposing clinical markers evident to potentially explain their unexpected cardiac event. CONCLUSIONS These observations support the emerging hypothesis that double (or compound) mutations detected by genetic testing may confer a gene dosage effect in HCM, thereby predisposing patients to adverse disease progression. In 3 families, multiple sarcomere mutations were associated with a risk of sudden death, even in the absence of conventional risk factors.
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Abstract
During the past two decades, numerous disease-causing genes for different cardiomyopathies have been identified. These discoveries have led to better understanding of disease pathogenesis and initial steps in the application of mutation analysis in the evaluation of affected individuals and their family members. As knowledge of the genetic abnormalities, and insight into cellular and organ biology has grown, so has appreciation of the level of complexity of interaction between genotype and phenotype across disease states. What were initially thought to be one-to-one gene-disease correlates have turned out to display important relational plasticity dependent in large part on the genetic and environmental backgrounds into which the genes of interest express. The current state of knowledge with regard to genetics of cardiomyopathy represents a starting point to address the biology of disease, but is not yet developed sufficiently to supplant clinically based classification systems or, in most cases, to guide therapy to any significant extent. Future work will of necessity be directed towards elucidation of the biological mechanisms of both rare and common gene variants and environmental determinants of plasticity in the genotype-phenotype relationship with the ultimate goal of furthering our ability to identify, diagnose, risk stratify, and treat this group of disorders which cause heart failure and sudden death in the young.
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Affiliation(s)
- Daniel Jacoby
- Division of Cardiology, Yale School of Medicine, New Haven, CT 06519, USA
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53
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Christiaans I, Nannenberg EA, Dooijes D, Jongbloed RJE, Michels M, Postema PG, Majoor-Krakauer D, van den Wijngaard A, Mannens MMAM, van Tintelen JP, van Langen IM, Wilde AAM. Founder mutations in hypertrophic cardiomyopathy patients in the Netherlands. Neth Heart J 2011; 18:248-54. [PMID: 20505798 DOI: 10.1007/bf03091771] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In this part of a series on cardiogenetic founder mutations in the Netherlands, we review the Dutch founder mutations in hypertrophic cardiomyopathy (HCM) patients. HCM is a common autosomal dominant genetic disease affecting at least one in 500 persons in the general population. Worldwide, most mutations in HCM patients are identified in genes encoding sarcomeric proteins, mainly in the myosin-binding protein C gene (MYBPC3, OMIM #600958) and the beta myosin heavy chain gene (MYH7, OMIM #160760). In the Netherlands, the great majority of mutations occur in the MYBPC3, involving mainly three Dutch founder mutations in the MYBPC3 gene, the c.2373_2374insG, the c.2864_2865delCT and the c.2827C>T mutation. In this review, we describe the genetics of HCM, the genotype-phenotype relation of Dutch founder MYBPC3 gene mutations, the prevalence and the geographic distribution of the Dutch founder mutations, and the consequences for genetic counselling and testing. (Neth Heart J 2010;18:248-54.).
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Affiliation(s)
- I Christiaans
- Department of Clinical Genetics, Academic Medical Centre, Amsterdam, the Netherlands These authors contributed equally
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54
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Tanjore R, Rangaraju A, Vadapalli S, Remersu S, Narsimhan C, Nallari P. Genetic variations of β-MYH7 in hypertrophic cardiomyopathy and dilated cardiomyopathy. INDIAN JOURNAL OF HUMAN GENETICS 2011; 16:67-71. [PMID: 21031054 PMCID: PMC2955954 DOI: 10.4103/0971-6866.69348] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
CONTEXT: Hypertrophic cardiomyopathy (HCM) is known to be manifested by mutations in 12 sarcomeric genes and dilated cardiomyopathy (DCM) is known to manifest due to cytoskeletal mutations. Studies have revealed that sarcomeric mutations can also lead to DCM. Therefore, in the present study, we have made an attempt to compare and analyze the genetic variations of beta-myosin heavy chain gene (β-MYH7), which are interestingly found to be common in both HCM and DCM. The underlying pathophysiological mechanism leading to two different phenotypes has been discussed in this study. Till date, about 186 and 73 different mutations have been reported in HCM and DCM, respectively, with respect to this gene. AIM: The screening of β-MYH7 gene in both HCM and DCM has revealed some common genetic variations. The aim of the present study is to understand the pathophysiological mechanism underlying the manifestation of two different phenotypes. MATERIALS AND METHODS: 100 controls, 95 HCM and 97 DCM samples were collected. Genomic DNA was extracted following rapid nonenzymatic method as described by Lahiri and Nurnberger (1991), and the extracted DNA was later subjected to polymerase chain reaction (PCR) based single stranded conformation polymorphism (SSCP) analysis to identify single nucleotide polymorphism (SNP)s/mutations associated with the diseased phenotypes. RESULTS AND CONCLUSION: Similar variations were observed in β-MYH7 exons 7, 12, 19 and 20 in both HCM and DCM. This could be attributed to impaired energy compromise, or to dose effect of the mutant protein, or to even environmental factors/modifier gene effects wherein an HCM could progress to a DCM phenotype affecting both right and left ventricles, leading to heart failure.
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Affiliation(s)
- Reena Tanjore
- Department of Genetics, Osmania University, Jamai Osmania P.O., Hyderabad-500 007, India
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55
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Abstract
Sixteen years ago, mutations in cardiac troponin (Tn)T and α-tropomyosin were linked to familial hypertrophic cardiomyopathy, thus transforming the disorder from a disease of the β-myosin heavy chain to a disease of the cardiac sarcomere. From the outset, studies suggested that mutations in the regulatory thin filament caused a complex, heterogeneous pattern of ventricular remodeling with wide variations in clinical expression. To date, the clinical heterogeneity is well matched by an extensive array of nearly 100 independent mutations in all components of the cardiac thin filament. Significant advances in our understanding of the biophysics of myofilament activation, coupled to the emerging evidence that thin filament linked cardiomyopathies are progressive, suggests that a renewed focus on the most proximal events in both the molecular and clinical pathogenesis of the disease will be necessary to achieve the central goal of using genotype information to manage affected patients. In this review, we examine the existing biophysical and clinical evidence in support of a more proximal definition of thin filament cardiomyopathies. In addition, new high-resolution, integrated approaches are presented to help define the way forward as the field works toward developing a more robust link between genotype and phenotype in this complex disorder.
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Affiliation(s)
- Jil C Tardiff
- Department of Physiology and Biophysics, Department of Internal Medicine, Division of Adult Cardiology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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56
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Kim L, Devereux RB, Basson CT. Impact of genetic insights into mendelian disease on cardiovascular clinical practice. Circulation 2011; 123:544-50. [PMID: 21300962 DOI: 10.1161/circulationaha.109.914804] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Luke Kim
- Greenberg Division of Cardiology, Weill Medical College of Cornell University, New York Presbyterian Hospital–Cornell Medical Center, New York, NY, USA
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57
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Tester DJ, Ackerman MJ. Genetic testing for potentially lethal, highly treatable inherited cardiomyopathies/channelopathies in clinical practice. Circulation 2011; 123:1021-37. [PMID: 21382904 PMCID: PMC3073829 DOI: 10.1161/circulationaha.109.914838] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- David J Tester
- Long QT Syndrome Clinic and the Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
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58
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Chang B, Nishizawa T, Furutani M, Fujiki A, Tani M, Kawaguchi M, Ibuki K, Hirono K, Taneichi H, Uese K, Onuma Y, Bowles NE, Ichida F, Inoue H, Matsuoka R, Miyawaki T. Identification of a novel TPM1 mutation in a family with left ventricular noncompaction and sudden death. Mol Genet Metab 2011; 102:200-6. [PMID: 20965760 DOI: 10.1016/j.ymgme.2010.09.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Accepted: 09/23/2010] [Indexed: 01/12/2023]
Abstract
Left ventricular noncompaction (LVNC) is a cardiomyopathy morphologically characterized by 2-layered myocardium, numerous prominent trabeculations, and deep intertrabecular recesses communicating with the left ventricular cavity. The purpose of this study was to investigate patients with LVNC for possible disease causing mutations. We screened 4 genes (TAZ, LDB3, DTNA and TPM1) in 51 patients with LVNC for mutations by polymerase chain reaction and direct DNA sequencing. A novel missense substitution in exon 1 of TPM1 (c.109A>G: p.Lys37Glu) was identified in three affected members of a family with isolated LVNC. The substitution brings about a change in amino acid charge at a highly conserved residue and could result in aberrant mRNA splicing. This variant was not identified in 200 normal control samples. Pathologic analysis of a right ventricular myocardial specimen from the proband's maternal aunt revealed endocardial and subendocardial fibrosis with prominent elastin deposition, as well as the presence of adipose tissue between muscle layers, pathologic changes that are distinct from those seen in patients with HCM or DCM. Screening of the proband and her mother for variants in other sarcomeric protein-encoding candidate genes, MYH7, MYBPC3, TNNT2, TNNI3, ACTC, MYL2, and MYL3, did not identify any other non-synonymous variants or variants in splice donor-acceptor sequences that were potentially disease causing. We conclude TPM1 is a potential candidate disease-causing gene for isolated LVNC, especially in patients experiencing sudden death.
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Affiliation(s)
- Bo Chang
- Department of Pediatrics, University of Toyama, 2630 Sugitani, Toyama, Japan
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59
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Affiliation(s)
- Carolyn Y Ho
- Cardiovascular Genetics Center, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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60
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Landstrom AP, Ackerman MJ. Mutation type is not clinically useful in predicting prognosis in hypertrophic cardiomyopathy. Circulation 2010; 122:2441-9; discussion 2450. [PMID: 21135372 PMCID: PMC6309993 DOI: 10.1161/circulationaha.110.954446] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hypertrophic cardiomyopathy (HCM), or clinically unexplained hypertrophy of the heart, is a common genetic cardiovascular disorder marked by genetic and phenotypic heterogeneity. As the genetic mutations underlying the pathogenesis of this disease have been identified, investigators have attempted to link mutations to clearly defined alterations in survival in hopes of identifying prognostically relevant biomarkers of disease. While initial studies labeling particular MYH7 -encoded beta myosin heavy chain and TNNT2 -encoded cardiac troponin T mutations as “malignant” or “benign” raised hopes for mutation-specific risk stratification in HCM, a series of subsequent investigations identified mutations in families with contradictory disease phenotypes. Furthermore, subsequent proband-based cohort studies indicated that the clinical prognostic relevance of individual mutations labeled as “malignant” or “benign” in large referral centers is negligible. Herein, we seek to summarize the controversy and dispute the notion that mutation-specific risk stratification in HCM is possible at the present time. We provide evidence for clinicians and basic scientists alike to move beyond simple mutation descriptors to a more nuanced understanding of HCM mutations that fully captures the multi-factorial nature of HCM disease expression.
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Affiliation(s)
- Andrew P Landstrom
- Department of Medicine, Division of Cardiovascular Diseases, and the Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN 55905, USA
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61
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Khan H, Guglin M. Understanding hypertrophic cardiomyopathy: implications of diagnosis for the patient and family. Int J Clin Pract 2010; 64:1699-704. [PMID: 20412333 DOI: 10.1111/j.1742-1241.2009.02180.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) may be a challenging condition for an internist. The algorithm for work-up and treatment is fairly straight forward when the presentation is classic. However, in the real world, subtle and moderate forms of the disease occur more commonly. We analyse, step by step, diagnosis and management of a patient with mild HCM and review the literature on pertinent questions regarding diagnosis, risk stratification, treatment options and implications for patient's lifestyle and for his family.
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Affiliation(s)
- H Khan
- Heart Failure, University of South Florida, Tampa, FL 33618, USA
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62
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Millat G, Chanavat V, Créhalet H, Rousson R. Development of a high resolution melting method for the detection of genetic variations in hypertrophic cardiomyopathy. Clin Chim Acta 2010; 411:1983-91. [PMID: 20800588 DOI: 10.1016/j.cca.2010.08.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2010] [Revised: 08/10/2010] [Accepted: 08/10/2010] [Indexed: 01/09/2023]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac disease affecting 1 in 500 people. Due to large cohorts to investigate, the number of disease-causing genes, the size of the 2 prevalent mutated genes, and the presence of a large spectrum of private mutations, mutational screening must be performed using an extremely sensitive and specific scanning method. METHODS High Resolution Melting (HRM) analysis was developed for prevalent HCM-causing genes (MYBPC3, MYH7, TNNT2, and TNNI3) using control DNAs and DNAs carrying previously identified gene variants. A cohort of 34 HCM patients was further blindly screened. To evaluate HRM sensitivity, this cohort was also screened using an optimized DHPLC methodology. RESULTS All gene variants detected by DHPLC were also readily identified as abnormal by HRM analysis. Mutational screening of a cohort of 34 HCM cases led to identification of 19 mutated alleles. Complete molecular investigation was completed two times faster and cheaper than using DHPLC strategy. CONCLUSIONS HRM analysis represents an inexpensive, highly sensitive and high-throughput method to allow identification of mutations in the coding sequences of prevalent HCM genes. Identification of more HCM mutations will provide new insights into genotype/phenotype relationships and will allow a better knowledge of the HCM physiopathology.
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Affiliation(s)
- Gilles Millat
- Laboratoire de Cardiogénétique Moléculaire, Centre de Biologie et Pathologie Est, Hospices Civils de Lyon, Lyon, France.
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63
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Callis TE, Jensen BC, Weck KE, Willis MS. Evolving molecular diagnostics for familial cardiomyopathies: at the heart of it all. Expert Rev Mol Diagn 2010; 10:329-51. [PMID: 20370590 PMCID: PMC5022563 DOI: 10.1586/erm.10.13] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cardiomyopathies are an important and heterogeneous group of common cardiac diseases. An increasing number of cardiomyopathies are now recognized to have familial forms, which result from single-gene mutations that render a Mendelian inheritance pattern, including hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy and left ventricular noncompaction cardiomyopathy. Recently, clinical genetic tests for familial cardiomyopathies have become available for clinicians evaluating and treating patients with these diseases, making it necessary to understand the current progress and challenges in cardiomyopathy genetics and diagnostics. In this review, we summarize the genetic basis of selected cardiomyopathies, describe the clinical utility of genetic testing for cardiomyopathies and outline the current challenges and emerging developments.
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Affiliation(s)
- Thomas E Callis
- PGxHealth Division, Clinical Data, Inc., 5 Science Park, New Haven, CT 06511, USA
| | - Brian C Jensen
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC, 27599-7126, USA and Department of Internal Medicine, Section of Cardiology, University of North Carolina, Chapel Hill, NC 27599-7075, USA
| | - Karen E Weck
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599-7525, USA
| | - Monte S Willis
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599-7525, USA and McAllister Heart Institute, University of North Carolina at Chapel Hill, 2340B Medical Biomolecular Research Building, 103 Mason Farm Road, Chapel Hill, NC 27599-7525, USA Tel.: +1 919 843 1938 Fax: +1 919 843 4585
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64
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Harris B, Pfotenhauer JP, Silverstein CA, Markham LW, Schafer K, Exil VJ, Hong CC. Serial observations and mutational analysis of an adoptee with family history of hypertrophic cardiomyopathy. Cardiol Res Pract 2010; 2010:697269. [PMID: 20309391 PMCID: PMC2838361 DOI: 10.4061/2010/697269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Accepted: 02/01/2010] [Indexed: 11/20/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited cardiac disease with an autosomal dominant mode of transmission. Comprehensive genetic screening of several genes frequently found mutated in HCM is recommended for first-degree relatives of HCM patients. Genetic testing provides the means to identify those at risk of developing HCM and to institute measures to prevent sudden cardiac death (SCD). Here, we present an adoptee whose natural mother and maternal relatives were known be afflicted with HCM and SCD. The proband was followed closely from age 6 to 17 years, revealing a natural history of the progression of clinical findings associated with HCM. Genetic testing of the proband and her natural mother, who is affected by HCM, revealed that they were heterozygous for both the R719Q and T1513S variants in the cardiac beta-myosin heavy chain (MYH7) gene. The proband's ominous family history indicates that the combination of the R719Q and T1513S variants in cis may be a "malignant" variant that imparts a poor prognosis in terms of the disease progression and SCD risk.
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Affiliation(s)
- Bronwyn Harris
- Center for Inherited Heart Disease, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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65
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Elliott P, McKenna WJ. How should hypertrophic cardiomyopathy be classified?: Molecular diagnosis for hypertrophic cardiomyopathy: Not ready for prime time. ACTA ACUST UNITED AC 2010; 2:87-9; discussion 89. [PMID: 20031570 DOI: 10.1161/circgenetics.108.835645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Perry Elliott
- Department of Medicine, Institute of Cardiovascular Science, University College London, United Kingdom
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66
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Davis J, Metzger JM. Combinatorial effects of double cardiomyopathy mutant alleles in rodent myocytes: a predictive cellular model of myofilament dysregulation in disease. PLoS One 2010; 5:e9140. [PMID: 20161772 PMCID: PMC2818843 DOI: 10.1371/journal.pone.0009140] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Accepted: 01/19/2010] [Indexed: 12/05/2022] Open
Abstract
Inherited cardiomyopathy (CM) represents a diverse group of cardiac muscle diseases that present with a broad spectrum of symptoms ranging from benign to highly malignant. Contributing to this genetic complexity and clinical heterogeneity is the emergence of a cohort of patients that are double or compound heterozygotes who have inherited two different CM mutant alleles in the same or different sarcomeric gene. These patients typically have early disease onset with worse clinical outcomes. Little experimental attention has been directed towards elucidating the physiologic basis of double CM mutations at the cellular-molecular level. Here, dual gene transfer to isolated adult rat cardiac myocytes was used to determine the primary effects of co-expressing two different CM-linked mutant proteins on intact cardiac myocyte contractile physiology. Dual expression of two CM mutants, that alone moderately increase myofilament activation, tropomyosin mutant A63V and cardiac troponin mutant R146G, were shown to additively slow myocyte relaxation beyond either mutant studied in isolation. These results were qualitatively similar to a combination of moderate and strong activating CM mutant alleles alphaTmA63V and cTnI R193H, which approached a functional threshold. Interestingly, a combination of a CM myofilament deactivating mutant, troponin C G159D, together with an activating mutant, cTnIR193H, produced a hybrid phenotype that blunted the strong activating phenotype of cTnIR193H alone. This is evidence of neutralizing effects of activating/deactivating mutant alleles in combination. Taken together, this combinatorial mutant allele functional analysis lends molecular insight into disease severity and forms the foundation for a predictive model to deconstruct the myriad of possible CM double mutations in presenting patients.
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Affiliation(s)
- Jennifer Davis
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota, United States of America
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67
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Christiaans I, van Engelen K, van Langen IM, Birnie E, Bonsel GJ, Elliott PM, Wilde AAM. Risk stratification for sudden cardiac death in hypertrophic cardiomyopathy: systematic review of clinical risk markers. Europace 2010; 12:313-21. [PMID: 20118111 DOI: 10.1093/europace/eup431] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
We performed a systematic literature review of recommended 'major' and 'possible' clinical risk markers for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). We searched the Medline, Embase and Cochrane databases for articles published between 1971 and 2007. We included English language reports on HCM patients containing follow-up data on the endpoint (sudden) cardiac death using survival analysis. Analysis was undertaken using the quality of reporting of meta-analyses (QUORUM) statement checklist. The quality was checked using a quality assessment form from the Cochrane Collaboration. Thirty studies met inclusion criteria and passed quality assessment. The use of the six major risk factors (previous cardiac arrest or sustained ventricular tachycardia, non-sustained ventricular tachycardia, extreme left ventricular hypertrophy, unexplained syncope, abnormal blood pressure response, and family history of sudden death) in risk stratification for SCD as recommended by international guidelines was supported by the literature. In addition, left ventricular outflow tract obstruction seems associated with a higher risk of SCD. Our systematic review provides sound evidence for the use of the six major risk factors for SCD in the risk stratification of HCM patients. Left ventricular outflow tract obstruction could be included in the overall risk profile of patients with a marked left ventricular outflow gradient under basal conditions.
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Affiliation(s)
- Imke Christiaans
- Department of Clinical Genetics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
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68
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Abstract
Hypertrophic cardiomyopathy (HCM) is regarded as the most common cause of sudden cardiac death in young people (including trained athletes). However, assessing sudden death (SD) risk and identifying the most appropriate candidates for prophylactic device therapy is a complex process compounded by the unpredictability of the underlying arrhythmogenic substrate, absence of a single dominant and quantitative risk maker for this heterogeneous disease, and also the difficulty encountered in assembling sufficiently powered prospective and randomized trials in large patient populations. Patients with multiple risk factors and most young patients with one strong and unequivocal risk marker can be considered candidates for primary prevention defibrillators. Despite certain limitations, the current risk factor algorithm (when combined with a measure of individual physician judgment) has proved to be an effective strategy for targeting high-risk status. This approach has served the HCM patient population well, as evidenced by the significant appropriate defibrillator intervention rates, although a very small proportion of patients without conventional risk factors may also be at risk for SD. Indeed, the introduction of implantable defibrillators to the HCM patient population represents a new paradigm for clinical practice, offering the only proven protection against SD by virtue of effectively terminating ventricular tachycardia/fibrillation. In the process, implantable defibrillators have altered the natural history of HCM, potentially providing the opportunity of normal or near-normal longevity for many patients. Prevention of SD is now an integral, albeit challenging, component of HCM management.
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69
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McLeod CJ, Bos JM, Theis JL, Edwards WD, Gersh BJ, Ommen SR, Ackerman MJ. Histologic characterization of hypertrophic cardiomyopathy with and without myofilament mutations. Am Heart J 2009; 158:799-805. [PMID: 19853701 DOI: 10.1016/j.ahj.2009.09.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 09/03/2009] [Indexed: 01/19/2023]
Abstract
BACKGROUND Between 30% and 60% of clinical cases of hypertrophic cardiomyopathy (HC) can be attributed to mutations in the genes encoding cardiac myofilament proteins. Interestingly, it appears that the likelihood of an underlying myofilament mutation can be predicted by echocardiographic assessment of left ventricular morphology. However, it is not known whether genotypically characterized HC exists as a separate entity with discrete phenotypic morphology and histology or to what extent recognized polymorphisms of the renin-angiotensin-aldosterone system (RAAS) influence this relationship. The presence of cardiac myofilament and mutations and RAAS polymorphisms will have a strong association with the severity of histologic features of HC and characteristic septal shape. METHODS We conducted a retrospective review of histology specimens, obtained at septal myectomy among 181 patients with medically refractory symptomatic HC. All patients underwent comprehensive genetic analysis for mutations in 8 myofilament-encoding genes; a subset was genotyped for 6 known RAAS-polymorphisms. Patients underwent comprehensive echocardiography by an expert blinded to genotype and microscopic status. RESULTS Microscopically, severity of myocyte hypertrophy appears to be associated with the presence of recognized HC cardiac myofilament mutations (P = .03). Other histologic features characteristic of HC were not consistently associated with myofilament mutation status. A higher burden of pro-LVH RAAS polymorphisms also appeared to predict only myocyte hypertrophy (P = .01). The presence of RAAS polymorphisms was not associated with the development of a specific septal morphology (P = .6). CONCLUSION Myofilament-positive HC does not appear to represent a distinct clinical phenotypic entity as evidenced by specific histologic characteristics and septal shape.
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70
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Bos JM, Towbin JA, Ackerman MJ. Diagnostic, prognostic, and therapeutic implications of genetic testing for hypertrophic cardiomyopathy. J Am Coll Cardiol 2009; 54:201-11. [PMID: 19589432 DOI: 10.1016/j.jacc.2009.02.075] [Citation(s) in RCA: 239] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Revised: 02/20/2009] [Accepted: 02/24/2009] [Indexed: 02/05/2023]
Abstract
Over the last 2 decades, the pathogenic basis for the most common heritable cardiovascular disease, hypertrophic cardiomyopathy (HCM), has been investigated extensively. Affecting approximately 1 in 500 individuals, HCM is the most common cause of sudden death in young athletes. In recent years, genomic medicine has been moving from the bench to the bedside throughout all medical disciplines including cardiology. Now, genomic medicine has entered clinical practice as it pertains to the evaluation and management of patients with HCM. The continuous research and discoveries of new HCM susceptibility genes, the growing amount of data from genotype-phenotype correlation studies, and the introduction of commercially available genetic tests for HCM make it essential that the modern-day cardiologist understand the diagnostic, prognostic, and therapeutic implications of HCM genetic testing.
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Affiliation(s)
- J Martijn Bos
- Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
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TOWBIN JEFFREYA. Hypertrophic Cardiomyopathy. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2009; 32 Suppl 2:S23-31. [DOI: 10.1111/j.1540-8159.2009.02381.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Mitochondrial DNA analysis by multiplex denaturing high-performance liquid chromatography and selective sequencing in pediatric patients with cardiomyopathy. Genet Med 2009; 11:118-26. [PMID: 19265752 DOI: 10.1097/gim.0b013e318190356b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE Mitochondrial DNA testing is typically performed by targeted mutation analysis only. We applied a more comprehensive approach to study the mitochondrial genome in 24 pediatric patients with idiopathic cardiomyopathy. METHODS Patients in the cohort did not show overt multisystemic disease and were previously tested for mutations in a subset of structural genes associated with cardiomyopathy. Mutation screening of the mitochondrial DNA by multiplex denaturing high-performance liquid chromatography was complemented by sequence analysis. RESULTS We identified 130 individual (unique) sequence changes. Among several potentially pathogenic changes, a novel heteroplasmic mutation in nicotinamide adenine dinucleotide dehydrogenase subunit 4 (10677G>A) was identified in one fraternal twin with worse clinical symptoms than his sibling. Another proband carried homoplasmic mutation 13708G>A (in nicotinamide adenine dinucleotide dehydrogenase subunit 5) that has been associated with Leber's hereditary optic neuropathy. CONCLUSIONS Changes in mitochondrial DNA may represent a relatively rare cause of idiopathic pediatric cardiomyopathies and/or influence their phenotypic expression. Interpretation of variants with uncertain pathogenicity, however, currently impedes clinical diagnostic use of comprehensive mitochondrial DNA testing. Whereas combined use of multiplex denaturing high-performance liquid chromatography and sequencing is more comprehensive than targeted mutation analysis, measurement of additional functional parameters, such as tissue respiratory chain activity, remains important to establishing a definitive diagnosis.
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Maron BJ, Roberts WC, Arad M, Haas TS, Spirito P, Wright GB, Almquist AK, Baffa JM, Saul JP, Ho CY, Seidman J, Seidman CE. Clinical outcome and phenotypic expression in LAMP2 cardiomyopathy. JAMA 2009; 301:1253-9. [PMID: 19318653 PMCID: PMC4106257 DOI: 10.1001/jama.2009.371] [Citation(s) in RCA: 254] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Mutations in X-linked lysosome-associated membrane protein gene (LAMP2; Danon disease) produce a cardiomyopathy in young patients that clinically mimics severe hypertrophic cardiomyopathy (HCM) due to sarcomere protein mutations. However, the natural history and phenotypic expression of this newly recognized disease is incompletely resolved and its identification may have important clinical implications. OBJECTIVES To determine the clinical consequences, outcome, and phenotypic expression of LAMP2 cardiomyopathy associated with diagnostic and management strategies. DESIGN, SETTING, AND PATIENTS Clinical course and outcome were assessed prospectively in 7 young patients (6 boys) with defined LAMP2 mutations from the time of diagnosis (age 7-17 years; median, 14 years) to October 2008. Phenotypic expression of this disease was assessed both clinically and at autopsy. MAIN OUTCOME MEASURES Progressive heart failure, cardiac death, and transplant. RESULTS Over a mean (SD) follow-up of 8.6 (2.6) years, and by age 14 to 24 years, the study patients developed left ventricular systolic dysfunction (mean [SD] ejection fraction, 25% [7%]) and cavity enlargement, as well as particularly adverse clinical consequences, including progressive refractory heart failure and death (n = 4), sudden death (n = 1), aborted cardiac arrest (n = 1), or heart transplantation (n = 1). Left ventricular hypertrophy was particularly marked (maximum thickness, 29-65 mm; mean [SD], 44 [15] mm), including 2 patients with massive ventricular septal thickness of 60 mm and 65 mm at ages 23 and 14 years, respectively. In 6 patients, a ventricular pre-excitation pattern at study entry was associated with markedly increased voltages of R-wave or S-wave (15-145 mm; mean [SD], 69 [39] mm), and deeply inverted T-waves. Autopsy findings included a combination of histopathologic features that were consistent with a lysosomal storage disease (ie, clusters of vacuolated myocytes) but also typical of HCM due to sarcomere protein mutations (ie, myocyte disarray, small vessel disease, myocardial scarring). CONCLUSIONS LAMP2 cardiomyopathy is a profound disease process characterized by progressive clinical deterioration leading rapidly to cardiac death in young patients (<25 years). These observations underscore the importance of timely molecular diagnosis for predicting prognosis and early consideration of heart transplantation.
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Affiliation(s)
- Barry J Maron
- Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation, 920 E 28th St, Ste 620, Minneapolis, MN 55407, USA.
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Andersen PS, Havndrup O, Hougs L, Sørensen KM, Jensen M, Larsen LA, Hedley P, Thomsen ARB, Moolman-Smook J, Christiansen M, Bundgaard H. Diagnostic yield, interpretation, and clinical utility of mutation screening of sarcomere encoding genes in Danish hypertrophic cardiomyopathy patients and relatives. Hum Mutat 2009; 30:363-70. [PMID: 19035361 DOI: 10.1002/humu.20862] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The American Heart Association (AHA) recommends family screening for hypertrophic cardiomyopathy (HCM). We assessed the outcome of family screening combining clinical evaluation and screening for sarcomere gene mutations in a cohort of 90 Danish HCM patients and their close relatives, in all 451 persons. Index patients were screened for mutations in all coding regions of 10 sarcomere genes (MYH7, MYL3, MYBPC3, TNNI3, TNNT2, TPM1, ACTC, CSRP3, TCAP, and TNNC1) and five exons of TTN. Relatives were screened for presence of minor or major diagnostic criteria for HCM and tracking of DNA variants was performed. In total, 297 adult relatives (>18 years) (51.2%) fulfilled one or more criteria for HCM. A total of 38 HCM-causing mutations were detected in 32 index patients. Six patients carried two disease-associated mutations. Twenty-two mutations have only been identified in the present cohort. The genetic diagnostic yield was almost twice as high in familial HCM (53%) vs. HCM of sporadic or unclear inheritance (19%). The yield was highest in families with an additional history of HCM-related clinical events. In relatives, 29.9% of mutation carriers did not fulfil any clinical diagnostic criterion, and in 37.5% of relatives without a mutation, one or more criteria was fulfilled. A total of 60% of family members had no mutation and could be reassured and further follow-up ceased. Genetic diagnosis may be established in approximately 40% of families with the highest yield in familial HCM with clinical events. Mutation-screening was superior to clinical investigation in identification of individuals not at increased risk, where follow-up is redundant, but should be offered in all families with relatives at risk for developing HCM.
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Affiliation(s)
- Paal Skytt Andersen
- Department of Clinical Biochemistry, Statens Serum Institute, Copenhagen, Denmark.
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75
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Rodríguez JE, McCudden CR, Willis MS. Familial hypertrophic cardiomyopathy: basic concepts and future molecular diagnostics. Clin Biochem 2009; 42:755-65. [PMID: 19318019 DOI: 10.1016/j.clinbiochem.2009.01.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 01/24/2009] [Accepted: 01/28/2009] [Indexed: 11/26/2022]
Abstract
Familial hypertrophic cardiomyopathies (FHC) are the most common genetic heart diseases in the United States, affecting nearly 1 in 500 people. Manifesting as increased cardiac wall thickness, this autosomal dominant disease goes mainly unnoticed as most affected individuals are asymptomatic. Up to 1-2% of children and adolescents and 0.5-1% adults with FHC die of sudden cardiac death, making it critical to quickly and accurately diagnose FHC to institute therapy and potentially reduce mortality. However, due to the heterogeneity of the genetic defects in mainly sarcomere proteins, this is a daunting task even with current diagnostic methods. Exciting new methods utilizing high-throughput microarray technology to identify FHC mutations by a method known as array-based resequencing has recently been described. Additionally, next generation sequencing methodologies may aid in improving FHC diagnosis. In this review, we discuss FHC pathophysiology, the rationale for testing, and discuss the limitations and advantages of current and future diagnostics.
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Affiliation(s)
- Jessica E Rodríguez
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599-7525, USA
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Maron BJ, Seidman CE, Ackerman MJ, Towbin JA, Maron MS, Ommen SR, Nishimura RA, Gersh BJ. How should hypertrophic cardiomyopathy be classified? ACTA ACUST UNITED AC 2009; 2:81-5; discussion 86. [DOI: 10.1161/circgenetics.108.788703] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Barry J. Maron
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Christine E. Seidman
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Michael J. Ackerman
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Jeffrey A. Towbin
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Martin S. Maron
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Steve R. Ommen
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Rick A. Nishimura
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
| | - Bernard J. Gersh
- From the Hypertrophic Cardiomyopathy Center (B.J.M.), Minneapolis Heart Institute Foundation, Minneapolis, Minn; Department of Genetics (C.E.S.), Harvard Medical School, Boston, Mass; Departments of Medicine and Pediatrics/Divisions of Cardiovascular Diseases and Pediatric Cardiology (M.J.A., S.R.O., R.A.N., B.J.G.), Mayo Clinic, Rochester, Minn; Department of Pediatrics and Cardiology (J.A.T.), Baylor College of Medicine, Houston, Tex; and Hypertrophic Cardiomyopathy Center (M.S.M.), Tufts Medical
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Tester DJ, Ackerman MJ. Cardiomyopathic and Channelopathic Causes of Sudden Unexplained Death in Infants and Children. Annu Rev Med 2009; 60:69-84. [PMID: 18928334 DOI: 10.1146/annurev.med.60.052907.103838] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- David J. Tester
- Departments of Medicine, Pediatrics, and Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota 55905;
| | - Michael J. Ackerman
- Departments of Medicine, Pediatrics, and Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota 55905;
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Abstract
Sudden cardiac death (SCD) is one of the most common causes of death. An important number of sudden deaths, especially in the young, are due to genetic heart disorders, both with structural and arrhythmogenic abnormalities. In recent years, significant advances have been made in understanding the genetic basis of SCD. Identification of the genetic causes of sudden death is important because close relatives are also at potential risk of having a fatal cardiac condition. A comprehensive post-mortem investigation is vital to determine the cause and manner of death and provides the opportunity to assess the potential risk to the family after appropriate genetic counselling. In this paper, we present an update of the different genetic causes of sudden death, emphasizing their importance for the forensic pathologist due to his relevant role in the diagnosis and prevention of SCD.
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Genotype phenotype correlations of cardiac beta-myosin heavy chain mutations in Indian patients with hypertrophic and dilated cardiomyopathy. Mol Cell Biochem 2008; 321:189-96. [PMID: 18953637 DOI: 10.1007/s11010-008-9932-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 10/13/2008] [Indexed: 10/21/2022]
Abstract
The aim of the current study was to determine the frequency of mutations in the beta-myosin heavy chain gene (MYH7) in a cohort of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) and their families, and to investigate correlations between genotype and phenotype. About 130 consecutive patients diagnosed with HCM or DCM (69 with HCM and 61 with DCM) attending the cardiology clinic of Post Graduate Institute of Medical Education and Research were screened for mutations in the MYH7 gene. The control group for genetic studies consisted of 100 healthy subjects. We report 14 mutations in 6 probands (5 probands in HCM and 1 proband in DCM) and their family members. Out of these 6 mutations, 3 are new and are being reported for the first time. One known mutation (p.Gly716Arg) was found to be "de novo" which resulted in severe asymmetric septal hypertrophy (31 mm) and resulted in the sudden cardiac death (SCD) of the proband at the age of 21 years. Further, a DCM causing novel mutation p.Gly377Ser was identified which resulted in the milder phenotype. The present study shows that there is genetic and phenotypic heterogeneity of cardiomyopathies in Indian population. Further, the location and type of mutation in a given sarcomeric gene determines the severity and phenotypic plasticity in cardiomyopathies.
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80
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Stravopodis DJ, Zapheiropoulos AZ, Voutsinas G, Margaritis LH, Papassideri IS. A PCR-based integrated protocol for the structural analysis of the 13th exon of the human beta-myosin heavy chain gene (MYH7): development of a diagnostic tool for HCM disease. Exp Mol Pathol 2008; 84:245-50. [PMID: 18499102 DOI: 10.1016/j.yexmp.2008.03.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Accepted: 03/26/2008] [Indexed: 10/22/2022]
Abstract
Familial Hypertrophic Cardiomyopathy (FHC) constitutes a genetic disease of the sarcomere characterized by a Mendelian pattern of inheritance. A variety of different mutations affecting the at least eight sarcomeric gene products has been identified and the majority of them appear to function through a dominant negative mechanism. Family history analysis and genetic counseling have been widely adopted as integral tools for the evaluation and management of individuals with Hypertrophic Cardiomyopathy (HCM). Genetic testing of the disease has been progressively released into the clinical mainstream, thus rendering the development of novel and potent molecular diagnostic protocols an inevitable task. To this direction, we have evolved an integrated PCR-based molecular protocol, which through the utilization of novel "exonic" primers allows, among others, the structural analysis of the 13th exon of the human beta-myosin heavy chain gene locus (MYH7) mainly characterized by the critical for HCM Arginine residue 403 (R(403)). Interestingly, through a DNA sequencing approach, a single nucleotide substitution from "G" to "T" was detected in the adjacent 13th intron, thus divulging the versatile potential of the present molecular protocol to clinical practice.
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Affiliation(s)
- Dimitrios J Stravopodis
- Faculty of Biology, Department of Cell Biology and Biophysics, University of Athens, Panepistimiopolis 15784, Zografou, Athens, Greece
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81
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Morita H, Rehm HL, Menesses A, McDonough B, Roberts AE, Kucherlapati R, Towbin JA, Seidman JG, Seidman CE. Shared genetic causes of cardiac hypertrophy in children and adults. N Engl J Med 2008; 358:1899-908. [PMID: 18403758 PMCID: PMC2752150 DOI: 10.1056/nejmoa075463] [Citation(s) in RCA: 289] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND The childhood onset of idiopathic cardiac hypertrophy that occurs without a family history of cardiomyopathy can portend a poor prognosis. Despite morphologic similarities to genetic cardiomyopathies of adulthood, the contribution of genetics to childhood-onset hypertrophy is unknown. METHODS We assessed the family and medical histories of 84 children (63 boys and 21 girls) with idiopathic cardiac hypertrophy diagnosed before 15 years of age (mean [+/-SD] age, 6.99+/-6.12 years). We sequenced eight genes: MYH7, MYBPC3, TNNT2, TNNI3, TPM1, MYL3, MYL2, and ACTC. These genes encode sarcomere proteins that, when mutated, cause adult-onset cardiomyopathies. We also sequenced PRKAG2 and LAMP2, which encode metabolic proteins; mutations in these genes can cause early-onset ventricular hypertrophy. RESULTS We identified mutations in 25 of 51 affected children without family histories of cardiomyopathy and in 21 of 33 affected children with familial cardiomyopathy. Among 11 of the 25 children with presumed sporadic disease, 4 carried new mutations and 7 inherited the mutations. Mutations occurred predominantly (in >75% of the children) in MYH7 and MYBPC3; significantly more MYBPC3 missense mutations were detected than occur in adult-onset cardiomyopathy (P<0.005). Neither hypertrophic severity nor contractile function correlated with familial or genetic status. Cardiac transplantation and sudden death were more prevalent among mutation-positive than among mutation-negative children; implantable cardioverter-defibrillators were more frequent (P=0.007) in children with family histories that were positive for the mutation. CONCLUSIONS Genetic causes account for about half of presumed sporadic cases and nearly two thirds of familial cases of childhood-onset hypertrophy. Childhood-onset hypertrophy should prompt genetic analyses and family evaluations.
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Affiliation(s)
- Hiroyuki Morita
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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VAN SPAENDONCK-ZWARTS KARINY, VAN DEN BERG MAARTENP, VAN TINTELEN JPETER. DNA Analysis in Inherited Cardiomyopathies: Current Status and Clinical Relevance. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2008; 31 Suppl 1:S46-9. [DOI: 10.1111/j.1540-8159.2008.00956.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Miller MA, Anthony Gomes J, Fuster V. Risk stratification of sudden cardiac death in hypertrophic cardiomyopathy. ACTA ACUST UNITED AC 2007; 4:667-76. [DOI: 10.1038/ncpcardio1057] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Accepted: 09/11/2007] [Indexed: 01/13/2023]
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Abstract
PURPOSE OF REVIEW Hypertrophic cardiomyopathy is the most common identifiable cause of sudden death in the young. This review details the history of hypertrophic cardiomyopathy, recent discoveries in its genetic underpinnings and important genotype-phenotype relationships described in recent studies. RECENT FINDINGS Since the discovery of the genetic underpinnings of hypertrophic cardiomyopathy in 1989 hundreds of mutations scattered among at least 10 sarcomeric genes confer the pathogenetic substrate for this 'disease of the sarcomere/myofilament'. More recently, the genetic spectrum of hypertrophic cardiomyopathy has expanded to encompass mutations in Z-disc-associated genes (Z-disc hypertrophic cardiomyopathy) and glycogen storage diseases mimicking hypertrophic cardiomyopathy (metabolic hypertrophic cardiomyopathy). Recent genotype-phenotype studies have discovered an important relationship between the morphology of the left ventricle, its underlying genetic substrate and the long-term outcome of this disease. SUMMARY Genomic medicine has entered clinical practice and the diagnostic utility of genetic testing for hypertrophic cardiomyopathy is clearly evident, but with the growing number of hypertrophic cardiomyopathy-associated genes strategic choices have to be made. With recent discoveries in genotype-phenotype relationships, especially pertaining to the echocardiographic septal shape and the underlying pathogenetic mutation, time has come to subdivide the one disease we call hypertrophic cardiomyopathy.
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Affiliation(s)
- J Martijn Bos
- Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic College of Medicine, Rochester, MN, USA
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87
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García-Castro M, Reguero JR, Morís C, Alonso-Montes C, Berrazueta JR, Sainz R, Alvarez V, Coto E. Prevalence and spectrum of mutations in the sarcomeric troponin T and I genes in a cohort of Spanish cardiac hypertrophy patients. Int J Cardiol 2007; 121:115-6. [PMID: 17101185 DOI: 10.1016/j.ijcard.2006.08.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 08/04/2006] [Indexed: 11/15/2022]
Abstract
We sequenced the coding exons of the cardiac troponins T (TNNT2) and I (TNNI3) genes in 115 Spanish HCM-patients (32% with a family history of the disease). Only two (2%) had mutations in the TNNT2 (Arg278>Cys and Arg92>Lys). These mutations were associated with variable clinical outcomes. No patient had TNNI3-mutation. We also genotyped these patients and 320 healthy controls for a 5 bp insertion/deletion (I/D) polymorphism in intron 3 of TNNT2. DD-homozygotes for the 5 bp I/D polymorphism were significantly more frequent among the patients (OR=1.83, 95% CI=2.10-5.16).
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Tan BH, Iturralde-Torres P, Medeiros-Domingo A, Nava S, Tester DJ, Valdivia CR, Tusié-Luna T, Ackerman MJ, Makielski JC. A novel C-terminal truncation SCN5A mutation from a patient with sick sinus syndrome, conduction disorder and ventricular tachycardia. Cardiovasc Res 2007; 76:409-17. [PMID: 17897635 PMCID: PMC2100438 DOI: 10.1016/j.cardiores.2007.08.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 07/24/2007] [Accepted: 08/15/2007] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES Individual mutations in the SCN5A-encoding cardiac sodium channel alpha-subunit cause single cardiac arrhythmia disorders, but a few cause multiple distinct disorders. Here we report a family harboring an SCN5A mutation (L1821fs/10) causing a truncation of the C-terminus with a marked and complex biophysical phenotype and a corresponding variable and complex clinical phenotype with variable penetrance. METHODS AND RESULTS A 12-year-old male with congenital sick sinus syndrome (SSS), cardiac conduction disorder (CCD), and recurrent monomorphic ventricular tachycardia (VT) had mutational analysis that identified a 4 base pair deletion (TCTG) at position 5464-5467 in exon 28 of SCN5A. The mutation was also present in six asymptomatic family members only two of which showed mild ECG phenotypes. The deletion caused a frame-shift mutation (L1821fs/10) with truncation of the C-terminus after 10 missense amino acid substitutions. When expressed in HEK-293 cells for patch-clamp study, the current density of L1821fs/10 was reduced by 90% compared with WT. In addition, gating kinetic analysis showed a 5-mV positive shift in activation, a 12-mV negative shift of inactivation and enhanced intermediate inactivation, all of which would tend to reduce peak and early sodium current. Late sodium current, however, was increased in the mutated channels. CONCLUSIONS The L1821fs/10 mutation causes the most severe disruption of SCN5A structure for a naturally occurring mutation that still produces current. It has a marked loss-of-function and unique phenotype of SSS, CCD and VT with incomplete penetrance.
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Affiliation(s)
- Bi-Hua Tan
- Department of Medicine, Cardiovascular Section, University of Wisconsin-Madison, WI
| | | | - Argelia Medeiros-Domingo
- Instituto de Investigaciones Biomédicas, UNAM, Instituto Nacional de Ciencias Médicas y Nutrición, SZ, México
- The Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN
| | - Santiago Nava
- Instituto Nacional de Cardiología “Ignacio Chávez”, México
| | - David J Tester
- The Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN
| | - Carmen R. Valdivia
- Department of Medicine, Cardiovascular Section, University of Wisconsin-Madison, WI
| | - Teresa Tusié-Luna
- Instituto de Investigaciones Biomédicas, UNAM, Instituto Nacional de Ciencias Médicas y Nutrición, SZ, México
| | - Michael J. Ackerman
- The Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN
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Melacini P, Corbetti F, Calore C, Pescatore V, Smaniotto G, Pavei A, Bobbo F, Cacciavillani L, Iliceto S. Cardiovascular magnetic resonance signs of ischemia in hypertrophic cardiomyopathy. Int J Cardiol 2007; 128:364-73. [PMID: 17643520 DOI: 10.1016/j.ijcard.2007.06.023] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 06/12/2007] [Accepted: 06/30/2007] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recurrent myocardial ischemia has been recognized as playing an important role in the pathophysiology of hypertrophic cardiomyopathy (HCM) and cardiovascular magnetic resonance (CMR), with or without gadolinium, is a promising method of evaluating fibrosis, edema and hypoperfusion. The aim of this study is to evaluate the interrelationship between late enhancement (LE) and other signs of ischemia, such as edema and perfusion defects, and to relate them to clinical data in order to describe the stage of the disease. METHODS Forty-four patients were evaluated by CMR cine images, T2-weighted sequences for edema and LE sequences. First-pass perfusion study was obtained in 37 patients. Acute-subacute ischemic events were clinically defined as the presence of chest pain or new onset of ST-segment depression, end-stage phase by left ventricular ejection fraction <50% and maximal left ventricular wall thickness <25 mm. RESULTS Intramural patchy LE was found in 35/44 (80%) patients; extensive LE in 4/44 (9%). Edema was present in 24/44 (54%) patients and perfusion defects in 17/37 (46%). Simultaneous presence of patchy LE, edema and hypoperfusion in corresponding segments, was significantly associated to acute-subacute ischemic-phase parameters (p=0.02; RR 1.99, 95% C.I. 0.77-5.02). Extensive LE and perfusion defects in the absence of edema were significantly related to end-stage HCM (p<0.001; RR 13.7, 95% C.I. 1.83-102.05). CONCLUSIONS Using CMR in patients with HCM, we found focal tissue abnormalities consistent with regional ischemia at various stages. CMR provides important, clinically relevant information on the acuity, extent and functional relevance of ischemic injuries in HCM.
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Affiliation(s)
- Paola Melacini
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua Medical School, Padua, Italy.
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91
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Mogensen J. Troponin mutations in cardiomyopathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 592:201-26. [PMID: 17278367 DOI: 10.1007/978-4-431-38453-3_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Jens Mogensen
- Department of Cardiology, Skejby University Hospital Aarhus, Denmark
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92
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Michels M, Hoedemaekers Y, Kofflard M, Frohn-Mulder I, Dooijes D, Majoor-Krakauer D, Ten Cate F. Familial screening and genetic counselling in hypertrophic cardiomyopathy: the Rotterdam experience. Neth Heart J 2007; 15:184-90. [PMID: 17612681 PMCID: PMC1877969 DOI: 10.1007/bf03085978] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is a disease characterised by unexplained left ventricular hypertrophy (LVH) (i.e. LVH in the absence of another cardiac or systemic disease that could produce a similar degree of hypertrophy), electrical instability and sudden death (SD).Germline mutations in genes encoding for sarcomere proteins are found in more than half of the cases of unexplained LVH. The autosomal dominant inherited forms of HCM are characterised by incomplete penetrance and variability in clinical and echocardiographic features, prognosis and therapeutic modalities. The identification of the genetic defect in one of the HCM genes allows accurate presymptomatic detection of mutation carriers in a family. Cardiac evaluation of at-risk relatives enables early diagnosis and identification of those patients at high risk for SD, which can be the first manifestation of the disease in asymptomatic persons.In this article we present our experience with genetic testing and cardiac screening in our HCM population and give an overview of the current literature available on this subject. (Neth Heart J 2007;15:184-9.).
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Affiliation(s)
- M. Michels
- Department of Cardiology, Thoraxcentre, Erasmus Medical Centre, Rotterdam, the Netherlands
| | | | - M.J. Kofflard
- Albert Schweitzer Hospital, Dordrecht, the Netherlands
| | - I. Frohn-Mulder
- Department of Paediatric Cardiology, Thoraxcentre, Erasmus Medical Centre, Rotterdam, the Netherlands
| | - D. Dooijes
- Medical Centre, Rotterdam, the Netherlands
| | | | - F.J. Ten Cate
- Department of Cardiology, Thoraxcentre, Erasmus Medical Centre, Rotterdam, the Netherlands
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93
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Abstract
Hypertrophic cardiomyopathy (HCM) was the first cardiovascular disorder in which a genetic basis was identified. The disease is characterized by a marked thickening of the left ventricle and is the most common structural cause of sudden cardiac death in those aged under 35 years. HCM is primarily a disease of the sarcomere with over 250 mutations identified currently within 13 sarcomere-related genes. At present, genetic screening is available for the genes shown to cause HCM most frequently, with a mutation pick-up rate of up to 60%. Current research is focused on the identification of additional causative genes and elucidation into signaling mechanisms involved in HCM pathogenesis, as well as investigation of modifying factors that can alter the clinical phenotype in HCM. The unifying goal of these studies is to improve our understanding of disease pathogenesis in HCM, thereby facilitating the process of new diagnostic and therapeutic approaches in patients, ultimately leading to disease prevention and possible curative treatment.
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Affiliation(s)
- Joanne M Lind
- University of Sydney, Faculty of Medicine, Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Locked Bag No. 6, Newtown, NSW 2042, Australia.
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94
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Abstract
All patients with hypertrophic cardiomyopathy (HCM) should have five aspects of care addressed. An attempt should be made to detect the presence or absence of risk factors for sudden arrhythmic death. If the patient appears to be at high risk, discussion of the benefits and risks of ICD are indicated, and many such patients will be implanted. Symptoms are appraised and treated. Bacterial endocarditis prophylaxis is recommended. Patients are advised to avoid athletic competition and extremes of physical exertion. First degree family members should be screened with echocardiography and ECG.
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Affiliation(s)
- Mark V Sherrid
- Hypertrophic Cardiomyopathy Program and Echocardiography Laboratory, Department of Medicine, Division of Cardiology, St. Luke's-Roosevelt Hospital Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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95
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Mora R, Merino JL, Peinado R, Olias F, García-Guereta L, del Cerro MJ, Tarín MN, Molano J. Miocardiopatía hipertrófica: Baja frecuencia de mutaciones en el gen de la cadena pesada de la betamiosina cardiaca. Rev Esp Cardiol 2006. [DOI: 10.1157/13091891] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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96
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Cesario DA, Dec GW. Implantable Cardioverter- Defibrillator Therapy in Clinical Practice. J Am Coll Cardiol 2006; 47:1507-17. [PMID: 16630984 DOI: 10.1016/j.jacc.2005.09.077] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Accepted: 09/29/2005] [Indexed: 11/25/2022]
Abstract
Pharmacologic treatment of heart failure has led to dramatic improvements in survival and quality of life. Nonetheless, heart failure often progresses despite treatment with diuretics, angiotensin-converting enzyme inhibitors, beta-adrenergic blockers, aldosterone antagonists, and digoxin. Further, despite a steady decline in the risk of death from pump failure, many patients remain at high risk for sudden cardiac death. The annual incidence of sudden cardiac death in the U.S. alone has been estimated at 184,000 to over 400,000 cases. During the past decade, substantial advances have been made in the use of device-based therapy for this population. The role of the implantable cardioverter-defibrillator (ICD) continues to evolve in routine heart failure management. The current status of ICD therapy in the treatment of heart failure patients based on randomized clinical trial results and published practice guidelines is summarized in this review.
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97
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Binder J, Ommen SR, Gersh BJ, Van Driest SL, Tajik AJ, Nishimura RA, Ackerman MJ. Echocardiography-guided genetic testing in hypertrophic cardiomyopathy: septal morphological features predict the presence of myofilament mutations. Mayo Clin Proc 2006; 81:459-67. [PMID: 16610565 DOI: 10.4065/81.4.459] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To examine the relationship among age, septal morphological subtype, and presence of hypertrophic cardiomyopathy (HCM)-associated myofilament mutations. PATIENTS AND METHODS Comprehensive mutation analysis of the 8 HCM susceptibility genes that encode the myofilaments of the cardiac sarcomere was performed previously in 382 unrelated patients with HCM. Blinded to genotype status, we used echocardiography to characterize the left ventricular morphological features. Multivariate regression was used to assess the relationship among morphological subtypes, clinical data, and genetic variables. RESULTS The mean +/- SD age of the patients was 41.6+/-19.0 years, with 126 patients 50 years or older at initial diagnosis. The septal morphological subtype was sigmold in 181 (47%), reverse in 132 (35%), apical variant in 37 (10%), and neutral in 32 (8%). The HCM-associated myofilament mutations were Identified in 143 patients (37%). Multivariate analysis showed that the reverse curvature septal morphological subtype was a strong predictor of genotype-positive status (odds ratio, 21; P<.001). Overall, the yield of HCM genetic testing was 79% in the setting of reverse curvature HCM but only 8% in sigmold septal HCM. CONCLUSION In stark contrast to HCM in young patients, elderly patients with HCM display a predominantly sigmoid septal morphological subtype and uncommonly have perturbations of known HCM susceptibility genes. Independent of age, septal morphological subtype strongly predicts the presence or absence of HCM-associated myofilament mutations and may enable echocardiography-guided genetic testing for HCM.
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Affiliation(s)
- Josepha Binder
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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98
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Ackerman MJ, Van Driest SL, Bos M. Are longitudinal, natural history studies the next step in genotype-phenotype translational genomics in hypertrophic cardiomyopathy? J Am Coll Cardiol 2005; 46:1744-6. [PMID: 16256879 DOI: 10.1016/j.jacc.2005.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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99
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Chang AN, Harada K, Ackerman MJ, Potter JD. Functional Consequences of Hypertrophic and Dilated Cardiomyopathy-causing Mutations in α-Tropomyosin. J Biol Chem 2005; 280:34343-9. [PMID: 16043485 DOI: 10.1074/jbc.m505014200] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To study the functional consequences of various cardiomyopathic mutations in human cardiac alpha-tropomyosin (Tm), a method of depletion/reconstitution of native Tm and troponin (Tn) complex (Tm-Tn) in cardiac myofibril preparations has been developed. The endogenous Tm-Tn complex was selectively removed from myofibrils and replaced with recombinant wild-type or mutant proteins. Successful depletion and reconstitution steps were verified by SDS-gel electrophoresis and by the loss and regain of Ca2+-dependent regulation of ATPase activity. Five Tm mutations were chosen for this study: the hypertrophic cardiomyopathy (HCM) mutations E62Q, E180G, and L185R and the dilated cardiomyopathy (DCM) mutations E40K and E54K. Through the use of this new depletion/reconstitution method, the functional consequences of these mutations were determined utilizing myofibrillar ATPase measurements. The results of our studies showed that 1) depletion of >80% of Tm-Tn from myofibrils resulted in a complete loss of the Ca2+-regulated ATPase activity and a significant loss in the maximal ATPase activity, 2) reconstitution of exogenous wild-type Tm-Tn resulted in complete regain in the calcium regulation and in the maximal ATPase activity, and 3) all HCM-associated Tm mutations increased the Ca2+ sensitivity of ATPase activity and all had decreased abilities to inhibit ATPase activity. In contrast, the DCM-associated mutations both decreased the Ca2+ sensitivity of ATPase activity and had no effect on the inhibition of ATPase activity. These findings have demonstrated that the mutations which cause HCM and DCM disrupt discrete mechanisms, which may culminate in the distinct cardiomyopathic phenotypes.
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Affiliation(s)
- Audrey N Chang
- Department of Medicine, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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100
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Perkins MJ, Van Driest SL, Ellsworth EG, Will ML, Gersh BJ, Ommen SR, Ackerman MJ. Gene-specific modifying effects of pro-LVH polymorphisms involving the renin-angiotensin-aldosterone system among 389 unrelated patients with hypertrophic cardiomyopathy. Eur Heart J 2005; 26:2457-62. [PMID: 16087648 DOI: 10.1093/eurheartj/ehi438] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS The purpose of this study was to determine whether the deletion/insertion (D/I) polymorphism in the ACE-encoded angiotensin-converting enzyme or the pooled gene effect of five renin-angiotensin-aldosterone system (RAAS) polymorphisms were disease modifiers in a large cohort of unrelated patients with genotyped hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS Five different RAAS polymorphism genotypes were established by PCR amplification of the surrounding polymorphic regions of genomic DNA in a cohort of 389 unrelated patients comprehensively genotyped for HCM-causing mutations in eight sarcomeric/myofilament genes. Patient clinical data were archived in a database blinded both to the primary myofilament defect and the polymorphism genotype. Each patient was assessed with respect to ACE genotype as well as composite pro-left ventricular hypertrophy (LVH) RAAS polymorphism score (0-5). Overall, no clinical parameter correlated independently with ACE genotype. Subset analysis of the two most common genetic subtypes of HCM, MYBPC3 (myosin binding protein C) and MYH7 (beta myosin heavy chain), demonstrated a significant pro-LVH effect of DD-ACE only in patients with MYBPC3-HCM. In MYBPC3-HCM, left ventricular wall thickness was greater in patients with DD genotype (25.8+/-5 mm) compared with DI (21.8+/-4) or II genotype (20.8+/-5, P=0.01). Moreover, extreme hypertrophy (>30 mm) was only seen in MYBPC3-HCM patients who also hosted DD-ACE. An effect of RAAS pro-LVH score was evident only in the subgroup of patients with no previously identified myofilament mutation. CONCLUSION This study demonstrates that RAAS genotypes may modify the clinical phenotype of HCM in a disease gene-specific fashion rather than indiscriminately.
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Affiliation(s)
- Meghan J Perkins
- Mayo Medical School, Mayo Clinic College of Medicine, Rochester, MN, USA
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