1
|
Zhu M, Reyes KRL, Bilgili G, Siegel RJ, Lee Claggett B, Wong TC, Masri A, Naidu SS, Willeford A, Rader F. Medical Therapies to Improve Left Ventricular Outflow Obstruction and Diastolic Function in Hypertrophic Cardiomyopathy. JACC. ADVANCES 2023; 2:100622. [PMID: 38938334 PMCID: PMC11198509 DOI: 10.1016/j.jacadv.2023.100622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 08/10/2023] [Indexed: 06/29/2024]
Abstract
Hypertrophic cardiomyopathy-both obstructive hypertrophic cardiomyopathy (oHCM) and nonobstructive hypertrophic cardiomyopathy (nHCM) subtypes-is the most common monogenic cardiomyopathy. Its structural hallmarks are abnormal thickening of the myocardium and hyperdynamic contractility, while its hemodynamic consequences are left ventricular outflow tract or intracavitary obstruction (in oHCM) and diastolic dysfunction (in both oHCM and nHCM). Several medical therapies are routinely used to improve these abnormalities with the goal to decrease symptom burden in patients with HCM. Current guidelines recommend nonvasodilating beta blockers as first-line and nondihydropyridine calcium channel blockers followed by disopyramide as second- and third-line medical therapies for symptomatic oHCM and give weaker recommendations for beta blockers and calcium channel blockers in nHCM. These recommendations are based on small studies-mostly nonrandomized-and expert opinion. Our review will summarize the available data on the effectiveness of commonly prescribed medications used in oHCM and nHCM to uncover knowledge gaps, but also new data on cardiac myosin inhibitors.
Collapse
Affiliation(s)
- Mason Zhu
- Georgetown University School of Medicine, Washington, DC, USA
| | | | - Gizem Bilgili
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Robert J. Siegel
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Brian Lee Claggett
- Cardiovascular Division, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Timothy C. Wong
- Division of Cardiology, Department of Medicine, University of Pittsburgh Medical Center, Heart and Vascular Institute, Pittsburgh, Pennsylvania, USA
| | - Ahmad Masri
- Knight Cardiovascular Institute, Oregon Health Sciences University Medical Center, Portland, Oregon, USA
| | - Srihari S. Naidu
- Department of Cardiology, Westchester Medical Center, Valhalla, New York, USA
| | - Andrew Willeford
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California-San Diego Health, San Diego, California, USA
| | - Florian Rader
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| |
Collapse
|
2
|
Best LG, O’Leary M, O’Leary R, Lawrence W, Torgerson DG. Return of Participants' Incidental Genetic Research Findings: Experience from a Case-Control Study of Asthma in an American Indian Community. J Pers Med 2023; 13:1407. [PMID: 37763174 PMCID: PMC10532458 DOI: 10.3390/jpm13091407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 09/14/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
The proper communication of clinically actionable findings to participants of genetic research entails important ethical considerations, but has been challenging for a variety of reasons. We document an instance of the return of individual genetic results in the context of a very rural American Indian community, in hopes of providing insight to other investigators about potentially superior or inferior courses of action. This was a case/control study of asthma among 324 pediatric participants. Subsequently, microarray genotype data became available, providing over 2 million variants, incidentally including some conferring risk for conditions for which the American College of Medical Genetics recommends return of results. The study investigators engaged in extensive consultation with the IRB, the tribal government, and local clinicians to better inform our approach. We were able to notify the two participants heterozygous for the one clinically actionable variant identified. One participant welcomed this information and proceeded to obtain further clinical work-up; the other participant declined further follow-up. While demanding considerable time and effort, the return of clinically actionable genetic results is important from both an ethical perspective and to provide an improved trust relationship with the community of research participants.
Collapse
Affiliation(s)
- Lyle G. Best
- School of Medicine and Health Sciences, University of North Dakota, Grand Forks, ND 58202, USA
- Missouri Breaks Industries Research Inc., Eagle Butte, SD 57625, USA; (M.O.); (R.O.); (W.L.)
| | - Marcia O’Leary
- Missouri Breaks Industries Research Inc., Eagle Butte, SD 57625, USA; (M.O.); (R.O.); (W.L.)
| | - Rae O’Leary
- Missouri Breaks Industries Research Inc., Eagle Butte, SD 57625, USA; (M.O.); (R.O.); (W.L.)
| | - Wendy Lawrence
- Missouri Breaks Industries Research Inc., Eagle Butte, SD 57625, USA; (M.O.); (R.O.); (W.L.)
| | - Dara G. Torgerson
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA 94158, USA;
| |
Collapse
|
3
|
Kucher AN, Valiakhmetov NR, Salakhov RR, Golubenko MV, Pavlyukova EN, Nazarenko MS. Phenotype variation of hypertrophic cardiomyopathy in carriers of the p.Arg870His pathogenic variant in the MYH7 gene. BULLETIN OF SIBERIAN MEDICINE 2022. [DOI: 10.20538/1682-0363-2022-3-205-216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The review analyzes variability of clinical manifestations of p.Arg870His in the MYH7 gene, which is repeatedly registered in patients with hypertrophic cardiomyopathy (HCM). The analysis involves the data from scientific publications obtained as a search result in the PubMed, СlinVar, and eLibrary.ru databases, as well as authors’ own results. A wide range of phenotypic manifestations have been revealed in carriers of p.Arg870His, from the asymptomatic to severe course, rapid progression, and early death. The review considers possible factors that modify the effect of the pathogenic variant (i.e. dosage of the pathogenic variant, the presence of other unfavorable genetic variants, etc.). The importance of accumulating information on the clinical features of HCM in the carriers of specific gene variants is emphasized in order to clarify their pathogenicity and to identify factors modifying the clinical outcome, which is important for the choice of the treatment strategy for HCM.
Collapse
Affiliation(s)
- A. N. Kucher
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - N. R. Valiakhmetov
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - R. R. Salakhov
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences; Siberian State Medical University
| | - M. V. Golubenko
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - E. N. Pavlyukova
- Cardiology Research Institute, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences
| | - M. S. Nazarenko
- Research Institute of Medical Genetics, Tomsk National Research Medical Center (NRMC), Russian Academy of Sciences; Siberian State Medical University
| |
Collapse
|
4
|
Reyes KRL, Bilgili G, Rader F. Mavacamten: A First-in-class Oral Modulator of Cardiac Myosin for the Treatment of Symptomatic Hypertrophic Obstructive Cardiomyopathy. Heart Int 2022; 16:91-98. [PMID: 36741099 PMCID: PMC9872784 DOI: 10.17925/hi.2022.16.2.91] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 08/04/2022] [Indexed: 12/25/2022] Open
Abstract
Hypertrophic cardiomyopathy is the most common monogenic cardiovascular disease that is caused by sarcomeric protein gene mutations. A hallmark of the most common form of the disease is outflow obstruction secondary to systolic narrowing of the left ventricular outflow tract from septal hypertrophy, mitral valve abnormalities and, most importantly, hyperdynamic contractility. Recent mechanistic studies have identified excessive myosin adenosine triphosphatase activation and actin-myosin cross-bridging as major underlying causes. These studies have led to the development of mavacamten, a first-in-class myosin adenosine triphosphatase inhibitor and the first specific therapy for hypertrophic obstructive cardiomyopathy. Preclinical and subsequent pivotal clinical studies have demonstrated the efficacy and safety of mavacamten. A remarkable improvement among treated patients in peak oxygen consumption, functional capacity, symptom relief and post-exercise left ventricular outflow tract gradient, along with dramatic reductions in heart failure biomarkers, suggests that this new medication will be transformative for the symptom management of hypertrophic obstructive cardiomyopathy. There is also hope and early evidence that mavacamten may delay or obviate the need for invasive septal reduction therapies. In this article, we review the current evidence for the efficacy and safety of mavacamten and highlight important considerations for its clinical use.
Collapse
Affiliation(s)
| | - Gizem Bilgili
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Florian Rader
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| |
Collapse
|
5
|
Miyawaki N, Toyota T, Higasa K, Nakamura T, Furukawa Y. Successful pregnancy and delivery in a young-onset hypertrophic cardiomyopathy patient with a novel doublet-base substitution in the MYH7 gene. J Cardiol Cases 2022; 27:8-11. [PMID: 36618848 PMCID: PMC9808452 DOI: 10.1016/j.jccase.2022.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 08/31/2022] [Accepted: 09/11/2022] [Indexed: 11/05/2022] Open
Abstract
Herein, we report the case of a young-onset female hypertrophic cardiomyopathy (HCM) patient with severe left ventricular outflow tract obstruction who had a family history of premature sudden cardiac death. Despite the severe HCM phenotype, the patient was successfully managed by low-dose bisoprolol during two peripartum periods after a percutaneous transluminal septal myocardial ablation.We performed whole-genome sequencing analysis and found a novel doublet-base substitution (DBS) in the MYH7 gene (c.2608_2609delinsTT, p.R870F) in this patient. Her children were also genetically tested after careful genetic counselling to their parents, and one of her children at 1-year-old with left ventricular hypertrophy was found to have the same gene mutation. The location of the DBS in a functionally important domain and the inheritance of the same mutation in the offspring with the HCM phenotype suggested that this mutation in the MYH7 gene was responsible for the severe HCM phenotype. Proactive genetic testing would provide beneficial information for appropriate follow-up and initiation of therapy in children with possibly pathogenic gene mutations; however, revisions of genetic counselling may be considered according to their growth. Learning objective Hypertrophic cardiomyopathy (HCM) patients with severe left ventricular outflow tract obstruction are at a high risk of hemodynamic deterioration during pregnancy. Preceding myocardial ablation therapy and a careful medical management during peripartum period may enable safe pregnancy and delivery in severe obstructive HCM patients. A novel doublet-base substitution in the MYH7 gene (c.2608_2609delinsTT, p.R870F) was found as a likely pathogenic mutation of young-onset severe HCM.
Collapse
Affiliation(s)
- Norihisa Miyawaki
- Department of Cardiovascular Medicine, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Toshiaki Toyota
- Department of Cardiovascular Medicine, Kobe City Medical Center General Hospital, Kobe, Japan
| | - Koichiro Higasa
- Department of Genome Analysis, Institute of Biomedical Science, Kansai Medical University, Hirakata, Japan
| | - Tomoyuki Nakamura
- Department of Pharmacology, Kansai Medical University, Hirakata, Japan
| | - Yutaka Furukawa
- Department of Cardiovascular Medicine, Kobe City Medical Center General Hospital, Kobe, Japan,Corresponding author at: Department of Cardiovascular Medicine, Kobe City Medical Center General Hospital, 2-1-1 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan.
| |
Collapse
|
6
|
Variants in MHY7 Gene Cause Arrhythmogenic Cardiomyopathy. Genes (Basel) 2021; 12:genes12060793. [PMID: 34067482 PMCID: PMC8224781 DOI: 10.3390/genes12060793] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/14/2021] [Accepted: 05/20/2021] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Arrhythmogenic Cardiomyopathy (ACM) is a disease of the cardiac muscle, characterized by frequent ventricular arrhythmias and functional/ structural abnormalities, mainly of the right ventricle. To date, 20 different genes have been associated with ACM and the majority of them encode for desmosomal proteins. In this study, we describe the characterization of two novel variants in MHY7 gene, segregating in two ACM families. MYH7 encodes for myosin heavy chain β (MHC-β) isoform, involved in cardiac muscle contractility. METHOD AND RESULTS In family A, the autopsy revealed ACM with biventricular involvement in both the proband and his father. In family B, the proband had been diagnosed as affected by ACM and implanted with implantable cardioverter defibrillator (ICD), due to ECG evidence of monomorphic ventricular tachycardia after syncope. After clinical evaluation, a molecular diagnosis was performed using a NGS custom panel. The two novel variants identified predicted damaging, located in a highly conserved domain: c. 2630T>C is not described while c.2609G>A has a frequency of 0.00000398. In silico analyses evaluated the docking characteristics between proteins using the Haddock2.2 webserver. CONCLUSIONS Our results reveal two variants in sarcomeric genes to be the molecular cause of ACM, further increasing the genetic heterogeneity of the disease; in fact, sarcomeric variants are usually associated with HCM phenotype. Studies on the role of sarcomere genes in the pathogenesis of ACM are surely recommended in those ACM patients negative for desmosomal mutation screening.
Collapse
|
7
|
Kolokotronis K, Kühnisch J, Klopocki E, Dartsch J, Rost S, Huculak C, Mearini G, Störk S, Carrier L, Klaassen S, Gerull B. Biallelic mutation in MYH7 and MYBPC3 leads to severe cardiomyopathy with left ventricular noncompaction phenotype. Hum Mutat 2019; 40:1101-1114. [PMID: 30924982 DOI: 10.1002/humu.23757] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 03/21/2019] [Accepted: 03/26/2019] [Indexed: 01/11/2023]
Abstract
Dominant mutations in the MYH7 and MYBPC3 genes are common causes of inherited cardiomyopathies, which often demonstrate variable phenotypic expression and incomplete penetrance across family members. Biallelic inheritance is rare but allows gaining insights into the genetic mode of action of single variants. Here, we present three cases carrying a loss-of-function (LoF) variant in a compound heterozygous state with a missense variant in either MYH7 or MYBPC3 leading to severe cardiomyopathy with left ventricular noncompaction. Most likely, MYH7 haploinsufficiency due to one LoF allele results in a clinical phenotype only in compound heterozygous form with a missense variant. In contrast, haploinsufficiency in MYBPC3 results in a severe early-onset ventricular noncompaction phenotype requiring heart transplantation when combined with a de novo missense variant on the second allele. In addition, the missense variant may lead to an unstable protein, as overall only 20% of the MYBPC3 protein remain detectable in affected cardiac tissue compared to control tissue. In conclusion, in patients with early disease onset and atypical clinical course, biallelic inheritance or more complex variants including copy number variations and de novo mutations should be considered. In addition, the pathogenic consequence of variants may differ in heterozygous versus compound heterozygous state.
Collapse
Affiliation(s)
| | - Jirko Kühnisch
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Experimental and Clinical Research Center (ECRC), a Joint Cooperation between the Charité Medical Faculty and the Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Berlin, Germany
| | - Eva Klopocki
- Institute of Human Genetics, Biocenter, Julius-Maximilians-University, Würzburg, Germany
| | - Josephine Dartsch
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Experimental and Clinical Research Center (ECRC), a Joint Cooperation between the Charité Medical Faculty and the Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany
| | - Simone Rost
- Institute of Human Genetics, Biocenter, Julius-Maximilians-University, Würzburg, Germany
| | - Cathleen Huculak
- Department of Medical Genetics, Alberta Health Services, Calgary, Alberta, Canada
| | - Giulia Mearini
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Stefan Störk
- Comprehensive Heart Failure Center (CHFC) and Department of Medicine I, University and University Hospital Würzburg, Würzburg, Germany
| | - Lucie Carrier
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Sabine Klaassen
- Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Experimental and Clinical Research Center (ECRC), a Joint Cooperation between the Charité Medical Faculty and the Max-Delbrück-Center for Molecular Medicine (MDC), Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Berlin, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Department of Pediatric Cardiology, Charité - University Medicine Berlin, Berlin, Germany
| | - Brenda Gerull
- Comprehensive Heart Failure Center (CHFC) and Department of Medicine I, University and University Hospital Würzburg, Würzburg, Germany
| |
Collapse
|
8
|
Marsiglia JDC, Pereira AC. Hypertrophic cardiomyopathy: how do mutations lead to disease? Arq Bras Cardiol 2014; 102:295-304. [PMID: 24714796 PMCID: PMC3987320 DOI: 10.5935/abc.20140022] [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: 06/13/2013] [Accepted: 08/23/2013] [Indexed: 12/13/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common monogenic genetic cardiac
disease, with an estimated prevalence of 1:500 in the general population. Clinically,
HCM is characterized by hypertrophy of the left ventricle (LV) walls, especially the
septum, usually asymmetric, in the absence of any cardiac or systemic disease that
leads to a secondary hypertrophy. The clinical course of the disease has a large
inter- and intrafamilial heterogeneity, ranging from mild symptoms of heart failure
late in life to the onset of sudden cardiac death at a young age and is caused by a
mutation in one of the genes that encode a protein from the sarcomere, Z-disc or
intracellular calcium modulators. Although many genes and mutations are already known
to cause HCM, the molecular pathways that lead to the phenotype are still unclear.
This review focus on the molecular mechanisms of HCM, the pathways from mutation to
clinical phenotype and how the disease's genotype correlates with phenotype.
Collapse
Affiliation(s)
- Júlia Daher Carneiro Marsiglia
- Mailing Address: Júlia Daher Carneiro Marsiglia, Av. Dr. Enéas de
Carvalho Aguiar, 44, Cerqueira César. Postal Code 05403- 900, São Paulo, SP - Brazil.
E-mail: ;
| | | |
Collapse
|
9
|
Capek P, Vondrasek J, Skvor J, Brdicka R. Hypertrophic cardiomyopathy: from mutation to functional analysis of defective protein. Croat Med J 2012; 52:384-91. [PMID: 21674835 PMCID: PMC3118724 DOI: 10.3325/cmj.2011.52.384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Aim To analyze the genesis of hypertrophic cardiomyopathy on a large cohort of patients from molecular genetics point of view and perform the functional analysis of the 3D molecular model of defective myosin-7 protein in silico. Methods The study enrolled 153 patients with diagnosed hypertrophic cardiomyopathy from different parts of the Czech Republic. DNA samples were analyzed for mutations in exons 21 and 22 of the MYH7 gene, which have been associated with high mutation clustering. The 3D model of human myosin-7 was built using the x-ray structure of nucleotide-free scallop myosin S1 as the structural template. We performed de novo structure prediction of mutant and wild type peptides spanning the 769-788 amino acids region of the myosin-7 protein. Results The Arg870His and Asp778Val amino acid alterations were found in 2 unrelated patients with a severe form of hypertrophic cardiomyopathy. The Asp778Val variation was chosen for subsequent 3D molecular modeling in silico. The mutation of the Asp by Val not only changes the character of the interaction pattern with other amino acids or ions but Val, being a small hydrophobic amino acid, can also completely change the stability of the region. Conclusion Mutation location in the MYH7 gene and changes in amino acid composition may have a crucial negative impact on the outcome of the disease in patients with hypertrophic cardiomyopathy. In addition, a mutation that changes the charge of the amino acid is more likely to affect protein function than a conservative mutation.
Collapse
Affiliation(s)
- Pavel Capek
- Department of Anthropology and Human Genetics, Charles University, Prague, Czech Republic.
| | | | | | | |
Collapse
|
10
|
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.
Collapse
Affiliation(s)
- Reena Tanjore
- Department of Genetics, Osmania University, Jamai Osmania P.O., Hyderabad-500 007, India
| | | | | | | | | | | |
Collapse
|
11
|
Abstract
This review provides an historical and personal perspective on the discovery of genetic causes for hypertrophic cardiomyopathy (HCM). Extraordinary insights by physicians who initially detailed remarkable and varied manifestations of the disorder, collaboration among multidisciplinary teams with skills in clinical diagnostics and molecular genetics, and hard work by scores of trainees solved the etiologic riddle of HCM and unexpectedly demonstrated mutations in sarcomere protein genes as the cause of disease. In addition to celebrating 20 years of genetic research in HCM, this article serves as an introductory overview to a thematic review series that will present contemporary advances in the field of hypertrophic heart disease. Through the continued application of advances in genetic methodologies, combined with biochemical and biophysical analyses of the consequences of human mutations, fundamental knowledge about HCM and sarcomere biology has emerged. Expanding research to elucidate the mechanisms by which subtle genetic variation in contractile proteins remodel the human heart remains an exciting opportunity, one with considerable promise to provide new strategies to limit or even prevent HCM pathogenesis.
Collapse
Affiliation(s)
- Christine E Seidman
- Cardiovascular Division, Department of Genetics, Brigham & Women's Hospital, Boston, MA 02115, USA.
| | | |
Collapse
|
12
|
Kimura A. Molecular basis of hereditary cardiomyopathy: abnormalities in calcium sensitivity, stretch response, stress response and beyond. J Hum Genet 2010; 55:81-90. [PMID: 20075948 DOI: 10.1038/jhg.2009.138] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cardiomyopathy is caused by functional abnormality of cardiac muscle. The functional abnormality involved in its etiology includes both extrinsic and intrinsic factors, and cardiomyopathy caused by the intrinsic factors is called as idiopathic or primary cardiomyopathy. There are several clinical types of primary cardiomyopathy including hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Linkage studies and candidate gene approaches have explored the disease genes for hereditary primary cardiomyopathy. The most notable finding was that mutations in the same disease gene can be found in different clinical types of cardiomyopathy. Functional analyses of disease-related mutations have revealed that characteristic functional alterations are associated with the clinical types, such that increased and decreased Ca(2+) sensitivity due to sarcomere mutations are associated with HCM and DCM, respectively. In addition, our recent studies have suggested that mutations in the Z-disc components found in HCM and DCM may result in increased and decreased stiffness of sarcomere; that is, stiff sarcomere and loose sarcomere, respectively, and hence altered stretch response. More recently, mutations in the components of I region were found in hereditary cardiomyopathy and the functional analyses of the mutations suggested that the altered stress response was associated with cardiomyopathy, further complicating the etiology and pathogenesis. However, elucidation of genetic etiology and functional alterations caused by the mutations shed lights on the new therapeutic approaches to hereditary cardiomyopathy, such that treatment of DCM with a Ca(2+) sensitizer prevented the disease in a mouse model.
Collapse
Affiliation(s)
- Akinori Kimura
- Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, Japan.
| |
Collapse
|
13
|
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.
Collapse
|
14
|
Tsoutsman T, Bagnall RD, Semsarian C. Impact of multiple gene mutations in determining the severity of cardiomyopathy and heart failure. Clin Exp Pharmacol Physiol 2008; 35:1349-57. [PMID: 18761664 DOI: 10.1111/j.1440-1681.2008.05037.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. Familial hypertrophic cardiomyopathy (FHC) is a primary cardiac disorder characterized by myocardial hypertrophy that demonstrates substantial diversity in both genetic causes and clinical manifestations. 2. Clinical heterogeneity can be explained by the causative gene (at least 13 have been identified to date), the position of the amino acid residue affected by a mutation within the protein (over 450 mutations have been reported to date) and modifying genetic and environmental factors. 3. Multiple mutations are found in up to 5% of human FHC cases, who typically present with a more severe phenotype compared with single-mutation carriers (i.e. earlier onset of disease, greater left ventricular hypertrophy and a higher incidence of sudden cardiac death events). 4. Multiple mutations usually involve MYH7, MYBPC3 and, to a lesser extent, TNNI2, reflecting the higher contribution of mutations in these genes to FHC. 5. Multiple-mutation mouse models appear to mimic the human multiple-mutation phenotype and, thus, will help improve our understanding of disease pathogenesis. The models provide a tool for future studies of disease mechanisms and signalling pathways in FHC and its sequelae (i.e. heart failure and sudden death), thereby allowing identification of novel targets for potential therapies and disease prevention strategies.
Collapse
Affiliation(s)
- Tatiana Tsoutsman
- Agnes Ginges Centre for Molecular Cardiology, Centenary Institute, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | | | | |
Collapse
|
15
|
Bashyam MD, Savithri GR, Gopikrishna M, Narasimhan C. A p.R870H mutation in the beta-cardiac myosin heavy chain 7 gene causes familial hypertrophic cardiomyopathy in several members of an Indian family. Can J Cardiol 2007; 23:788-90. [PMID: 17703256 PMCID: PMC2651383 DOI: 10.1016/s0828-282x(07)70828-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Familial hypertrophic cardiomyopathy is an autosomal dominant genetic disorder characterized mainly by left ventricular hypertrophy and myocyte disarray; it is the most common cause of sudden death in otherwise healthy individuals. More than 270 mutations in genes encoding the cardiac sarcomere have been identified. Attempts to establish a genotype-phenotype correlation for each of the mutations have not been highly successful. It has been suggested that additional genetic loci, as well as nongenetic factors such as lifestyle, gender and age, may play a role in modulating the clinical presentation of the disease. The p.R870H mutation has been identified as the cause of familial hypertrophic cardiomyopathy in an Indian family. The results indicate that the disease phenotype varied among various affected members of the family, and the variation may be attributed to factors, such as gender and gene dosage.
Collapse
Affiliation(s)
- Murali D Bashyam
- Laboratory of Molecular Oncology, Centre for DNA Fingerprinting and Diagnostics (CDFD), Nacharam, India.
| | | | | | | |
Collapse
|
16
|
Konno T, Fujino N, Hayashi K, Uchiyama K, Masuta E, Katoh H, Sakamoto Y, Tsubokawa T, Ino H, Yamagishi M. Differences in the diagnostic value of various criteria of negative T waves for hypertrophic cardiomyopathy based on a molecular genetic diagnosis. Clin Sci (Lond) 2007; 112:577-82. [PMID: 17263690 DOI: 10.1042/cs20060293] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Differences in the diagnostic value of a variety of definitions of negative T waves for HCM (hypertrophic cardiomyopathy) have not yet been clarified, resulting in a number of definitions being applied in previous studies. The aim of the present study was to determine the most accurate diagnostic definition of negative T waves for HCM in genotyped populations. Electrocardiographic and echocardiographic findings were analysed in 161 genotyped subjects (97 carriers and 64 non-carriers). We applied three different criteria that have been used in previous studies: Criterion 1, negative T wave >10 mm in depth in any leads; Criterion 2, negative T wave >3 mm in depth in at least two leads; and Criterion 3, negative T wave >1 mm in depth in at least two leads. Of the three criteria, Criterion 3 had the highest sensitivity (43% compared with 5 and 26% in Criterion 1 and Criterion 2 respectively; P<0.0001) and retained a specificity of 95%, resulting in the highest accuracy. In comparison with abnormal Q waves, negative T waves for Criterion 3 had a lower sensitivity in detecting carriers without LVH (left ventricular hypertrophy) (12.9% for negative T waves compared with 22.6% for abnormal Q waves). On the other hand, in detecting carriers with LVH, the sensitivity of negative T waves increased in a stepwise direction with the increasing extent of LVH (P<0.001), whereas there was less association between the sensitivity of abnormal Q waves and the extent of LVH. In conclusion, Criterion 3 for negative T waves may be the most accurate definition of HCM based on genetic diagnoses. Negative T waves may show different diagnostic value according to the different criteria and phenotypes in genotyped populations with HCM.
Collapse
Affiliation(s)
- Tetsuo Konno
- Department of Internal Medicine, Division of Cardiovascular Medicine, Kanazawa University Graduate School of Medical Science, Takara-machi, Kanazawa, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Laredo R, Monserrat L, Hermida-Prieto M, Fernández X, Rodríguez I, Cazón L, Alvariño I, Dumont C, Piñón P, Peteiro J, Bouzas B, Castro-Beiras A. [Beta-myosin heavy-chain gene mutations in patients with hypertrophic cardiomyopathy]. Rev Esp Cardiol 2007; 59:1008-18. [PMID: 17125710 DOI: 10.1157/13093977] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION AND OBJECTIVES To determine the frequency of mutations in the beta-myosin heavy-chain gene (MYH7) in a cohort of patients with hypertrophic cardiomyopathy (HCM) and their families, and to investigate correlations between genotype and phenotype. METHODS Single-strand conformation polymorphism analysis and sequencing of fragments with abnormal MYH7 gene mobility were carried out in 128 consecutive index patients with HCM. The phenotypes of patients with and without mutations were compared and the phenotypes of identified families were recorded. RESULTS A total of 11 mutations were found in 13 families (10%); 7/11 had been previously described. The I736T mutation was found in three families and the A797T in two. One patient had two mutations (i.e., I736T and R787H). Mutations were more frequent in patients with a family history of sudden death (31%) and in those with severe hypertrophy (39% had a thickness > or = 30 mm). Mutations were found in 29 of 42 members of the 13 families, including six family members (20%) who were healthy carriers and aged < or = 36 years. Sudden death had occurred in eight members of four families: four in two families with the I736T mutation, one in a family with A797T, one in a family with R870H, and two in a family with A901P. CONCLUSIONS MYH7 mutations were present in 10% of our families. Mutations were more frequent in patients with a family history of sudden death and in those with severe hypertrophy. Most mutations had been described previously. Some appeared in several families. For some mutations, the correlation between genotype and phenotype was stable, while for others, there were marked differences between the phenotypes of the index patients and their relatives, suggesting the presence of additional genetic factors that have yet to be identified.
Collapse
Affiliation(s)
- Rafael Laredo
- Servicio de Cardiología, Complejo Hospitalario Universitario Juan Canalejo e Instituto Universitario de Ciencias de la Salud de la Universidad de A Coruña, A Coruña, Spain
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Tanjore RR, Sikindlapuram AD, Calambur N, Thakkar B, Kerkar PG, Nallari P. Genotype-phenotype correlation of R870H mutation in hypertrophic cardiomyopathy. Clin Genet 2006; 69:434-6. [PMID: 16650083 DOI: 10.1111/j.1399-0004.2006.00599.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
19
|
Konno T, Shimizu M, Ino H, Fujino N, Hayashi K, Uchiyama K, Kaneda T, Inoue M, Fujita T, Masuta E, Funada A, Mabuchi H. Differences in diagnostic value of four electrocardiographic voltage criteria for hypertrophic cardiomyopathy in a genotyped population. Am J Cardiol 2005; 96:1308-12. [PMID: 16253604 DOI: 10.1016/j.amjcard.2005.06.078] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 06/15/2005] [Accepted: 06/15/2005] [Indexed: 11/25/2022]
Abstract
The diagnostic value of various classic electrocardiographic (ECG) voltage criteria for hypertrophic cardiomyopathy (HC) has not been established in a genotyped population. This study aimed to determine the most accurate diagnostic definition of classic ECG voltage criteria for detecting carriers of HC. ECG and echocardiographic findings were analyzed in 161 genotyped subjects (97 genetically affected, 64 unaffected) from 20 families with disease-causing mutations in 4 genes. The diagnostic value of 4 voltage criteria (Cornell, Sokolow-Lyon, Romhilt-Estes, and 12-lead QRS voltage) for detecting carriers of HC was investigated. In all subjects, the Romhilt-Estes (point score > or =4) criterion and 12-lead QRS voltage (> or =240 mm) were most sensitive (37% and 36%, respectively), with high specificity (95% each), resulting in the greatest accuracy (60% and 59%, respectively). Using these criteria, in subjects without echocardiographic evidence of left ventricular hypertrophy, voltage abnormalities were found in 22.6% of carriers and 4.7% of noncarriers (p <0.01). In conclusion, these findings suggest that the Romhilt-Estes and the 12-lead QRS voltage criteria may be the most accurate diagnostic definitions for HC on the basis of molecular genetic diagnoses. Furthermore, this study demonstrated that voltage abnormalities may be found in prehypertrophic carriers. Even when genetic testing becomes widely available, it will be difficult to make genetic diagnoses in all patients with HC because of its genetic heterogeneity. Therefore, understanding the diagnostic value of classic ECG voltage criteria may be important in detecting carriers, including those without left ventricular hypertrophy.
Collapse
Affiliation(s)
- Tetsuo Konno
- Molecular Genetics of Cardiovascular Disorders, Division of Cardiovascular Medicine, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Konno T, Shimizu M, Ino H, Fujino N, Hayashi K, Uchiyama K, Kaneda T, Inoue M, Masuda E, Mabuchi H. Phenotypic differences between electrocardiographic and echocardiographic determination of hypertrophic cardiomyopathy in genetically affected subjects. J Intern Med 2005; 258:216-24. [PMID: 16115294 DOI: 10.1111/j.1365-2796.2005.01539.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES In the molecular era, two types of phenotypic differences are recognized between electrocardiography (ECG) and echocardiography in hypertrophic cardiomyopathy (HCM); ECG abnormalities in carriers without left ventricular hypertrophy (LVH), and normal ECG patterns in carriers with LVH. The goal of this study was to evaluate the diagnostic value of ECG for detecting carriers without LVH, and also to assess normal ECG patterns in carriers with LVH from the genetic standpoint of HCM. SETTING A matched case-control study in a university hospital and general hospitals in Japan. PATIENTS AND DESIGN ECG and echocardiographic findings were analysed in 173 genotyped subjects (107 genetically affected, 66 unaffected) from families with disease-causing mutations in four genes. RESULTS ECG abnormalities were found in 18 (54.5%) of 33 nonhypertrophic carriers, but only nine (13.6%) of 66 noncarriers (P < 0.001). For detecting nonhypertrophic carriers, ST-T abnormalities showed the highest accuracy amongst the three major ECG criteria. In contrast, normal ECG patterns were found in eight (10.8%) of 74 carriers with LVH. The sensitivity of ECG for detecting carriers with LVH in families with the cardiac myosin-binding protein C, cardiac troponin T and cardiac troponin I gene mutations was 83%, 88% and 94% respectively. CONCLUSION These findings suggest that ECG may have favourable diagnostic value even for detecting nonhypertrophic carriers. Furthermore, diagnostic value of ECG may differ according to the genes involved. Our data may contribute to interpretation of phenotypic differences between ECG and echocardiography from the viewpoint of molecular genetics of HCM.
Collapse
Affiliation(s)
- T Konno
- Molecular Genetics of Cardiovascular Disorders, Division of Cardiovascular Medicine, Graduate School of Medical Science, Kanazawa University, Takara-machi 13-1, Kanazawa, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Wang P, Zou Y, Fu C, Zhou X, Hui R. MYBPC3 polymorphism is a modifier for expression of cardiac hypertrophy in patients with hypertrophic cardiomyopathy. Biochem Biophys Res Commun 2005; 329:796-9. [PMID: 15737656 DOI: 10.1016/j.bbrc.2005.02.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Indexed: 10/25/2022]
Abstract
Clinical phenotype of hypertrophic cardiomyopathy exhibits significant inter- and intra-familial heterogeneities. To test if MYBPC3 polymorphism could modify the expression of cardiac hypertrophy, 226 patients with hypertrophic cardiomyopathy and 226 age- and sex-matched controls were recruited according to the diagnostic criteria of WHO. Genotyping was completed by using PCR, restrictive enzyme digestion, and sequencing. Three polymorphisms of MYBPC3 were studied, only the GG genotype at 18443 in exon 30 associated with thicker left ventricular wall (25.2+/-5.9 mm) in patient group, not the AA and AG genotypes (19.0+/-5.0mm, P<0.001). After multiple regression analysis for adjustment of age and sex, the association remained. No difference was found in the genotype distribution between control and patients. Our results point out that GG genotype of MYBPC3 might be a genetic risk factor for the expression of cardiac hypertrophic phenotype in the patients with hypertrophic cardiomyopathy.
Collapse
MESH Headings
- Cardiomyopathy, Hypertrophic, Familial/diagnostic imaging
- Cardiomyopathy, Hypertrophic, Familial/epidemiology
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/metabolism
- Carrier Proteins/genetics
- Causality
- China/epidemiology
- Comorbidity
- DNA Mutational Analysis/methods
- Female
- Genetic Predisposition to Disease/epidemiology
- Genetic Testing/methods
- Genetic Variation
- Humans
- Male
- Middle Aged
- Polymorphism, Genetic
- Prevalence
- Risk Assessment/methods
- Risk Factors
- Severity of Illness Index
- Single-Blind Method
- Ultrasonography
- Ventricular Dysfunction, Left/diagnostic imaging
- Ventricular Dysfunction, Left/epidemiology
- Ventricular Dysfunction, Left/genetics
- Ventricular Dysfunction, Left/metabolism
Collapse
Affiliation(s)
- Ping Wang
- Sino-German Laboratory for Molecular Medicine, Department of Cardiology, FuWai Hospital, Chinese Academy of Medical Sciences, Beijing, China
| | | | | | | | | |
Collapse
|
22
|
Blair E, Price SJ, Baty CJ, Ostman-Smith I, Watkins H. Mutations in cis can confound genotype-phenotype correlations in hypertrophic cardiomyopathy. J Med Genet 2001; 38:385-8. [PMID: 11424919 PMCID: PMC1734887 DOI: 10.1136/jmg.38.6.385] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
23
|
Abstract
Myosin heavy chain (MyHC) is a critical component of the cellular contractile apparatus. The mammalian genome contains two nonmuscle, two smooth muscle, and eight striated muscle isoforms of MyHC. Within each class of genes, there is extremely high sequence homology among different MyHC isoforms, raising the question of whether these isoforms are functionally redundant or whether they perform unique roles in cell function. Recently, strains of mice null for four different MyHC isoforms have been generated. Mice null for the nonmuscle II-B isoform experience significant prenatal lethality and surviving animals have several cardiac abnormalities [Tullio et al. (1997) Proc Natl Acad Sci USA 94:12407-12412]. Mice homozygous null for alpha cardiac MyHC are embryonic lethal, while heterozygous mice are viable but also have numerous cardiac defects [Jones et al. (1996) J Clin Invest 98:1906-1917]. Mice null for IIb or IId adult skeletal MyHC are viable but have skeletal muscle abnormalities compared to wild type mice, despite compensation of a neighboring MyHC gene [Acakpo-Satchivi et al. (1997) J Cell Biol 139:1219-1229]. Both IIb and IId null mice show significant decreases in body mass. Mean muscle mass is also significantly decreased in both null strains but the extent and the pattern of affected muscles differs between the two strains. Both strains show evidence of skeletal muscle pathology but again the pattern and extent differ between the two strains. Finally, both adult skeletal strains demonstrate distinct impairments in contractile function when compared to wild type. Together these observations support the hypothesis that the different isoforms of MyHC are functionally unique and cannot substitute for one another.
Collapse
Affiliation(s)
- D L Allen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado 80309-0347, USA
| | | | | |
Collapse
|
24
|
Richard P, Charron P, Leclercq C, Ledeuil C, Carrier L, Dubourg O, Desnos M, Bouhour JB, Schwartz K, Daubert JC, Komajda M, Hainque B. Homozygotes for a R869G mutation in the beta -myosin heavy chain gene have a severe form of familial hypertrophic cardiomyopathy. J Mol Cell Cardiol 2000; 32:1575-83. [PMID: 10900182 DOI: 10.1006/jmcc.2000.1193] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
UNLABELLED Familial Hypertrophic Cardiomyopathy (FHC) is an autosomal dominant disease characterised by ventricular hypertrophy, with predominant involvement of the interventricular septum. It is a monogenic disease with a high level of genetic heterogeneity (nine genes and more than 110 mutations reported so far). We describe a family with a new R869G mutation in the beta -myosin heavy chain gene (MYH7). This mutation was found in the heterozygous status in both parents and in the homozygous status in the two children. A haplotype analysis on the MYH7 locus with microsatellite markers showed that the same haplotype is transmitted within the family, suggesting a founder effect. Clinically, the father was asymptomatic with mild left ventricular hypertrophy on echocardiography. The mother had a mild form of hypertrophic cardiomyopathy and remained asymptomatic until 60 years old when an atrial fibrillation occurred. For the two children, clinical diagnosis was performed at 12 and 8 years and atrial fibrillation occurred at 17 years. For both children, the evolution was characterized by left ventricle (LV) systolic dysfunction and a severe dilatation of the left atrium before 40 years of age. CONCLUSIONS In this family, a new R869G mutation in the MYH7 gene was found. Interestingly, a mutation was found at the homozygous status for the first time in FHC. This finding suggests that this particular mutation is compatible with life, but for homozygous subjects, age at onset of symptoms was earlier and the disease much more severe than in the heterozygous subjects, suggesting a gene-dose effect.
Collapse
Affiliation(s)
- P Richard
- Service de Biochimie B, Hôpital de la Salpêtrière, Paris, France
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Muraishi A, Kai H, Adachi K, Nishi H, Imaizumi T. Malalignment of the sarcomeric filaments in hypertrophic cardiomyopathy with cardiac myosin heavy chain gene mutation. Heart 1999; 82:625-9. [PMID: 10525522 PMCID: PMC1760777 DOI: 10.1136/hrt.82.5.625] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE To investigate changes in the alignment of the sarcomeric filaments in hypertrophic cardiomyopathy and the effects of cardiac beta myosin heavy chain (beta-MHC) mutation on the sarcomeric ultrastructure. DESIGN A retrospective analysis. PATIENTS Endomyocardial biopsy samples were examined by transmission electron microscopy in seven patients with hypertrophic cardiomyopathy and beta-MHC mutation, six with hypertrophic cardiomyopathy but without the mutation, and five controls (with chest pain syndromes). MAIN OUTCOME MEASURE Alignment of the sarcomeric filaments and the distance between neighbouring thick myosin filaments. RESULTS In controls, cross sections of the sarcomere at the A band showed a highly organised orthohexagonal array with 6 thin actin filaments surrounding one thick myosin filament, whereas in hypertrophic cardiomyopathy the alignment of the sarcomeric filaments was sparse and disrupted. In hypertrophic cardiomyopathy with a mutation, the distance between neighbouring thick myosin filaments was greater than in controls (mean (SD) 45.3 (4.7) v 38.5 (3.5) nm, p < 0.05), and the variance of the distance was greater than in controls (8.0 (0.7) v 4.8 (1.0) nm, p < 0.001) or in patients with hypertrophic cardiomyopathy without a mutation (6.7 (0.6) nm, p < 0.05). In the latter, the variance of the distance was also greater than in the controls (p < 0.01). A significant correlation was found between the grade of the myocyte hypertrophy and the variance of the distance (r = 0.654; p < 0.01). CONCLUSIONS The alignment of the sarcomeric filaments is disrupted in hypertrophic cardiomyopathy, particularly when there is beta-MHC mutation.
Collapse
Affiliation(s)
- A Muraishi
- The Third Department of Internal Medicine, Kurume University School of Medicine, 67 Asahi-machi, Kurume, Fukuoka 830-0011, Japan
| | | | | | | | | |
Collapse
|
26
|
Escobar-Morreale HF, San Millán JL, Smith RR, Sancho J, Witchel SF. The presence of the 21-hydroxylase deficiency carrier status in hirsute women: phenotype-genotype correlations. Fertil Steril 1999; 72:629-38. [PMID: 10521100 DOI: 10.1016/s0015-0282(99)00317-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To determine the role of heterozygosity for mutations in the 21-hydroxylase gene (CYP21) in the pathogenesis of hyperandrogenism. DESIGN Controlled clinical study. SETTING Tertiary care institutional hospital. PATIENT(S) Forty hirsute women and 13 healthy control women. INTERVENTION(S) The source of androgen excess was determined by the changes in serum testosterone levels in response to a single 3.75-mg i.m. dose of triptorelin. MAIN OUTCOME MEASURE(S) CYP21 molecular genetic analysis and serum 17-hydroxyprogesterone levels. RESULT(S) Eight patients and one control were heterozygous carriers of CYP21 mutations. Two patients with adrenal hyperandrogenism and one patient with ovarian hyperandrogenism, who carried the V281L mutation had an increased ACTH-stimulated 17-hydroxyprogesterone level (>4.1 ng/mL) that persisted during gonadal suppression. Another patient with adrenal hyperandrogenism carried the V281L mutation, and her ACTH-stimulated 17-hydroxyprogesterone level was elevated only during gonadal suppression. Four patients (three with idiopathic hirsutism, one with ovarian hyperandrogenism) and one control were carriers of CYP21 mutations typically associated with classic congenital adrenal hyperplasia but had normal basal and ACTH-stimulated 17-hydroxyprogesterone levels. Nine patients without CYP21 mutations had increased ACTH-stimulated 17-hydroxyprogesterone levels; these decreased to normal in six of the patients during gonadal suppression. CONCLUSION(S) The response of serum 17-hydroxyprogesterone to ACTH does not predict CYP21 carrier status. No clear concordance was found between the CYP21 genotype and the functional origin of androgen excess.
Collapse
|
27
|
Richard P, Isnard R, Carrier L, Dubourg O, Donatien Y, Mathieu B, Bonne G, Gary F, Charron P, Hagege A, Komajda M, Schwartz K, Hainque B. Double heterozygosity for mutations in the β-myosin heavy chain and in the cardiac myosin binding protein C genes in a family with hypertrophic cardiomyopathy. J Med Genet 1999. [DOI: 10.1136/jmg.36.7.542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Familial hypertrophic cardiomyopathy is a genetically heterogeneous autosomal dominant disease, caused by mutations in several sarcomeric protein genes. So far, seven genes have been shown to be associated with the disease with the β-myosin heavy chain (MYH7) and the cardiac myosin binding protein C (MYBPC3) genes being the most frequently involved.We performed electrocardiography (ECG) and echocardiography in 15 subjects with hypertrophic cardiomyopathy from a French Caribbean family. Genetic analyses were performed on genomic DNA by haplotype analysis with microsatellite markers at each locus involved and mutation screening by single strand conformation polymorphism analysis. Based on ECG and echocardiography, eight subjects were affected and presented a classical phenotype of hypertrophic cardiomyopathy. Two new mutations cosegregating with the disease were found, one located in the MYH7 gene exon 15 (Glu483Lys) and the other in the MYBPC3 gene exon 30 (Glu1096 termination codon). Four affected subjects carried the MYH7 gene mutation, two the MYBPC3 gene mutation, and two were doubly heterozygous for the two mutations. The doubly heterozygous patients exhibited marked left ventricular hypertrophy, which was significantly greater than in the other affected subjects.We report for the first time the simultaneous presence of two pathological mutations in two different genes in the context of familial hypertrophic cardiomyopathy. This double heterozygosity is not lethal but is associated with a more severe phenotype.
Collapse
|
28
|
Hwang TH, Lee WH, Kimura A, Satoh M, Nakamura T, Kim MK, Choi SK, Park JE. Early expression of a malignant phenotype of familial hypertrophic cardiomyopathy associated with a Gly716Arg myosin heavy chain mutation in a Korean family. Am J Cardiol 1998; 82:1509-13. [PMID: 9874056 DOI: 10.1016/s0002-9149(98)00695-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The clinical course and prognosis of familial hypertrophic cardiomyopathy (HCM) are different according to the type of mutation in the genes for sarcomere proteins. It has been disputed that a mutation, which occurs at a functionally important region in the sarcomere proteins, may increase the penetrance and expressivity of the disease. We searched for a causative mutation in an HCM family, which is characterized by early expression of clinical phenotype, high incidence of sudden death at young ages, and progressive heart failure in adults. Among the 32 family members in 4 generations, 13 were affected; 4 died suddenly before age 16, 2 children have already had full expression of the cardiac hypertrophy, and other adults have either progressive heart failure or poor left ventricular systolic functions. PCR-SSCP (polymerase chain reaction-single strand confirmation polymorphism) analysis of genomic DNAs isolated from peripheral blood leukocytes of the family members identified a Gly716Arg mutation in the cardiac beta-myosin heavy chain gene, which was cosegregated with the clinical phenotype. The mutation is localized near a functionally important site of the myosin heavy chain, the 2 active thiols, which contribute to the adenosine triphosphatase activity of myosin S1. This family provides further evidence that the mutation, which occurs at a functionally important site of the myosin heavy chain, is associated with the high penetrance and early expression of HCM.
Collapse
Affiliation(s)
- T H Hwang
- Samsung Biomedical Research Institute, Seoul, Korea
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Vosberg HP. [Genetic causes of hypertrophic cardiomyopathy]. MEDIZINISCHE KLINIK (MUNICH, GERMANY : 1983) 1998; 93:252-9. [PMID: 9594535 DOI: 10.1007/bf03044801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hypertrophic cardiomyopathy is a dominantly inherited disease of the heart. Heterogeneous sets of mutations responsible for this condition have been identified in seven genes coding for proteins involved in the contraction mechanism or in the control of contraction of the myocardium. Known mutations imply structural and functional changes in the following proteins: in ventricle specific beta-myosin heavy chain, in essential and regulatory myosin light chains, in troponin subunits T and I, in alpha-tropomyosin and in myosin binding protein-C. The gene of one additional genomic HCM-locus is not known. Since two thirds or more of all cases can be traced to one of the respective genes, HCM has been classified as a disease of the cardiac sarcomere. Heterogeneity does not only exist between genes, but also within genes. At least 84 different mutations have been identified to date. More than half of them have been detected in the beta-myosin heavy chain gene. Thus, mutations in this gene account for most of the cases of HCM. The extent of data about causes is in contrast to the lack of definite knowledge about pathogenic mechanisms. Since the disorder is in many cases mild with symptoms developing frequently not before the end of the second decade, myocardial dysfunctions can presumably not directly be traced to altered contractility, but rather to effects which accumulate with a long asymptomatic lag period and which gradually lead to hypertrophy, conduction problems and ultimately to cardiac failure. The disease may be considered as an indirect and secondary response to a mildly distorted contraction process. The rapid progress in the analysis of causes suggests that the study of genes will assume a role in the context of the clinical management of HCM, in particular regarding diagnosis, prognosis, counselling of patients and families and--possibly--therapy.
Collapse
Affiliation(s)
- H P Vosberg
- Max-Planck-Institut für physiologische und klinische Forschung, Abteilung Experimentelle Kardiologie, Bad Nauheim.
| |
Collapse
|
30
|
Kimura A, Harada H, Park JE, Nishi H, Satoh M, Takahashi M, Hiroi S, Sasaoka T, Ohbuchi N, Nakamura T, Koyanagi T, Hwang TH, Choo JA, Chung KS, Hasegawa A, Nagai R, Okazaki O, Nakamura H, Matsuzaki M, Sakamoto T, Toshima H, Koga Y, Imaizumi T, Sasazuki T. Mutations in the cardiac troponin I gene associated with hypertrophic cardiomyopathy. Nat Genet 1997; 16:379-82. [PMID: 9241277 DOI: 10.1038/ng0897-379] [Citation(s) in RCA: 363] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Hypertrophic cardiomyopathy (HCM), the most common cause of sudden death in the young, is an autosomal dominant disease characterized by ventricular hypertrophy accompanied by myofibrillar disarrays. Linkage studies and candidate-gene approaches have demonstrated that about half of the patients have mutations in one of six disease genes: cardiac beta-myosin heavy chain (c beta MHC), cardiac troponin T (cTnT), alpha-tropomyosin (alpha TM), cardiac myosin binding protein C (cMBPC), ventricular myosin essential light chain (vMLC1) and ventricular myosin regulatory light chain (vMLC2) genes. Other disease genes remain unknown. Because all the known disease genes encode major contractile elements in cardiac muscle, we have systematically characterized the cardiac sarcomere genes, including cardiac troponin I (cTnI), cardiac actin (cACT) and cardiac troponin C (cTnC) in 184 unrelated patients with HCM and found mutations in the cTnI gene in several patients. Family studies showed that an Arg145Gly mutation was linked to HCM and a Lys206Gln mutation had occurred de novo, thus strongly suggesting that cTnI is the seventh HCM gene.
Collapse
Affiliation(s)
- A Kimura
- Department of Tissue Physiology, Tokyo Medical and Dental University, Japan.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Ishanov A, Okamoto H, Yoneya K, Watanabe M, Nakagawa I, Machida M, Onozuka H, Mikami T, Kawaguchi H, Hata A, Kondo K, Kitabatake A. Angiotensinogen gene polymorphism in Japanese patients with hypertrophic cardiomyopathy. Am Heart J 1997; 133:184-9. [PMID: 9023164 DOI: 10.1016/s0002-8703(97)70207-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
To examine the contribution of the renin-angiotensin system to hypertrophic cardiomyopathy (HCM), we studied 96 patients with HCM (mean age 50 years, 55% male), 105 of their unaffected siblings and offspring, and 160 healthy subjects without known hypertension and left ventricular hypertrophy (LVH) who were frequency matched to cases by age and sex. Patients were divided into familial or sporadic HCM (FHCM or SHCM) groups with or without affected members of their family. The region of interest in the angiotensinogen (AGT) gene, the missense mutation with methione-to-threonine amino acid substitution at codon 235 in angiotensinogen (M235T), was amplified by polymerase chain reaction with the use of allele-specific oligonucleotide primers flanking the polymorphic region of the AGT gene to amplify template deoxyribonucleic acid prepared from peripheral leukocytes. The T allele frequency was higher in the SHCM group than in unaffected siblings and offspring (88% vs 78%, X2 = 4.6, p < 0.05). The M allele frequency was higher in unaffected siblings and offspring than in patients with SHCM (23% vs 12%, X2 = 4.6, p < 0.05). The T allele frequency among unaffected siblings and offspring was similar to that observed in healthy subjects (78% vs 78%). We conclude that HCM, especially in sporadic cases, is partially determined by genetic disposition. The molecular variant of angiotensinogen T235 seems to be a predisposing factor for cardiac hypertrophy in HCM and carries an approximately twofold increased risk.
Collapse
Affiliation(s)
- A Ishanov
- Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Kita-ku, Sapporo, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Koga Y, Toshima H, Kimura A, Harada H, Koyanagi T, Nishi H, Nakata M, Imaizumi T. Clinical manifestations of hypertrophic cardiomyopathy with mutations in the cardiac beta-myosin heavy chain gene or cardiac troponin T gene. J Card Fail 1996; 2:S97-103. [PMID: 8951566 DOI: 10.1016/s1071-9164(96)80064-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Introduction of molecular genetics has improved our understanding of HCM substantially, but has simultaneously raised further important questions. Studies on HCM are revealing a more complex picture than might have been expected on clinical grounds. Further extensive studies are warranted to elucidate the pathogenesis and pathophysiology of HCM, and to establish therapeutic strategies to cure or prevent the development of the disease.
Collapse
Affiliation(s)
- Y Koga
- Kurume University Medical Center, Fukuoka, Japan
| | | | | | | | | | | | | | | |
Collapse
|
33
|
Watkins H, Seidman CE, Seidman JG, Feng HS, Sweeney HL. Expression and functional assessment of a truncated cardiac troponin T that causes hypertrophic cardiomyopathy. Evidence for a dominant negative action. J Clin Invest 1996; 98:2456-61. [PMID: 8958207 PMCID: PMC507702 DOI: 10.1172/jci119063] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Mutations in the beta-myosin heavy chain gene are believed to cause hypertrophic cardiomyopathy (HCM) by acting as dominant negative alleles. In contrast, a truncated cardiac troponin T (TnT) that causes HCM implies that altered stoichiometry of contractile proteins may also cause cardiac hypertrophy. Wild-type and HCM-mutant (truncated) TnT were studied in a novel quail myotube expression system. Unexpectedly, antibody staining demonstrated incorporation of both forms of human cardiac TnT into the sarcomeres of quail myotubes. Functional studies of wild type and mutant transfected myotubes of normal appearance revealed that calcium-activated force of contraction was normal upon incorporation of wild type TnT, but greatly diminished for the mutant TnT. These findings indicate that HCM-causing mutations in TnT and beta-myosin heavy chain share abnormalities in common, acting as dominant negative alleles that impair contractile performance. This diminished force output is the likely stimulus for hypertrophy in the human heart.
Collapse
Affiliation(s)
- H Watkins
- Department of Cardiovascular Medicine, University of Oxford, United Kingdom
| | | | | | | | | |
Collapse
|
34
|
Posma JL, van der Wall EE, Blanksma PK, van der Wall E, Lie KI. New diagnostic options in hypertrophic cardiomyopathy. Am Heart J 1996; 132:1031-41. [PMID: 8892780 DOI: 10.1016/s0002-8703(96)90018-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The pathophysiologic features and clinical manifestations of HCM have been elucidated by the introduction of several new diagnostic options. Knowledge of the molecular defects of HCM has advanced rapidly, and genetic screening studies have reemphasized the value of the standard electrocardiogram as an initial screening tool. Analysis of heart rate variability, late potentials, and QT dispersion were not found to be reliable prognostic markers in HCM. However, measurement of dispersion of conduction is probably a sensitive technique in identifying a high risk for sudden cardiac death. Significant developments include transthoracic and transesophageal echocardiography and their role in studying the mitral valve, early detection of left ventricular chamber dilatation, analysis of coronary flow, and intraoperative echocardiography. Finally, advances in the application of magnetic resonance imaging and positron-emission tomography are underway.
Collapse
Affiliation(s)
- J L Posma
- Department of Cardiology, Thoraxcenter, University Hospital Groningen, The Netherlands
| | | | | | | | | |
Collapse
|
35
|
Abstract
Mutations in several muscle structural proteins (the myosin heavy chain, alpha tropomyosin, cardiac troponin T and myosin binding protein C) result in a genetically dominant heart disease, hypertrophic cardiomyopathy. Biochemical data from studies of mutant myosin suggest a dominant-negative mechanism for inheritance of this disease. The most likely primary defect is sarcomere dysfunction, which is followed by the major clinical symptoms.
Collapse
Affiliation(s)
- K L Vikstrom
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder 80309-0347, USA.
| | | |
Collapse
|