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Del Duca F, Ghamlouch A, Manetti AC, Napoletano G, Sonnini E, Treves B, De Matteis A, La Russa R, Sheppard MN, Fineschi V, Maiese A. Sudden Cardiac Death, Post-Mortem Investigation: A Proposing Panel of First Line and Second Line Genetic Tests. J Pers Med 2024; 14:544. [PMID: 38793126 PMCID: PMC11122432 DOI: 10.3390/jpm14050544] [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: 04/15/2024] [Revised: 05/02/2024] [Accepted: 05/16/2024] [Indexed: 05/26/2024] Open
Abstract
Investigating the causes of Sudden cardiac death (SCD) is always difficult; in fact, genetic cardiac conditions associated with SCD could be "silent" even during autopsy investigation. In these cases, it is important to exclude other aetiology and assist to ask for genetic investigations. Herein, the purpose of this review is to collect the most-implicated genes in SCD and generate a panel with indications for first line and second line investigations. A systematic review of genetic disorders that may cause SCD in the general population was carried out according to the Preferred Reporting Item for Systematic Review (PRISMA) standards. We subsequently listed the genes that may be tested in the case of sudden cardiac death when the autopsy results are negative or with no evidence of acquired cardiac conditions. To make genetic tests more specific and efficient, it is useful and demanded to corroborate autopsy findings with the molecular investigation as evident in the panel proposed. The genes for first line investigations are HCM, MYBPC3, MYH7, TNNT2, TNNI3, while in case of DCM, the most implicated genes are LMNA and TTN, and in second line for these CDM, ACTN2, TPM1, C1QPB could be investigated. In cases of ACM/ARVC, the molecular investigation includes DSP, DSG2, DSC2, RYR2, PKP2. The channelopathies are associated with the following genes: SCN5A, KCNQ1, KCNH2, KCNE1, RYR2. Our work underlines the importance of genetic tests in forensic medicine and clinical pathology; moreover, it could be helpful not only to assist the pathologists to reach a diagnosis, but also to prevent other cases of SCD in the family of the descendant and to standardise the type of analysis performed in similar cases worldwide.
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Affiliation(s)
- Fabio Del Duca
- Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Viale Regina Elena 336, 00161 Rome, Italy; (F.D.D.); (A.G.); (G.N.); (B.T.); (A.D.M.); (V.F.)
| | - Alessandro Ghamlouch
- Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Viale Regina Elena 336, 00161 Rome, Italy; (F.D.D.); (A.G.); (G.N.); (B.T.); (A.D.M.); (V.F.)
| | - Alice Chiara Manetti
- Department of Public Health and Infectious Diseases, Sapienza University of Rome, 00168 Rome, Italy;
| | - Gabriele Napoletano
- Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Viale Regina Elena 336, 00161 Rome, Italy; (F.D.D.); (A.G.); (G.N.); (B.T.); (A.D.M.); (V.F.)
| | - Elena Sonnini
- Medicina Genomica, Dipartimento Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy;
| | - Biancamaria Treves
- Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Viale Regina Elena 336, 00161 Rome, Italy; (F.D.D.); (A.G.); (G.N.); (B.T.); (A.D.M.); (V.F.)
| | - Alessandra De Matteis
- Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Viale Regina Elena 336, 00161 Rome, Italy; (F.D.D.); (A.G.); (G.N.); (B.T.); (A.D.M.); (V.F.)
| | - Raffaele La Russa
- Department of Clinical Medicine, Public Health, Life Sciences, and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy
| | - Mary N. Sheppard
- Department of Cardiovascular Pathology, Level 1, Jenner Wing Corridor 4, St George’s University of London, Cranmer Terrace, London SW17 0RE, UK;
| | - Vittorio Fineschi
- Department of Anatomical, Histological, Forensic and Orthopedic Sciences, Sapienza University of Rome, Viale Regina Elena 336, 00161 Rome, Italy; (F.D.D.); (A.G.); (G.N.); (B.T.); (A.D.M.); (V.F.)
| | - Aniello Maiese
- Department of Surgical Pathology, Medical, Molecular and Critical Area, Institute of Legal Medicine, University of Pisa, 56126 Pisa, Italy
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Kumar P, Paramasivam G, Devasia T, Prabhu M, Rai MK, Prakashini K, Mallya S, Reghunathan D, Megha A, Nayak K, Moka R. A Novel TPM1 Mutation Causes Familial Hypertrophic Cardiomyopathy in an Indian Family: Genetic and Clinical Correlation. Indian J Clin Biochem 2024; 39:142-145. [PMID: 38223010 PMCID: PMC10784234 DOI: 10.1007/s12291-022-01036-w] [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: 09/30/2021] [Accepted: 02/21/2022] [Indexed: 11/26/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is a common inherited cardiac disorder characterised by unexplained left ventricular hypertrophy in the absence of abnormal loading conditions. The global prevalence of HCM is estimated to be 1 in 250 in the general population. It is caused due to mutations in genes coding for sarcomeric proteins. α-tropomyosin (TPM1) is an important protein in the sarcomeric thin filament which regulates sarcomere contraction. Mutations in TPM1 are known to cause hypertrophic cardiomyopathy, dilated cardiomyopathy and left ventricular non-compaction. Mutations in TPM1 causing hypertrophic cardiomyopathy are < 1%. However, some high-risk mutations causing sudden cardiac death are also known in this gene. We present a case of a novel heterozygous TPM1 mutation, NM_001018005.2:c.203A>G, p.Gln68Arg; co-segregating in an Indian family with hypertrophic cardiomyopathy. Our report expands the mutational spectrum of HCM due to TPM1 and provides the correlated cardiac phenotype.
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Affiliation(s)
- Prabodh Kumar
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Planetarium Complex, Madhav Nagar, Manipal, 576104 Karnataka India
| | - Ganesh Paramasivam
- Department of Cardiology, Kasturba Medical College, Manipal Academy of Higher Education (MAHE), Manipal, 576104 Karnataka India
| | - Tom Devasia
- Department of Cardiology, Kasturba Medical College, Manipal Academy of Higher Education (MAHE), Manipal, 576104 Karnataka India
| | - Mukund Prabhu
- Department of Cardiology, Kasturba Medical College, Manipal Academy of Higher Education (MAHE), Manipal, 576104 Karnataka India
| | - Maneesh K. Rai
- Department of Cardiology, Kasturba Medical College, Manipal Academy of Higher Education (MAHE), Mangalore, 575001 Karnataka India
| | - K. Prakashini
- Department of Radiodiagnosis and Imaging, Kasturba Medical College, Manipal Academy of Higher Education (MAHE), Manipal, 576104 Karnataka India
| | - Sandeep Mallya
- Department of Bioinformatics, Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Manipal, 576104 Karnataka India
| | - Dinesh Reghunathan
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Planetarium Complex, Madhav Nagar, Manipal, 576104 Karnataka India
| | - A. Megha
- Department of Cardiovascular Technology, Manipal College of Health Profession, Manipal Academy of Higher Education (Manipal), Manipal, 576104 Karnataka India
| | - Krishnananda Nayak
- Department of Cardiovascular Technology, Manipal College of Health Profession, Manipal Academy of Higher Education (Manipal), Manipal, 576104 Karnataka India
| | - Rajasekhar Moka
- Department of Cell and Molecular Biology, Manipal School of Life Sciences, Manipal Academy of Higher Education (MAHE), Planetarium Complex, Madhav Nagar, Manipal, 576104 Karnataka India
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Lamounier Junior A, Guitián González A, Rodríguez Vilela A, Repáraz Andrade A, Rubio Alcaide Á, Berta Sousa A, Benito López C, Alonso García D, Fernández Ferro G, Cruz I, Cárdenas Reyes IJ, Salazar-Mendiguchía García J, Larrañaga-Moreira JM, Ochoa JP, Palomino-Doza J, de la Higuera Romero L, Nicolás Cicerchia M, Restrepo Córdoba MA, Peña-Peña ML, Noël Brögger M, Loureiro M, Mogollón Jiménez MV, Bilbao Quesada R, Franco Gutiérrez R, García Hernández S, Ripoll-Vera T, Fernández X, Azevedo O, García Pavía P, Lopes LR, Ortiz M, Brito D, Barriales-Villa R, Monserrat Iglesias L. Correlación genotipo-fenotipo en miocardiopatía hipertrófica: un estudio multicéntrico en Portugal y España sobre la variante p.Arg21Leu de TPM1. Rev Esp Cardiol 2022. [DOI: 10.1016/j.recesp.2020.12.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Li X, Tang J, Li J, Lin S, Wang T, Zhou K, Li Y, Hua Y. Genetic Clues on Implantable Cardioverter-Defibrillator Placement in Young-Age Hypertrophic Cardiomyopathy: A Case Report of Novel MYH7 Mutation and Literature Review. Front Cardiovasc Med 2022; 8:810291. [PMID: 35004917 PMCID: PMC8733160 DOI: 10.3389/fcvm.2021.810291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Hypertrophic cardiomyopathy (HCM) is the second most common cardiomyopathy in childhood with a life-threatening risk. Implantable cardioverter-defibrillator (ICD) placement is recommended for early prevention if there are two or more clinical risk factors. Pediatric patients with HCM are at a higher risk of sudden cardiac death (SCD), but there are limited reports on indications for ICD implantation in children. Herein we describe the case of Myh7 mutation-induced HCM and cardiac arrest in a patient and evaluated information originating from genetic background to guide ICD administration. Case Presentation: The patient was a girl aged 7 years and 8 months who had been diagnosed with cardiomyopathy in utero 8 years prior. She had had recurrent cardiac arrests within the last 4 years. Electrocardiography indicated abnormalities in conduction, and ST segment changes. Echocardiography indicated significant left ventricular hypertrophy and hypertrophic systolic interventricular septum. Cardiac magnetic resonance imaging depicted general heart enlargement with hypertrophy, and delayed enhancement in myocardium with perfusion defect was also evident. Whole exon sequencing identified a de novo c.2723T>C (p.L908P) heterozygous mutation in the MYH7 gene. MYH7 p.L908P predicted unstable protein structure and impaired function. The patient was scheduled for ICD implantation. There were no complications after ICD implantation, and she was discharged from hospital on the 10th day. Regular oral beta-blockers, amiodarone, spironolactone, and enalapril were administered, and she was required to attend hospital regularly for follow-up. During follow-up there were no cardiac arrests. Literature review of clinical prognoses associated with genetic mutations of MYH7, MYBPC3, TNNI3, TNNT2, and TPM1 in pediatric HCM patients with and without ICD implantation indicated that they were totally differently. Previous reports also indicated that gene mutations predicted earlier onset of cardiac hypertrophy, and increase likelihood of SCD. Conclusion: Variant burden and variant type contribute to the risk of adverse events in pediatric HCM. Early recognition and intervention are vital in children. Gene mutation could be considered an indication for early ICD placement during standard risk stratification of HCM patients. Whether this extends to the majority of pediatric patients requires further investigation.
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Affiliation(s)
- Xing Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Jie Tang
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Jinhui Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Sha Lin
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Tao Wang
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Kaiyu Zhou
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yifei Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Yimin Hua
- Key Laboratory of Birth Defects and Related Diseases of Women and Children of Ministry of Education, Department of Pediatrics, West China Second University Hospital, Sichuan University, Chengdu, China
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Genotype-phenotype correlations in hypertrophic cardiomyopathy: a multicenter study in Portugal and Spain of the TPM1 p.Arg21Leu variant. ACTA ACUST UNITED AC 2021; 75:242-250. [PMID: 33642254 DOI: 10.1016/j.rec.2021.01.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 12/18/2020] [Indexed: 11/23/2022]
Abstract
INTRODUCTION AND OBJECTIVES TPM1 is one of the main hypertrophic cardiomyopathy (HCM) genes. Clinical information on carriers is relatively scarce, limiting the interpretation of genetic findings in individual patients. Our aim was to establish genotype-phenotype correlations of the TPM1 p.Arg21Leu variant in a serie of pedigrees. METHODS TPM1 was evaluated by next-generation sequencing in 10 561 unrelated probands with inherited heart diseases. Familial genetic screening was performed by the Sanger method. We analyzed TPM1 p.Arg21Leu pedigrees for cosegregation, clinical characteristics, and outcomes. We also estimated the geographical distribution of the carrier families in Portugal and Spain. RESULTS The TPM1 p.Arg21Leu variant was identified in 25/4099 (0.61%) HCM-cases, and was absent in 6462 control individuals with other inherited cardiac phenotypes (P<.0001). In total, 83 carriers (31 probands) were identified. The combined LOD score for familial cosegregation was 3.95. The cumulative probability of diagnosis in carriers was 50% at the age of 50 years for males, and was 25% in female carriers. At the age of 70 years, 17% of males and 46% of female carriers were unaffected. Mean maximal left ventricular wall thickness was 21.4 ±7.65mm. Calculated HCM sudden death risk was low in 34 carriers (77.5%), intermediated in 8 (18%), and high in only 2 (4.5%). Survival free of cardiovascular death or heart transplant was 87.5% at 50 years. Six percent of carriers were homozygous and 18% had an additional variant. Family origin was concentrated in Galicia, Extremadura, and northern Portugal, suggesting a founder effect. CONCLUSIONS TPM1 p.Arg21Leu is a pathogenic HCM variant associated with late-onset/incomplete penetrance and a generally favorable prognosis.
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Biswas A, Raza A, Das S, Kapoor M, Jayarajan R, Verma A, Shamsudheen KV, Murry B, Seth S, Bhargava B, Scaria V, Sivasubbu S, Rao VR. Loss of function mutation in the P2X7, a ligand-gated ion channel gene associated with hypertrophic cardiomyopathy. Purinergic Signal 2019; 15:205-210. [PMID: 31152337 DOI: 10.1007/s11302-019-09660-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 05/16/2019] [Indexed: 12/21/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is an inherited heart failure condition, mostly found to have genetic abnormalities, and is a leading cause of sudden death in young adults. Whole exome sequencing should be given consideration as a molecular diagnostic tool to identify disease-causing mutation/s. In this study, a HCM family with multiple affected members having history of sudden death were subjected to exome sequencing along with unaffected members. Quality passed variants obtained were filtered for rarity (MAF > 0.5%), evolutionary conservation, pathogenic prediction, and segregation in affected members after removing shared variants present in unaffected members. Only one non-synonymous mutation (p. Glu186Lys or E186K) in exon 6 of P2X7 gene segregated in HCM-affected individuals which was absent in unaffected family members and 100 clinically evaluated controls. The site of the mutation is highly conserved and led to complete loss of function which is in close vicinity to ATP-binding site-forming residues, affecting ATP binding, channel gating, or both. Mutations in candidate genes which were not segregated define clinical heterogeneity within affected members. P2X7 gene is highly expressed in the heart and shows direct interaction with major candidate genes for HCM. Our results reveal a significant putative HCM causative gene, P2X7, for the first time and show that germ-line mutations in P2X7 may cause a defective phenotype, suggesting purinergic receptor involvement in heart failure mediated through arrhythmias which need further investigations to be targeted for therapeutic interventions.
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Affiliation(s)
- Amitabh Biswas
- Department of Anthropology, University of Delhi, New Delhi, India
- College of Natural Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Ali Raza
- College of Natural Sciences, Arba Minch University, Arba Minch, Ethiopia
| | - Soumi Das
- Department of Anthropology, University of Delhi, New Delhi, India
| | - Mitali Kapoor
- Department of Anthropology, University of Delhi, New Delhi, India
| | - Rijith Jayarajan
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Ankit Verma
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | | | - Benrithung Murry
- Department of Anthropology, University of Delhi, New Delhi, India
| | - Sandeep Seth
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Balram Bhargava
- Department of Cardiology, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Vinod Scaria
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Sridhar Sivasubbu
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Vadlamudi Raghavendra Rao
- Department of Anthropology, University of Delhi, New Delhi, India.
- Department of Genetics, Osmania University, Hyderabad, India.
- Genome Foundation, Hyderabad, 500007, India.
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7
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Matyushenko AM, Shchepkin DV, Kopylova GV, Popruga KE, Artemova NV, Pivovarova AV, Bershitsky SY, Levitsky DI. Structural and Functional Effects of Cardiomyopathy-Causing Mutations in the Troponin T-Binding Region of Cardiac Tropomyosin. Biochemistry 2016; 56:250-259. [PMID: 27983818 DOI: 10.1021/acs.biochem.6b00994] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is a severe heart disease caused by missense mutations in genes encoding sarcomeric proteins of cardiac muscle. Many of these mutations are identified in the gene encoding the cardiac isoform of tropomyosin (Tpm), an α-helical coiled-coil actin-binding protein that plays a key role in Ca2+-regulated contraction of cardiac muscle. We employed various methods to characterize structural and functional features of recombinant human Tpm species carrying HCM mutations that lie either within the troponin T-binding region in the C-terminal part of Tpm (E180G, E180V, and L185R) or near this region (I172T). The results of our structural studies show that all these mutations affect, although differently, the thermal stability of the C-terminal part of the Tpm molecule: mutations E180G and I172T destabilize this part of the molecule, whereas mutation E180V strongly stabilizes it. Moreover, various HCM-causing mutations have different and even opposite effects on the stability of the Tpm-actin complexes. Studies of reconstituted thin filaments in the in vitro motility assay have shown that those HCM-associated mutations that lie within the troponin T-binding region of Tpm similarly increase the Ca2+ sensitivity of the sliding velocity of the filaments and impair their relaxation properties, causing a marked increase in the sliding velocity in the absence of Ca2+, while mutation I172T decreases the Ca2+ sensitivity and has no influence on the sliding velocity under relaxing conditions. Finally, our data demonstrate that various HCM mutations can differently affect the structural and functional properties of Tpm and cause HCM by different molecular mechanisms.
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Affiliation(s)
- Alexander M Matyushenko
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences , Leninsky Prospect 33, Moscow 119071, Russian Federation.,Department of Biochemistry, School of Biology, Moscow State University , Lenin Hills 1, bld 12, Moscow 119234, Russian Federation
| | - Daniil V Shchepkin
- Institute of Immunology and Physiology, Russian Academy of Sciences , Pervomayskaya Street 106, Yekaterinburg 620049, Russian Federation
| | - Galina V Kopylova
- Institute of Immunology and Physiology, Russian Academy of Sciences , Pervomayskaya Street 106, Yekaterinburg 620049, Russian Federation
| | - Katerina E Popruga
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences , Leninsky Prospect 33, Moscow 119071, Russian Federation.,Department of Biochemistry, School of Biology, Moscow State University , Lenin Hills 1, bld 12, Moscow 119234, Russian Federation
| | - Natalya V Artemova
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences , Leninsky Prospect 33, Moscow 119071, Russian Federation
| | - Anastasia V Pivovarova
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences , Leninsky Prospect 33, Moscow 119071, Russian Federation
| | - Sergey Y Bershitsky
- Institute of Immunology and Physiology, Russian Academy of Sciences , Pervomayskaya Street 106, Yekaterinburg 620049, Russian Federation
| | - Dmitrii I Levitsky
- A. N. Bach Institute of Biochemistry, Research Center of Biotechnology, Russian Academy of Sciences , Leninsky Prospect 33, Moscow 119071, Russian Federation.,A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University , Lenin Hills 1, bld 40, Moscow 119234, Russian Federation
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Zheng W, Hitchcock-DeGregori SE, Barua B. Investigating the effects of tropomyosin mutations on its flexibility and interactions with filamentous actin using molecular dynamics simulation. J Muscle Res Cell Motil 2016; 37:131-147. [DOI: 10.1007/s10974-016-9447-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 06/24/2016] [Indexed: 12/15/2022]
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9
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Gupte TM, Haque F, Gangadharan B, Sunitha MS, Mukherjee S, Anandhan S, Rani DS, Mukundan N, Jambekar A, Thangaraj K, Sowdhamini R, Sommese RF, Nag S, Spudich JA, Mercer JA. Mechanistic heterogeneity in contractile properties of α-tropomyosin (TPM1) mutants associated with inherited cardiomyopathies. J Biol Chem 2014; 290:7003-15. [PMID: 25548289 DOI: 10.1074/jbc.m114.596676] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The most frequent known causes of primary cardiomyopathies are mutations in the genes encoding sarcomeric proteins. Among those are 30 single-residue mutations in TPM1, the gene encoding α-tropomyosin. We examined seven mutant tropomyosins, E62Q, D84N, I172T, L185R, S215L, D230N, and M281T, that were chosen based on their clinical severity and locations along the molecule. The goal of our study was to determine how the biochemical characteristics of each of these mutant proteins are altered, which in turn could provide a structural rationale for treatment of the cardiomyopathies they produce. Measurements of Ca(2+) sensitivity of human β-cardiac myosin ATPase activity are consistent with the hypothesis that hypertrophic cardiomyopathies are hypersensitive to Ca(2+) activation, and dilated cardiomyopathies are hyposensitive. We also report correlations between ATPase activity at maximum Ca(2+) concentrations and conformational changes in TnC measured using a fluorescent probe, which provide evidence that different substitutions perturb the structure of the regulatory complex in different ways. Moreover, we observed changes in protein stability and protein-protein interactions in these mutants. Our results suggest multiple mechanistic pathways to hypertrophic and dilated cardiomyopathies. Finally, we examined a computationally designed mutant, E181K, that is hypersensitive, confirming predictions derived from in silico structural analysis.
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Affiliation(s)
- Tejas M Gupte
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
| | - Farah Haque
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India, the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Binnu Gangadharan
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India, the Manipal University, Madhav Nagar, Manipal 576104, India
| | - Margaret S Sunitha
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India, the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Souhrid Mukherjee
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
| | - Swetha Anandhan
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
| | - Deepa Selvi Rani
- the Council for Scientific and Industrial Research-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Namita Mukundan
- the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Amruta Jambekar
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
| | - Kumarasamy Thangaraj
- the Council for Scientific and Industrial Research-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Ramanathan Sowdhamini
- the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore 560065, India
| | - Ruth F Sommese
- the Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, and
| | - Suman Nag
- the Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, and
| | - James A Spudich
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India, the Department of Biochemistry, Stanford University School of Medicine, Stanford, California 94305, and
| | - John A Mercer
- From the Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India, the McLaughlin Research Institute, Great Falls, Montana 59405
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10
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Chang AN, Greenfield NJ, Singh A, Potter JD, Pinto JR. Structural and protein interaction effects of hypertrophic and dilated cardiomyopathic mutations in alpha-tropomyosin. Front Physiol 2014; 5:460. [PMID: 25520664 PMCID: PMC4251307 DOI: 10.3389/fphys.2014.00460] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2014] [Accepted: 11/10/2014] [Indexed: 12/16/2022] Open
Abstract
The potential alterations to structure and associations with thin filament proteins caused by the dilated cardiomyopathy (DCM) associated tropomyosin (Tm) mutants E40K and E54K, and the hypertrophic cardiomyopathy (HCM) associated Tm mutants E62Q and L185R, were investigated. In order to ascertain what the cause of the known functional effects may be, structural and protein-protein interaction studies were conducted utilizing actomyosin ATPase activity measurements and spectroscopy. In actomyosin ATPase measurements, both HCM mutants and the DCM mutant E54K caused increases in Ca2+-induced maximal ATPase activities, while E40K caused a decrease. Investigation of Tm's ability to inhibit actomyosin ATPase in the absence of troponin showed that HCM-associated mutant Tms did not inhibit as well as wildtype, whereas the DCM associated mutant E40K inhibited better. E54K did not inhibit the actomyosin ATPase activity at any concentration of Tm tested. Thermal denaturation studies by circular dichroism and molecular modeling of the mutations in Tm showed that in general, the DCM mutants caused localized destabilization of the Tm dimers, while the HCM mutants resulted in increased stability. These findings demonstrate that the structural alterations in Tm observed here may affect the regulatory function of Tm on actin, thereby directly altering the ATPase rates of myosin.
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Affiliation(s)
- Audrey N Chang
- Department of Molecular and Cellular Pharmacology, Leonard Miller School of Medicine, University of Miami Miami, FL, USA
| | - Norma J Greenfield
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University New Jersey, NJ, USA
| | - Abhishek Singh
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University New Jersey, NJ, USA ; Department of Cardiology, UCSF Medical Center, University of California, San Francisco San Francisco, CA, USA
| | - James D Potter
- Department of Molecular and Cellular Pharmacology, Leonard Miller School of Medicine, University of Miami Miami, FL, USA
| | - Jose R Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine Tallahassee, FL, USA
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11
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Kapplinger JD, Landstrom AP, Bos JM, Salisbury BA, Callis TE, Ackerman MJ. Distinguishing hypertrophic cardiomyopathy-associated mutations from background genetic noise. J Cardiovasc Transl Res 2014; 7:347-61. [PMID: 24510615 DOI: 10.1007/s12265-014-9542-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/13/2014] [Indexed: 01/24/2023]
Abstract
Despite the significant progress that has been made in identifying disease-associated mutations, the utility of the hypertrophic cardiomyopathy (HCM) genetic test is limited by a lack of understanding of the background genetic variation inherent to these sarcomeric genes in seemingly healthy subjects. This study represents the first comprehensive analysis of genetic variation in 427 ostensibly healthy individuals for the HCM genetic test using the "gold standard" Sanger sequencing method validating the background rate identified in the publically available exomes. While mutations are clearly overrepresented in disease, a background rate as high as ∼5 % among healthy individuals prevents diagnostic certainty. To this end, we have identified a number of estimated predictive value-based associations including gene-specific, topology, and conservation methods generating an algorithm aiding in the probabilistic interpretation of an HCM genetic test.
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Affiliation(s)
- Jamie D Kapplinger
- Department of Molecular Pharmacology & Experimental Therapeutics, Mayo Clinic, Rochester, MN, USA
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12
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13
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Redwood C, Robinson P. Alpha-tropomyosin mutations in inherited cardiomyopathies. J Muscle Res Cell Motil 2013; 34:285-94. [DOI: 10.1007/s10974-013-9358-5] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 08/23/2013] [Indexed: 10/26/2022]
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14
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Meurs KM, Kuan M. Differential methylation of CpG sites in two isoforms of myosin binding protein C, an important hypertrophic cardiomyopathy gene. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2011; 52:161-164. [PMID: 20740642 DOI: 10.1002/em.20596] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Accepted: 04/19/2010] [Indexed: 05/29/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is a common form of cardiac disease. Over 400 causative mutations have been identified in 20 sarcomere and myofilament related genes. The high density of mutations found in genes associated with HCM may suggest that mechanisms promoting increased mutability play a role in disease prevalence. The objective of this study was to evaluate the CpG methylation level of the exonic regions of the cardiac myosin binding protein C gene (MYBPC3), a common causal gene for HCM. To determine if the methylation level is gene specific and possibly involved with gene mutability, we also evaluated the methylation of the CpGs within the exonic regions of the skeletal muscle isoform of the myosin binding protein C gene (MYBPC2); there are no known mutations that lead to the development of familial human disease within this gene. We determined that although the mean number of CG sites was identical within the coding region of each gene, the mean methylation level of CpGs was significantly higher in MYBPC3 than MYBPC2 (P < 0.0001). The results of this study suggest that there are unique aspects of this cardiac gene or its epigenetic environment which may result in increased genetic mutability. Evaluation of the methylation levels of additional causal cardiomyopathic genes is warranted.
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Affiliation(s)
- Kathryn M Meurs
- Department of Clinical Sciences, Washington State University, Pullman, Washington 99164, USA.
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15
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Clinical spectrum in a family with tropomyosin-mediated hypertrophic cardiomyopathy and sudden death in childhood. Pediatr Cardiol 2011; 32:215-20. [PMID: 21085943 DOI: 10.1007/s00246-010-9843-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Accepted: 11/01/2010] [Indexed: 10/18/2022]
Abstract
This report demonstrates variable clinical courses in several members of a family with tropomyosin-mediated hypertrophic cardiomyopathy (HCM) (L185R mutation). The index case was an 8-year-old girl who died from sudden cardiac death and was diagnosed with HCM on autopsy. Her father had minimal hypertrophy but had an implantable cardioverter defibrillator placed prophylactically with no appropriate shocks. Two brothers progressed from normal phenotype to HCM on follow-up, the younger with significant hypertrophy and the older with mild hypertrophy. They both had malignant arrhythmia courses with VF, which was terminated by ICD shock. In conclusion, family members with same genotype can have significantly variable phenotypes.
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16
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17
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Rai TS, Dhandapany PS, Ahluwalia TS, Bhardwaj M, Bahl A, Talwar KK, Nair K, Rathinavel A, Khullar M. ACE I/D polymorphism in Indian patients with hypertrophic cardiomyopathy and dilated cardiomyopathy. Mol Cell Biochem 2007; 311:67-72. [PMID: 18165925 DOI: 10.1007/s11010-007-9695-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 12/17/2007] [Indexed: 10/22/2022]
Abstract
AIM The study was carried to determine the association of angiotensin converting enzyme (ACE) insertion/deletion (I/D) polymorphism with the risk of hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and restrictive cardiomyopathy (RCM). METHODS AND RESULTS A total of 174 patients diagnosed with cardiomyopathy (118 with HCM, 51 with DCM, and 5 with RCM) and 164 ethnically, age- and gender-matched controls were included in the study. ACE I/D genotyping was performed by PCR. In total, 25.86% of the patients were in New York Heart Association (NYHA) class III and IV at presentation. A total of 67.24% patients had dyspnea, 56.89% had angina pectoris, and 25.28% of the patients had at least one event of syncope. Frequency of occurrence of the disease was more in male patients compared to female patients (P < 0.05). After adjustment for age, sex, body mass index (BMI), and smoking habit, the prevalence of ACE DD genotype, and ACE 'D' allele was significantly higher in patients as compared to controls and was associated with increased risk (DD: OR 2.11, 95% CI 1.27-3.52, P < 0.05; 'D': OR 1.91, 95% CI 1.08-3.35, P < 0.05). The mean septal thickness was higher for DD and ID genotypes (20.40 +/- 3.73 mm and 21.82 +/- 5.35 mm, respectively) when compared with II genotype (18.63 +/- 6.69 mm) in HCM patients, however, the differences were not significant statistically (P > 0.05). The DCM patients with ID genotype showed significantly decreased left ventricular ejection fraction (LVEF) at enrolment (26.50 +/- 8.04%) (P = 0.04). CONCLUSION Our results suggest that D allele of ACE I/D polymorphism significantly influences the HCM and DCM phenotypes.
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Affiliation(s)
- Taranjit Singh Rai
- Department of Experimental Medicine and Biotechnology, Post Graduate Institute of Medical Education and Research, Chandigarh 160012, India
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18
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Frazier A, Murphy AM. Repairing the myofilaments to heal the heart. Am J Physiol Heart Circ Physiol 2007; 293:H907-8. [PMID: 17416606 DOI: 10.1152/ajpheart.00272.2007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
MESH Headings
- Actin Cytoskeleton/drug effects
- Actin Cytoskeleton/metabolism
- Animals
- Calcium/metabolism
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/metabolism
- Cardiomyopathy, Hypertrophic, Familial/pathology
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Cardiomyopathy, Hypertrophic, Familial/therapy
- Disease Models, Animal
- Gene Transfer Techniques
- Genetic Therapy/methods
- Genotype
- Mice
- Mice, Transgenic
- Mutation
- Myocardial Contraction/drug effects
- Myocardium/metabolism
- Myocardium/pathology
- Phenotype
- RNA, Messenger/metabolism
- Recombinant Fusion Proteins/metabolism
- Severity of Illness Index
- Tropomyosin/genetics
- Tropomyosin/metabolism
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Affiliation(s)
- Aisha Frazier
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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19
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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: 150] [Impact Index Per Article: 8.3] [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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20
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Yamazaki T, Suzuki JI, Shimamoto R, Tsuji T, Ohmoto Y, Toyo-oka T, Omata M, Ohtomo K, Nagai R. Focalized Contractile Impairment at Hypertrophied Myocardium Proven in Consideration of Wall Stress in Patients With Hypertrophic Cardiomyopathy. Int Heart J 2006; 47:247-58. [PMID: 16607052 DOI: 10.1536/ihj.47.247] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In hypertrophic cardiomyopathy (HCM) a hyperkinetic state is sometimes observed in spite of impaired systolic function in the hypertrophied myocardium. The aim of the present study was to determine the mechanism of this paradox. Seventeen patients with HCM and 10 normal subjects underwent cine magnetic resonance (MR) imaging to measure percent systolic wall thickening and percent fractional shortening. The ratio of systolic radial wall stress of the LV at the hypertrophied myocardium over that at the nonhypertrophied myocardium was evaluated to describe the focal advantageous condition for wall thickening. The ratio was 0.66 +/- 0.36 at the start of contraction and 0.78 +/- 0.31 at early-systole, indicating consistently smaller radial wall stress at the hypertrophied myocardium. Although the condition for contraction was favorable (a ratio less than 1.00), percent systolic wall thickening at the hypertrophied myocardium (23.0 +/- 11.8%) was smaller than that at the nonhypertrophied myocardium (70.5 +/- 32.3%). Smaller end-diastolic dimension (HCM group; 45.2 +/- 4.2 mm, reference group; 48.9 +/- 4.1 mm, P = 0.04) with a statistically identical value of systolic decrease in intraventricular dimension (HCM group; 19.7 +/- 3.9 mm, reference group; 18.9 +/- 3.2 mm, P = 0.60) yielded high percent fractional shortening in patients with HCM (43.5 +/- 7.6%). Although contractile impairment was proven at the hypertrophied region with low radial wall stress in the HCM group, the smaller end-diastolic dimension in this group resulted in high percent fractional shortening.
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Affiliation(s)
- Tadashi Yamazaki
- Department of Internal Medicine, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Japan
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21
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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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22
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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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23
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Van Driest SL, Gakh O, Ommen SR, Isaya G, Ackerman MJ. Molecular and functional characterization of a human frataxin mutation found in hypertrophic cardiomyopathy. Mol Genet Metab 2005; 85:280-5. [PMID: 15936968 DOI: 10.1016/j.ymgme.2005.04.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2005] [Accepted: 04/26/2005] [Indexed: 11/30/2022]
Abstract
Hypertrophic cardiomyopathy is associated with marked genetic and phenotypic heterogeneity. Pathogenic mutations in the 10 hypertrophic cardiomyopathy-associated sarcomeric genes cause autosomal dominant disease as a rule, although recessive disease has been reported. Cardiac hypertrophy is also a hallmark of Friedreich ataxia, an autosomal recessive disease caused by deficiency of the mitochondrial protein frataxin. We hypothesized that heterozygous mutations in frataxin may mimic or modify hypertrophic cardiomyopathy. Using DHPLC and DNA sequencing, we identified the novel R40C-frataxin mutation in a patient who also harbored a previously reported R810H-myosin binding protein C mutation. The R810H mutation is reported to cause hypertrophic cardiomyopathy only in the setting of homozygosity or compound heterozygosity with another sarcomeric mutation. Site-directed mutagenesis and in vitro and in vivo analysis enabled functional characterization of the mutant frataxin protein. R40C-frataxin protein is not cleaved to the mature form in vitro and shows delayed kinetics of cleavage by isolated mouse mitochondria. Yeast cells expressing R40C-frataxin demonstrated increased sensitivity to oxidative stress and abnormal accumulation of precursor frataxin protein. These data indicate that frataxin deficiency may have contributed to this patient's particular phenotype. Furthermore, these findings suggest that mutations altering myocyte energetics may act in synergy with sarcomeric mutations to cause hypertrophic cardiomyopathy.
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Affiliation(s)
- Sara L Van Driest
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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24
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Abstract
OBJECTIVE To determine the clinical parameters of hypertrophic cardiomyopathy (HCM) that correlated significantly with the presence of an identifiable sarcomeric mutation. PATIENTS AND METHODS Previous comprehensive mutational analyses of all protein-coding exons of 8 sarcomeric genes revealed pathogenic mutations in 147 (38%) of 389 unrelated patients seen at the HCM outpatient clinic at the Mayo Clinic in Rochester, Minn, between April 1997 and December 2001. Clinical data, extracted from patient records and blinded to patient genotype, were maintained in a custom database. RESULTS In 389 unrelated patients, younger age at diagnosis, family history of HCM, and Increasing left ventricular wall thickness were all associated with Increased likelihood of identifying an HCM-associated sarcomeric mutation. In contrast, family history of sudden cardiac death, myectomy status, and anatomical subtype did not correlate significantly with genotype-positive status. With use of a simple scoring system based on age at diagnosis, left ventricular wall thickness, and family history of HCM, the likelihood of a sarcomeric mutation could be estimated. CONCLUSION Clinical predictors of positive genotype, such as the presence of an implantable cardioverter-defibrillator, age at diagnosis, degree of left ventricular wall hypertrophy, and family history of HCM, may aid in patient selection for genetic testing and increase the yield of cardiac sarcomere gene screening.
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Affiliation(s)
- Sara L Van Driest
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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25
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Hilario E, da Silva SLF, Ramos CHI, Bertolini MC. Effects of cardiomyopathic mutations on the biochemical and biophysical properties of the human alpha-tropomyosin. ACTA ACUST UNITED AC 2005; 271:4132-40. [PMID: 15479242 DOI: 10.1111/j.1432-1033.2004.04351.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mutations in the protein alpha-tropomyosin (Tm) can cause a disease known as familial hypertrophic cardiomyopathy. In order to understand how such mutations lead to protein dysfunction, three point mutations were introduced into cDNA encoding the human skeletal tropomyosin, and the recombinant Tms were produced at high levels in the yeast Pichia pastoris. Two mutations (A63V and K70T) were located in the N-terminal region of Tm and one (E180G) was located close to the calcium-dependent troponin T binding domain. The functional and structural properties of the mutant Tms were compared to those of the wild type protein. None of the mutations altered the head-to-tail polymerization, although slightly higher actin binding was observed in the mutant Tm K70T, as demonstrated in a cosedimentation assay. The mutations also did not change the cooperativity of the thin filament activation by increasing the concentrations of Ca2+. However, in the absence of troponin, all mutant Tms were less effective than the wild type in regulating the actomyosin subfragment 1 Mg2+ ATPase activity. Circular dichroism spectroscopy revealed no differences in the secondary structure of the Tms. However, the thermally induced unfolding, as monitored by circular dichroism or differential scanning calorimetry, demonstrated that the mutants were less stable than the wild type. These results indicate that the main effect of the mutations is related to the overall stability of Tm as a whole, and that the mutations have only minor effects on the cooperative interactions among proteins that constitute the thin filament.
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Affiliation(s)
- Eduardo Hilario
- Instituto de Química, UNESP, Departamento de Bioquímica e Tecnologia Química, Araraquara, São Paulo, Brazil
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26
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Wernicke D, Thiel C, Duja-Isac CM, Essin KV, Spindler M, Nunez DJR, Plehm R, Wessel N, Hammes A, Edwards RJ, Lippoldt A, Zacharias U, Strömer H, Neubauer S, Davies MJ, Morano I, Thierfelder L. α-Tropomyosin mutations Asp175Asn and Glu180Gly affect cardiac function in transgenic rats in different ways. Am J Physiol Regul Integr Comp Physiol 2004; 287:R685-95. [PMID: 15031138 DOI: 10.1152/ajpregu.00620.2003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To study the mechanisms by which missense mutations in α-tropomyosin cause familial hypertrophic cardiomyopathy, we generated transgenic rats overexpressing α-tropomyosin with one of two disease-causing mutations, Asp175Asn or Glu180Gly, and analyzed phenotypic changes at molecular, morphological, and physiological levels. The transgenic proteins were stably integrated into the sarcomere, as shown by immunohistochemistry using a human-specific anti-α-tropomyosin antibody, ARG1. In transgenic rats with either α-tropomyosin mutation, molecular markers of cardiac hypertrophy were induced. Ca2+sensitivity of cardiac skinned-fiber preparations from animals with mutation Asp175Asn, but not Glu180Gly, was decreased. Furthermore, elevated frequency and amplitude of spontaneous Ca2+waves were detected only in cardiomyocytes from animals with mutation Asp175Asn, suggesting an increase in intracellular Ca2+concentration compensating for the reduced Ca2+sensitivity of isometric force generation. Accordingly, in Langendorff-perfused heart preparations, myocardial contraction and relaxation were accelerated in animals with mutation Asp175Asn. The results allow us to propose a hypothesis of the pathogenetic changes caused by α-tropomyosin mutation Asp175Asn in familial hypertrophic cardiomyopathy on the basis of changes in Ca2+handling as a sensitive mechanism to compensate for alterations in sarcomeric structure.
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MESH Headings
- Animals
- Animals, Genetically Modified
- Asparagine
- Aspartic Acid
- Biomarkers/analysis
- Calcium/metabolism
- Calcium/pharmacology
- Cardiomyopathy, Hypertrophic, Familial/genetics
- Cardiomyopathy, Hypertrophic, Familial/metabolism
- Cardiomyopathy, Hypertrophic, Familial/physiopathology
- Gene Expression
- Glutamic Acid
- Glycine
- Heart/physiopathology
- Heart Ventricles
- Humans
- Immunohistochemistry
- In Vitro Techniques
- Muscle Fibers, Skeletal/drug effects
- Mutation, Missense
- Myocardial Contraction
- Myocytes, Cardiac/metabolism
- Rats
- Sarcomeres/metabolism
- Transgenes
- Tropomyosin/genetics
- Tropomyosin/metabolism
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Affiliation(s)
- Dirk Wernicke
- Max-Delbrück Center for Molecular Medicine, Robert-Roessle-Str. 10, Berlin 13092, Germany.
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27
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Coutu P, Bennett CN, Favre EG, Day SM, Metzger JM. Parvalbumin Corrects Slowed Relaxation in Adult Cardiac Myocytes Expressing Hypertrophic Cardiomyopathy-Linked α-Tropomyosin Mutations. Circ Res 2004; 94:1235-41. [PMID: 15059934 DOI: 10.1161/01.res.0000126923.46786.fd] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypertrophic cardiomyopathy mutations A63V and E180G in α-tropomyosin (α-Tm) have been shown to cause slow cardiac muscle relaxation. In this study, we used two complementary genetic strategies, gene transfer in isolated rat myocytes and transgenesis in mice, to ascertain whether parvalbumin (Parv), a myoplasmic calcium buffer, could correct the diastolic dysfunction caused by these mutations. Sarcomere shortening measurements in rat cardiac myocytes expressing the α-Tm A63V mutant revealed a slower time to 50% relengthening (T50R: 44.2±1.4 ms in A63V, 36.8±1.0 ms in controls; n=96 to 108;
P
<0.001) when compared with controls. Dual gene transfer of α-Tm A63V and Parv caused a marked decrease in T50R (29.8±1.0 ms). However, this increase in relaxation rate was accompanied with a decrease in shortening amplitude (114.6±4.4 nm in A63+Parv, 137.8±5.3 nm in controls). Using an asynchronous gene transfer strategy, Parv expression was reduced (from ≈0.12 to ≈0.016 mmol/L), slow relaxation redressed, and shortening amplitude maintained (T50R=33.9±1.6 ms, sarcomere shortening amplitude=132.2±7.0 nm in A63V+PVdelayed; n=56). Transgenic mice expressing the E180G α-Tm mutation and mice expressing Parv in the heart were crossed. In isolated adult myocytes, the α-Tm mutation alone (E180G
+
/PV
−
) had slower sarcomere relengthening kinetics than the controls (T90R: 199±7 ms in E180G
+
/PV
−
, 130±4 ms in E180G
−
/PV
−
; n=71 to 72), but when coexpressed with Parv, cellular relaxation was faster (T90R: 36±4 ms in E180G
+
/PV
+
). Collectively, these findings show that slow relaxation caused by α-Tm mutants can be corrected by modifying calcium handling with Parv.
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Affiliation(s)
- Pierre Coutu
- Department of Biomedical Engineering , University of Michigan, Ann Arbor, Mich 48109-0622, USA
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Van Driest SL, Ellsworth EG, Ommen SR, Tajik AJ, Gersh BJ, Ackerman MJ. Prevalence and spectrum of thin filament mutations in an outpatient referral population with hypertrophic cardiomyopathy. Circulation 2003; 108:445-51. [PMID: 12860912 DOI: 10.1161/01.cir.0000080896.52003.df] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Thin filament mutations are reported to cause approximately 20% of cases of hypertrophic cardiomyopathy (HCM), and they have been associated with specific phenotypes. However, the frequency of these mutations and their associated phenotype(s) from a large tertiary referral center population are unknown. METHODS AND RESULTS DNA was obtained from 389 unrelated patients with HCM. A mutational analysis of all protein coding exons of cardiac troponin T, cardiac troponin I, alpha-tropomyosin, and cardiac actin was performed using polymerase chain reaction, denaturing high-performance liquid chromatography, and DNA sequencing. The clinical data were extracted from patient records and maintained independent of the patient genotype. Overall, only 18 patients (4.6%) harbored isolated thin filament mutations: 8 had troponin T mutations, 6 had troponin I mutations, 3 had alpha-tropomyosin mutations, and 1 had an actin mutation. Of the 12 unique missense mutations identified, 9 (75%) were novel mutations. As a group, patients with thin filament mutations were not significantly different from the rest of the cohort in age at diagnosis, left ventricular wall thickness, left ventricular outflow tract obstruction, or family history of HCM or sudden cardiac death. CONCLUSIONS Mutations in genes encoding thin filament proteins are less prevalent in HCM than previously estimated. Patients with mutations in troponin T, troponin I, alpha-tropomyosin, and actin do not invariably present with any distinct clinical feature, thus limiting the utility of gene status for risk stratification or of clinical phenotype in guiding individual genetic screening at this time.
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Affiliation(s)
- Sara L Van Driest
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minn 55905, USA
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Earing MG, Ackerman MJ, O'Leary PW. Diastolic ventricular dysfunction as a marker for hypertrophic cardiomyopathy in a family with a novel alpha-tropomyosin mutation. J Am Soc Echocardiogr 2003; 16:698-702. [PMID: 12778034 DOI: 10.1016/s0894-7317(03)00285-2] [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: 11/25/2022]
Abstract
BACKGROUND Early identification of familial cases of hypertrophic cardiomyopathy (HCM) depends on screening echocardiography, but hypertrophy may not be the most sensitive marker for the disease. We report the echocardiographic findings of a family with HCM and a newly reported mutation in the gene (TPM1) encoding alpha-tropomyosin.Methods and results An 8-year-old girl had sudden cardiac death, and was found to have HCM and a novel L185R-TPM1 mutation on postmortem examination. Screening echocardiograms and DNA analyses were performed on her family. Of the 5 remaining family members, 3 were genetically affected. Those without the TPM1 mutation had normal echocardiographic results. The only echocardiographic finding that identified all 3 of the gene-positive family members was an abnormal left ventricular diastolic filling pattern. CONCLUSION Abnormal left ventricular diastolic filling patterns, indicating diastolic dysfunction, may provide an early marker for the diagnosis of familial HCM in children, even in the absence of left ventricular hypertrophy.
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Affiliation(s)
- Michael G Earing
- Departments of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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Van Driest SL, Ackerman MJ, Ommen SR, Shakur R, Will ML, Nishimura RA, Tajik AJ, Gersh BJ. Prevalence and severity of "benign" mutations in the beta-myosin heavy chain, cardiac troponin T, and alpha-tropomyosin genes in hypertrophic cardiomyopathy. Circulation 2002; 106:3085-90. [PMID: 12473556 DOI: 10.1161/01.cir.0000042675.59901.14] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Genotype-phenotype correlative studies have implicated 8 particular mutations that cause hypertrophic cardiomyopathy (HCM) as "benign defects," associated with near-normal survival: N232S, G256E, F513C, V606M, R719Q, and L908V of beta-myosin heavy chain (MYH7); S179F of troponin T (TNNT2); and D175N of alpha-tropomyosin (TPM1). Routine genetic screening of HCM patients for specific mutations is anticipated to provide important diagnostic and prognostic information. The frequency and associated phenotype of these mutations in a large, unselected cohort of HCM is unknown. METHODS AND RESULTS A total of 293 unrelated HCM patients were genotyped for the presence of a benign mutation. DNA was obtained after informed consent; specific MHY7, TNNT2, and TPM1 fragments were amplified by polymerase chain reaction; and the mutations were detected by denaturing high-performance liquid chromatography and automated DNA sequencing. Only 5 (1.7%) of the 293 patients possessed a benign mutation. Moreover, all 5 subjects with an ascribed benign mutation had already manifested clinically severe expression of HCM, with all 5 requiring surgical myectomy, 3 of the 5 having a family history of sudden cardiac death, and 1 adolescent requiring an orthotopic heart transplant. CONCLUSIONS These findings demonstrate the rarity of specific mutations in HCM and challenge the notion of mutation-specific clinical outcomes. Fewer than 2% of the subjects harbored a benign mutation, and those patients with a benign mutation experienced a very serious clinical course.
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Affiliation(s)
- Sara L Van Driest
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minn 55905, USA
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