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Polavarapu K, O'Neil D, Thompson R, Spendiff S, Nandeesh B, Vengalil S, Huddar A, Baskar D, Arunachal G, Kotambail A, Bhatia S, Tumulu SK, Matalonga L, Töpf A, Laurie S, Zeldin J, Nashi S, Unnikrishnan G, Nalini A, Lochmüller H. Partial loss of desmin expression due to a leaky splice site variant in the human DES gene is associated with neuromuscular transmission defects. Neuromuscul Disord 2024; 39:10-18. [PMID: 38669730 DOI: 10.1016/j.nmd.2024.03.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 02/15/2024] [Accepted: 03/20/2024] [Indexed: 04/28/2024]
Abstract
Recessive desminopathies are rare and often present as severe early-onset myopathy. Here we report a milder phenotype in three unrelated patients from southern India (2 M, 1F) aged 16, 21, and 22 years, who presented with childhood-onset, gradually progressive, fatigable limb-girdle weakness, ptosis, speech and swallowing difficulties, without cardiac involvement. Serum creatine kinase was elevated, and repetitive nerve stimulation showed decrement in all. Clinical improvement was noted with pyridostigmine and salbutamol in two patients. All three patients had a homozygous substitution in intron 5: DES(NM_001927.4):c.1023+5G>A, predicted to cause a donor splice site defect. Muscle biopsy with ultrastructural analysis suggested myopathy with myofibrillar disarray, and immunohistochemistry showed partial loss of desmin with some residual staining, while western blot analysis showed reduced desmin. RT-PCR of patient muscle RNA revealed two transcripts: a reduced normal desmin transcript and a larger abnormal transcript suggesting leaky splicing at the intron 5 donor site. Sequencing of the PCR products confirmed the inclusion of intron 5 in the longer transcript, predicted to cause a premature stop codon. Thus, we provide evidence for a leaky splice site causing partial loss of desmin associated with a unique phenotypic presentation of a milder form of desmin-related recessive myopathy overlapping with congenital myasthenic syndrome.
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Affiliation(s)
- Kiran Polavarapu
- Childrens Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Daniel O'Neil
- Childrens Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Rachel Thompson
- Childrens Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Sally Spendiff
- Childrens Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Bevinahalli Nandeesh
- Department of Neuropathology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Seena Vengalil
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Akshata Huddar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Dipti Baskar
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Gautham Arunachal
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | | | - Saloni Bhatia
- Department of Human Genetics, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Seetam Kumar Tumulu
- Department of Neuroradiology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | - Leslie Matalonga
- Centro Nacional de Análisis Genómico, Baldiri Reixac 4, Barcelona 08028, Spain
| | - Ana Töpf
- John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom
| | - Steven Laurie
- Centro Nacional de Análisis Genómico, Baldiri Reixac 4, Barcelona 08028, Spain
| | - Joshua Zeldin
- Childrens Hospital of Eastern Ontario Research Institute, Ottawa, Canada
| | - Saraswati Nashi
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India
| | | | - Atchayaram Nalini
- Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, India.
| | - Hanns Lochmüller
- Childrens Hospital of Eastern Ontario Research Institute, Ottawa, Canada; Centro Nacional de Análisis Genómico, Baldiri Reixac 4, Barcelona 08028, Spain; Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada; Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada; Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.
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2
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Geryk M, Charpentier F. Pathophysiological mechanisms of cardiomyopathies induced by desmin gene variants located in the C-Terminus of segment 2B. J Cell Physiol 2024; 239:e31254. [PMID: 38501553 DOI: 10.1002/jcp.31254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 02/28/2024] [Accepted: 03/05/2024] [Indexed: 03/20/2024]
Abstract
Desmin, the most abundant intermediate filament in cardiomyocytes, plays a key role in maintaining cardiomyocyte structure by interconnecting intracellular organelles, and facilitating cardiomyocyte interactions with the extracellular matrix and neighboring cardiomyocytes. As a consequence, mutations in the desmin gene (DES) can lead to desminopathies, a group of diseases characterized by variable and often severe cardiomyopathies along with skeletal muscle disorders. The basic desmin intermediate filament structure is composed of four segments separated by linkers that further assemble into dimers, tetramers and eventually unit-length filaments that compact radially to give the final form of the filament. Each step in this process is critical for proper filament formation and allow specific interactions within the cell. Mutations within the desmin gene can disrupt filament formation, as seen by aggregate formation, and thus have severe cardiac and skeletal outcomes, depending on the locus of the mutation. The focus of this review is to outline the cardiac molecular consequences of mutations located in the C-terminal part of segment 2B. This region is crucial for ensuring proper desmin filament formation and is a known hotspot for mutations that significantly impact cardiac function.
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Affiliation(s)
- Michelle Geryk
- Nantes Université, CNRS, INSERM, L'institut du thorax, Nantes, F-44000, France
| | - Flavien Charpentier
- Nantes Université, CNRS, INSERM, L'institut du thorax, Nantes, F-44000, France
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3
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Noureddine M, Gehmlich K. Structural and signaling proteins in the Z-disk and their role in cardiomyopathies. Front Physiol 2023; 14:1143858. [PMID: 36935760 PMCID: PMC10017460 DOI: 10.3389/fphys.2023.1143858] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
The sarcomere is the smallest functional unit of muscle contraction. It is delineated by a protein-rich structure known as the Z-disk, alternating with M-bands. The Z-disk anchors the actin-rich thin filaments and plays a crucial role in maintaining the mechanical stability of the cardiac muscle. A multitude of proteins interact with each other at the Z-disk and they regulate the mechanical properties of the thin filaments. Over the past 2 decades, the role of the Z-disk in cardiac muscle contraction has been assessed widely, however, the impact of genetic variants in Z-disk proteins has still not been fully elucidated. This review discusses the various Z-disk proteins (alpha-actinin, filamin C, titin, muscle LIM protein, telethonin, myopalladin, nebulette, and nexilin) and Z-disk-associated proteins (desmin, and obscurin) and their role in cardiac structural stability and intracellular signaling. This review further explores how genetic variants of Z-disk proteins are linked to inherited cardiac conditions termed cardiomyopathies.
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Affiliation(s)
- Maya Noureddine
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine and British Heart Foundation Centre of Research Excellence Oxford, University of Oxford, Oxford, United Kingdom
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4
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Onore ME, Savarese M, Picillo E, Passamano L, Nigro V, Politano L. Bi-Allelic DES Gene Variants Causing Autosomal Recessive Myofibrillar Myopathies Affecting Both Skeletal Muscles and Cardiac Function. Int J Mol Sci 2022; 23:ijms232415906. [PMID: 36555543 PMCID: PMC9785402 DOI: 10.3390/ijms232415906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/09/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
Mutations in the human desmin gene (DES) may cause both autosomal dominant and recessive cardiomyopathies leading to heart failure, arrhythmias and atrio-ventricular blocks, or progressive myopathies. Cardiac conduction disorders, arrhythmias and cardiomyopathies usually associated with progressive myopathy are the main manifestations of autosomal dominant desminopathies, due to mono-allelic pathogenic variants. The recessive forms, due to bi-allelic variants, are very rare and exhibit variable phenotypes in which premature sudden cardiac death could also occur in the first or second decade of life. We describe a further case of autosomal recessive desminopathy in an Italian boy born of consanguineous parents, who developed progressive myopathy at age 12, and dilated cardiomyopathy four years later and died of intractable heart failure at age 17. Next Generation Sequencing (NGS) analysis identified the homozygous loss-of-function variant c.634C>T; p.Arg212*, which was likely inherited from both parents. Furthermore, we performed a comparison of clinical and genetic results observed in our patient with those of cases so far reported in the literature.
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Affiliation(s)
- Maria Elena Onore
- Medical Genetics and Cardiomyology, Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 80138 Napoli, Italy
| | - Marco Savarese
- Folkhälsan Research Center, 00280 Helsinki, Finland
- Department of Medical and Clinical Genetics, Medicum, University of Helsinki, 00280 Helsinki, Finland
| | - Esther Picillo
- Medical Genetics and Cardiomyology, Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 80138 Napoli, Italy
| | - Luigia Passamano
- Medical Genetics and Cardiomyology, Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 80138 Napoli, Italy
| | - Vincenzo Nigro
- Medical Genetics and Cardiomyology, Department of Precision Medicine, University of Campania “Luigi Vanvitelli”, 80138 Napoli, Italy
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Luisa Politano
- Cardiomyology and Medical Genetics, Department of Experimental Medicine, University of Campania “Luigi Vanvitelli”, 80138 Napoli, Italy
- Correspondence:
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The N-Terminal Part of the 1A Domain of Desmin Is a Hot Spot Region for Putative Pathogenic DES Mutations Affecting Filament Assembly. Cells 2022; 11:cells11233906. [PMID: 36497166 PMCID: PMC9738904 DOI: 10.3390/cells11233906] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 11/29/2022] [Indexed: 12/09/2022] Open
Abstract
Desmin is the major intermediate filament protein of all three muscle cell types, and connects different cell organelles and multi-protein complexes such as the cardiac desmosomes. Several pathogenic mutations in the DES gene cause different skeletal and cardiac myopathies. However, the significance of the majority of DES missense variants is currently unknown, since functional data are lacking. To determine whether desmin missense mutations within the highly conserved 1A coil domain cause a filament assembly defect, we generated a set of variants with unknown significance and systematically analyzed the filament assembly using confocal microscopy in transfected SW-13, H9c2 cells and cardiomyocytes derived from induced pluripotent stem cells. We found that mutations in the N-terminal part of the 1A coil domain affect filament assembly, leading to cytoplasmic desmin aggregation. In contrast, mutant desmin in the C-terminal part of the 1A coil domain forms filamentous structures comparable to wild-type desmin. Our findings suggest that the N-terminal part of the 1A coil domain is a hot spot for pathogenic desmin mutations, which affect desmin filament assembly. This study may have relevance for the genetic counselling of patients carrying variants in the 1A coil domain of the DES gene.
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Liu YX, Yu R, Sheng Y, Fan LL, Deng Y. Case report: Whole-exome sequencing identifies a novel DES mutation (p. E434K) in a Chinese family with cardiomyopathy and sudden cardiac death. Front Cardiovasc Med 2022; 9:971501. [PMID: 36277747 PMCID: PMC9580399 DOI: 10.3389/fcvm.2022.971501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 09/05/2022] [Indexed: 11/13/2022] Open
Abstract
Background Desmin is an intermediate filament protein that plays a critical role in the stabilization of the sarcomeres and cell contacts in the cardiac intercalated disk. Mutated DES gene can cause hereditary cardiomyopathy with heterogeneous phenotypes, while the underlying molecular mechanisms requires further investigation. Methods We described a Chinese family present with cardiomyopathy and sudden cardiac death (SCD). Whole-exome sequencing (WES) and bioinformatics strategies were employed to explore the genetic entity of this family. Results An unknown heterozygote missense variant (c.1300G > A; p. E434K) of DES gene was identified. The mutation cosegregates in this family. The mutation was predicted as pathogenic and was absent in our 200 healthy controls. Conclusion We identified a novel DES mutation (p. E434K) in a Chinese family with cardiomyopathy and SCD. Our study not only provided a new case for the study of the relationship between DES mutations and hereditary cardiomyopathy but also broadened the spectrum of DES mutations.
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Affiliation(s)
- Yu-Xing Liu
- Department of Cardiovascular Surgery, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China,Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China,Hunan Key Laboratory of Animal Models for Human Disease, School of Life Sciences, Central South University, Changsha, China
| | - Rong Yu
- Department of Anesthesiology, The Second Xiangya Hospital, Central South University, Changsha, China
| | - Yue Sheng
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China,Hunan Key Laboratory of Animal Models for Human Disease, School of Life Sciences, Central South University, Changsha, China
| | - Liang-Liang Fan
- Department of Cardiovascular Surgery, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China,Department of Cell Biology, School of Life Sciences, Central South University, Changsha, China,Hunan Key Laboratory of Animal Models for Human Disease, School of Life Sciences, Central South University, Changsha, China,*Correspondence: Liang-Liang Fan,
| | - Yao Deng
- Department of Cardiovascular Surgery, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China,Yao Deng,
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Claes L, Schil KV, Dewals W, Beysen D. A Severe Form of Familial Desminopathy Due to a Homozygous Nonsense DES Variant in Two Siblings. Neuropediatrics 2022. [PMID: 35675837 DOI: 10.1055/a-1871-3692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Familial primary desminopathies are usually autosomal dominantly inherited and present at the age of 20 to 40 years with progressive muscle weakness and atrophy, cardiomyopathy, and cardiac arrhythmias. Cardiac features may precede the muscular weakness. Here, we report the rare case of two siblings presenting with a desminopathy at pediatric age, due to homozygous nonsense variations (c.700G > T [p.Glu234Ter]) in DES, representing an autosomal recessive inheritance pattern. The homozygous state of these variants is expected to result in the complete absence of desmin production. Rare autosomal recessive DES variants are associated with an earlier clinical presentation (from childhood to early adulthood) and faster evolution compared with more common autosomal dominant variants. A normal resting electrocardiography (ECG) and cardiac ultrasound can be a pitfall, as seen in our patient who has extensive fibrotic scarring on cardiac magnetic resonance imaging (MRI). We recommend yearly cardiac ultrasound, yearly 24-hour Holter monitoring and 2 yearly cardiac MRI from the age of 10 years in all asymptomatic patients. Heterozygous patients usually have no or only mild complaints but, though not yet reported in autosomal recessive desminopathies, muscular complaints are possible, as seen in the father of our patients. The prognosis for these patients with desminopathy presenting in childhood is unpredictable but anticipated as poor.
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Affiliation(s)
- Laura Claes
- Department of Paediatric Neurology, Antwerp University Hospital, Antwerp, Belgium
| | - Kristof van Schil
- Department of Medical Genetics, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.,Department of Medical Genetics, Antwerp University Hospital, Antwerp, Belgium
| | - Wendy Dewals
- Department of Paediatric Cardiology, Antwerp University Hospital, Antwerp, Belgium
| | - Diane Beysen
- Department of Paediatric Neurology, Antwerp University Hospital, Antwerp, Belgium.,Department of Paediatrics, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
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Silva AMS, Rodrigo P, Moreno CAM, Mendonça RDH, Estephan EDP, Camelo CG, Campos ED, Dias AT, Nascimento AM, Kulikowski LD, Oliveira ASB, Reed UC, Goldfarb LG, Olivé M, Zanoteli E. The Location of Disease-Causing DES Variants Determines the Severity of Phenotype and the Morphology of Sarcoplasmic Aggregates. J Neuropathol Exp Neurol 2022; 81:746-757. [PMID: 35898174 DOI: 10.1093/jnen/nlac063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Desmin (DES) is the main intermediate muscle filament that connects myofibrils individually and with the nucleus, sarcolemma, and organelles. Pathogenic variants of DES cause desminopathy, a disorder affecting the heart and skeletal muscles. We aimed to analyze the clinical features, morphology, and distribution of desmin aggregates in skeletal muscle biopsies of patients with desminopathy and to correlate these findings with the type and location of disease-causing DES variants. This retrospective study included 30 patients from 20 families with molecularly confirmed desminopathy from 2 neuromuscular referral centers. We identified 2 distinct patterns of desmin aggregates: well-demarcated subsarcolemmal aggregates and diffuse aggregates with poorly delimited borders. Pathogenic variants located in the 1B segment and the tail domain of the desmin molecule are more likely to present with early-onset cardiomyopathy compared to patients with variants in other segments. All patients with mutations in the 1B segment had well-demarcated subsarcolemmal aggregates, but none of the patients with variants in other desmin segments showed such histological features. We suggest that variants located in the 1B segment lead to well-shaped subsarcolemmal desmin aggregation and cause disease with more frequent cardiac manifestations. These findings will facilitate early identification of patients with potentially severe cardiac syndromes.
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Affiliation(s)
| | - Patricia Rodrigo
- Neuropathology Unit, Department of Pathology and Neuromuscular Unit, Department of Neurology, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain
| | | | | | - Eduardo de Paula Estephan
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Clara Gontijo Camelo
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Eliene Dutra Campos
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Alexandre Torchio Dias
- Department of Pathology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Amom Mendes Nascimento
- Department of Pathology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | | | - Acary Souza Bulle Oliveira
- Division of Neuromuscular Diseases, Department of Neurology and Neurosurgery, Universidade Federal de São Paulo (UNIFESP), São Paulo, SP, Brazil
| | - Umbertina Conti Reed
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
| | - Lev G Goldfarb
- Department of Pathology and Molecular Medicine, Queen's University, Kingston General Hospital, Kingston, Ontario, Canada
| | - Montse Olivé
- Neuropathology Unit, Department of Pathology and Neuromuscular Unit, Department of Neurology, IDIBELL-Hospital Universitari de Bellvitge, Barcelona, Spain
| | - Edmar Zanoteli
- Department of Neurology, Faculdade de Medicina, Universidade de São Paulo (FMUSP), São Paulo, Brazil
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Cardiac Filaminopathies: Illuminating the Divergent Role of Filamin C Mutations in Human Cardiomyopathy. J Clin Med 2021; 10:jcm10040577. [PMID: 33557094 PMCID: PMC7913873 DOI: 10.3390/jcm10040577] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 01/07/2023] Open
Abstract
Over the past decades, there has been tremendous progress in understanding genetic alterations that can result in different phenotypes of human cardiomyopathies. More than a thousand mutations in various genes have been identified, indicating that distinct genetic alterations, or combinations of genetic alterations, can cause either hypertrophic (HCM), dilated (DCM), restrictive (RCM), or arrhythmogenic cardiomyopathies (ARVC). Translation of these results from “bench to bedside” can potentially group affected patients according to their molecular etiology and identify subclinical individuals at high risk for developing cardiomyopathy or patients with overt phenotypes at high risk for cardiac deterioration or sudden cardiac death. These advances provide not only mechanistic insights into the earliest manifestations of cardiomyopathy, but such efforts also hold the promise that mutation-specific pathophysiology might result in novel “personalized” therapeutic possibilities. Recently, the FLNC gene encoding the sarcomeric protein filamin C has gained special interest since FLNC mutations were found in several distinct and possibly overlapping cardiomyopathy phenotypes. Specifically, mutations in FLNC were initially only linked to myofibrillar myopathy (MFM), but are now increasingly found in various forms of human cardiomyopathy. FLNC thereby represents another example for the complex genetic and phenotypic continuum of these diseases.
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10
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The Desmin ( DES) Mutation p.A337P Is Associated with Left-Ventricular Non-Compaction Cardiomyopathy. Genes (Basel) 2021; 12:genes12010121. [PMID: 33478057 PMCID: PMC7835827 DOI: 10.3390/genes12010121] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/04/2021] [Accepted: 01/15/2021] [Indexed: 02/06/2023] Open
Abstract
Here, we present a small Russian family, where the index patient received a diagnosis of left-ventricular non-compaction cardiomyopathy (LVNC) in combination with a skeletal myopathy. Clinical follow-up analysis revealed a LVNC phenotype also in her son. Therefore, we applied a broad next-generation sequencing gene panel approach for the identification of the underlying mutation. Interestingly, DES-p.A337P was identified in the genomes of both patients, whereas only the index patient carried DSP-p.L1348X. DES encodes the muscle-specific intermediate filament protein desmin and DSP encodes desmoplakin, which is a cytolinker protein connecting desmosomes with the intermediate filaments. Because the majority of DES mutations cause severe filament assembly defects and because this mutation was found in both affected patients, we analyzed this DES mutation in vitro by cell transfection experiments in combination with confocal microscopy. Of note, desmin-p.A337P forms cytoplasmic aggregates in transfected SW-13 cells and in cardiomyocytes derived from induced pluripotent stem cells underlining its pathogenicity. In conclusion, we suggest including the DES gene in the genetic analysis for LVNC patients in the future, especially if clinical involvement of the skeletal muscle is present.
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11
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Hypertrophic Cardiomyopathy: Diverse Pathophysiology Revealed by Genetic Research, Toward Future Therapy. Keio J Med 2020; 69:77-87. [PMID: 32224552 DOI: 10.2302/kjm.2019-0012-oa] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is an intractable disease that causes heart failure mainly due to unexplained severe cardiac hypertrophy and diastolic dysfunction. HCM, which occurs in 0.2% of the general population, is the most common cause of sudden cardiac death in young people. HCM has been studied extensively using molecular genetic approaches. Genes encoding cardiac β-myosin heavy chain, cardiac myosin-binding protein C, and troponin complex, which were originally identified as causative genes, were subsequently reported to be frequently implicated in HCM. Indeed, HCM has been considered a disease of sarcomere gene mutations. However, fewer than half of patients with HCM have mutations in sarcomere genes. The others have been documented to have mutations in cardiac proteins in various other locations, including the Z disc, sarcoplasmic reticulum, plasma membrane, nucleus, and mitochondria. Next-generation sequencing makes it possible to detect mutations at high throughput, and it has become increasingly common to identify multiple cardiomyopathy-causing gene mutations in a single HCM patient. Elucidating how mutations in different genes contribute to the disease pathophysiology will be a challenge. In studies using animal models, sarcomere mutations generally tend to increase myocardial Ca2+ sensitivity, and some mutations increase the activity of myosin ATPase. Clinical trials of drugs to treat HCM are ongoing, and further new therapies based on pathophysiological analyses of the causative genes are eagerly anticipated.
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12
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Gerull B, Brodehl A. Genetic Animal Models for Arrhythmogenic Cardiomyopathy. Front Physiol 2020; 11:624. [PMID: 32670084 PMCID: PMC7327121 DOI: 10.3389/fphys.2020.00624] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/18/2020] [Indexed: 12/12/2022] Open
Abstract
Arrhythmogenic cardiomyopathy has been clinically defined since the 1980s and causes right or biventricular cardiomyopathy associated with ventricular arrhythmia. Although it is a rare cardiac disease, it is responsible for a significant proportion of sudden cardiac deaths, especially in athletes. The majority of patients with arrhythmogenic cardiomyopathy carry one or more genetic variants in desmosomal genes. In the 1990s, several knockout mouse models of genes encoding for desmosomal proteins involved in cell-cell adhesion revealed for the first time embryonic lethality due to cardiac defects. Influenced by these initial discoveries in mice, arrhythmogenic cardiomyopathy received an increasing interest in human cardiovascular genetics, leading to the discovery of mutations initially in desmosomal genes and later on in more than 25 different genes. Of note, even in the clinic, routine genetic diagnostics are important for risk prediction of patients and their relatives with arrhythmogenic cardiomyopathy. Based on improvements in genetic animal engineering, different transgenic, knock-in, or cardiac-specific knockout animal models for desmosomal and nondesmosomal proteins have been generated, leading to important discoveries in this field. Here, we present an overview about the existing animal models of arrhythmogenic cardiomyopathy with a focus on the underlying pathomechanism and its importance for understanding of this disease. Prospectively, novel mechanistic insights gained from the whole animal, organ, tissue, cellular, and molecular levels will lead to the development of efficient personalized therapies for treatment of arrhythmogenic cardiomyopathy.
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Affiliation(s)
- Brenda Gerull
- Comprehensive Heart Failure Center Wuerzburg, Department of Internal Medicine I, University Hospital Würzburg, Würzburg, Germany.,Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Andreas Brodehl
- Erich and Hanna Klessmann Institute for Cardiovascular Research and Development, Heart and Diabetes Center NRW, University Hospitals of the Ruhr-University of Bochum, Bad Oeynhausen, Germany
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13
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Stöckigt F, Eichhorn L, Beiert T, Knappe V, Radecke T, Steinmetz M, Nickenig G, Peeva V, Kudin AP, Kunz WS, Berwanger C, Kamm L, Schultheis D, Schlötzer-Schrehardt U, Clemen CS, Schröder R, Schrickel JW. Heart failure after pressure overload in autosomal-dominant desminopathies: Lessons from heterozygous DES-p.R349P knock-in mice. PLoS One 2020; 15:e0228913. [PMID: 32126091 PMCID: PMC7053759 DOI: 10.1371/journal.pone.0228913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 01/27/2020] [Indexed: 11/21/2022] Open
Abstract
Background Mutations in the human desmin gene (DES) cause autosomal-dominant and -recessive cardiomyopathies, leading to heart failure, arrhythmias, and AV blocks. We analyzed the effects of vascular pressure overload in a patient-mimicking p.R349P desmin knock-in mouse model that harbors the orthologue of the frequent human DES missense mutation p.R350P. Methods and results Transverse aortic constriction (TAC) was performed on heterozygous (HET) DES-p.R349P mice and wild-type (WT) littermates. Echocardiography demonstrated reduced left ventricular ejection fraction in HET-TAC (WT-sham: 69.5 ± 2.9%, HET-sham: 64.5 ± 4.7%, WT-TAC: 63.5 ± 4.9%, HET-TAC: 55.7 ± 5.4%; p<0.01). Cardiac output was significantly reduced in HET-TAC (WT sham: 13088 ± 2385 μl/min, HET sham: 10391 ± 1349μl/min, WT-TAC: 8097 ± 1903μl/min, HET-TAC: 5793 ± 2517μl/min; p<0.01). Incidence and duration of AV blocks as well as the probability to induce ventricular tachycardias was highest in HET-TAC. We observed reduced mtDNA copy numbers in HET-TAC (WT-sham: 12546 ± 406, HET-sham: 13526 ± 781, WT-TAC: 11155 ± 3315, HET-TAC: 8649 ± 1582; p = 0.025), but no mtDNA deletions. The activity of respiratory chain complexes I and IV showed the greatest reductions in HET-TAC. Conclusion Pressure overload in HET mice aggravated the clinical phenotype of cardiomyopathy and resulted in mitochondrial dysfunction. Preventive avoidance of pressure overload/arterial hypertension in desminopathy patients might represent a crucial therapeutic measure.
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Affiliation(s)
- Florian Stöckigt
- Department of Cardiology, University Hospital Bonn, Bonn, Germany
- Department of Cardiology, Krankenhaus Porz, Urbacher Weg, Cologne, Germany
- * E-mail:
| | - Lars Eichhorn
- Department of Anesthesiology, University Hospital Bonn, Bonn, Germany
| | - Thomas Beiert
- Department of Cardiology, University Hospital Bonn, Bonn, Germany
| | - Vincent Knappe
- Department of Cardiology, University Hospital Bonn, Bonn, Germany
| | - Tobias Radecke
- Department of Cardiology, University Hospital Essen, Hufelandstraße, Essen, Germany
| | - Martin Steinmetz
- Department of Cardiology, University Hospital Essen, Hufelandstraße, Essen, Germany
| | - Georg Nickenig
- Department of Cardiology, University Hospital Bonn, Bonn, Germany
| | - Viktoriya Peeva
- Institute of Experimental Epileptology and Cognition Research, Bonn, Germany
- Department of Epileptology, University Hospital of Bonn, Bonn, Germany
| | - Alexei P. Kudin
- Institute of Experimental Epileptology and Cognition Research, Bonn, Germany
- Department of Epileptology, University Hospital of Bonn, Bonn, Germany
| | - Wolfram S. Kunz
- Institute of Experimental Epileptology and Cognition Research, Bonn, Germany
- Department of Epileptology, University Hospital of Bonn, Bonn, Germany
| | - Carolin Berwanger
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Linder Höhe, Cologne, Germany
| | - Lisa Kamm
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Schwabachanlage, Erlangen, Germany
| | - Dorothea Schultheis
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Schwabachanlage, Erlangen, Germany
| | - Ursula Schlötzer-Schrehardt
- Department of Opthalmology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Schwabachanlage, Erlangen, Germany
| | - Christoph S. Clemen
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Linder Höhe, Cologne, Germany
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Schwabachanlage, Erlangen, Germany
- Center for Biochemistry, Institute of Biochemistry I, Medical Faculty, University of Cologne, Cologne, Germany
- Center for Physiology and Pathophysiology, Institute of Vegetative Physiology, Medical Faculty, University of Cologne, Cologne, Germany
| | - Rolf Schröder
- Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Schwabachanlage, Erlangen, Germany
| | - Jan W. Schrickel
- Department of Cardiology, University Hospital Bonn, Bonn, Germany
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Mukund K, Subramaniam S. Skeletal muscle: A review of molecular structure and function, in health and disease. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2020; 12:e1462. [PMID: 31407867 PMCID: PMC6916202 DOI: 10.1002/wsbm.1462] [Citation(s) in RCA: 233] [Impact Index Per Article: 58.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 07/03/2019] [Accepted: 07/03/2019] [Indexed: 12/11/2022]
Abstract
Decades of research in skeletal muscle physiology have provided multiscale insights into the structural and functional complexity of this important anatomical tissue, designed to accomplish the task of generating contraction, force and movement. Skeletal muscle can be viewed as a biomechanical device with various interacting components including the autonomic nerves for impulse transmission, vasculature for efficient oxygenation, and embedded regulatory and metabolic machinery for maintaining cellular homeostasis. The "omics" revolution has propelled a new era in muscle research, allowing us to discern minute details of molecular cross-talk required for effective coordination between the myriad interacting components for efficient muscle function. The objective of this review is to provide a systems-level, comprehensive mapping the molecular mechanisms underlying skeletal muscle structure and function, in health and disease. We begin this review with a focus on molecular mechanisms underlying muscle tissue development (myogenesis), with an emphasis on satellite cells and muscle regeneration. We next review the molecular structure and mechanisms underlying the many structural components of the muscle: neuromuscular junction, sarcomere, cytoskeleton, extracellular matrix, and vasculature surrounding muscle. We highlight aberrant molecular mechanisms and their possible clinical or pathophysiological relevance. We particularly emphasize the impact of environmental stressors (inflammation and oxidative stress) in contributing to muscle pathophysiology including atrophy, hypertrophy, and fibrosis. This article is categorized under: Physiology > Mammalian Physiology in Health and Disease Developmental Biology > Developmental Processes in Health and Disease Models of Systems Properties and Processes > Cellular Models.
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Affiliation(s)
- Kavitha Mukund
- Department of BioengineeringUniversity of CaliforniaSan DiegoCalifornia
| | - Shankar Subramaniam
- Department of Bioengineering, Bioinformatics & Systems BiologyUniversity of CaliforniaSan DiegoCalifornia
- Department of Computer Science and EngineeringUniversity of CaliforniaSan DiegoCalifornia
- Department of Cellular and Molecular Medicine and NanoengineeringUniversity of CaliforniaSan DiegoCalifornia
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15
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Restrictive Cardiomyopathy is Caused by a Novel Homozygous Desmin ( DES) Mutation p.Y122H Leading to a Severe Filament Assembly Defect. Genes (Basel) 2019; 10:genes10110918. [PMID: 31718026 PMCID: PMC6896098 DOI: 10.3390/genes10110918] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 11/05/2019] [Accepted: 11/08/2019] [Indexed: 12/29/2022] Open
Abstract
Here, we present a small Iranian family, where the index patient received a diagnosis of restrictive cardiomyopathy (RCM) in combination with atrioventricular (AV) block. Genetic analysis revealed a novel homozygous missense mutation in the DES gene (c.364T > C; p.Y122H), which is absent in human population databases. The mutation is localized in the highly conserved coil-1 desmin subdomain. In silico, prediction tools indicate a deleterious effect of the desmin (DES) mutation p.Y122H. Consequently, we generated an expression plasmid encoding the mutant and wildtype desmin formed, and analyzed the filament formation in vitro in cardiomyocytes derived from induced pluripotent stem cells and HT-1080 cells. Confocal microscopy revealed a severe filament assembly defect of mutant desmin supporting the pathogenicity of the DES mutation, p.Y122H, whereas the wildtype desmin formed regular intermediate filaments. According to the guidelines of the American College of Medical Genetics and Genomics, we classified this mutation, therefore, as a novel pathogenic mutation. Our report could point to a recessive inheritance of the DES mutation, p.Y122H, which is important for the genetic counseling of similar families with restrictive cardiomyopathy caused by DES mutations.
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Brodehl A, Ebbinghaus H, Deutsch MA, Gummert J, Gärtner A, Ratnavadivel S, Milting H. Human Induced Pluripotent Stem-Cell-Derived Cardiomyocytes as Models for Genetic Cardiomyopathies. Int J Mol Sci 2019; 20:ijms20184381. [PMID: 31489928 PMCID: PMC6770343 DOI: 10.3390/ijms20184381] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/29/2019] [Accepted: 09/03/2019] [Indexed: 12/17/2022] Open
Abstract
In the last few decades, many pathogenic or likely pathogenic genetic mutations in over hundred different genes have been described for non-ischemic, genetic cardiomyopathies. However, the functional knowledge about most of these mutations is still limited because the generation of adequate animal models is time-consuming and challenging. Therefore, human induced pluripotent stem cells (iPSCs) carrying specific cardiomyopathy-associated mutations are a promising alternative. Since the original discovery that pluripotency can be artificially induced by the expression of different transcription factors, various patient-specific-induced pluripotent stem cell lines have been generated to model non-ischemic, genetic cardiomyopathies in vitro. In this review, we describe the genetic landscape of non-ischemic, genetic cardiomyopathies and give an overview about different human iPSC lines, which have been developed for the disease modeling of inherited cardiomyopathies. We summarize different methods and protocols for the general differentiation of human iPSCs into cardiomyocytes. In addition, we describe methods and technologies to investigate functionally human iPSC-derived cardiomyocytes. Furthermore, we summarize novel genome editing approaches for the genetic manipulation of human iPSCs. This review provides an overview about the genetic landscape of inherited cardiomyopathies with a focus on iPSC technology, which might be of interest for clinicians and basic scientists interested in genetic cardiomyopathies.
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Affiliation(s)
- Andreas Brodehl
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Hans Ebbinghaus
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Marcus-André Deutsch
- Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, University Hospital Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Jan Gummert
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
- Department of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, University Hospital Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Anna Gärtner
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Sandra Ratnavadivel
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Center NRW, University Hospital of the Ruhr-University Bochum, Georgstrasse 11, D-32545 Bad Oeynhausen, Germany.
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Recessive DES cardio/myopathy without myofibrillar aggregates: intronic splice variant silences one allele leaving only missense L190P-desmin. Eur J Hum Genet 2019; 27:1267-1273. [PMID: 31024060 DOI: 10.1038/s41431-019-0393-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 03/04/2019] [Accepted: 03/19/2019] [Indexed: 01/08/2023] Open
Abstract
We establish autosomal recessive DES variants p.(Leu190Pro) and a deep intronic splice variant causing inclusion of a frameshift-inducing artificial exon/intronic fragment, as the likely cause of myopathy with cardiac involvement in female siblings. Both sisters presented in their twenties with slowly progressive limb girdle weakness, severe systolic dysfunction, and progressive, severe respiratory weakness. Desmin is an intermediate filament protein typically associated with autosomal dominant myofibrillar myopathy with cardiac involvement. However a few rare cases of autosomal recessive desminopathy are reported. In this family, a paternal missense p.(Leu190Pro) variant was viewed unlikely to be causative of autosomal dominant desminopathy, as the father and brothers carrying this variant were clinically unaffected. Clinical fit with a DES-related myopathy encouraged closer scrutiny of all DES variants, identifying a maternal deep intronic variant within intron-7, predicted to create a cryptic splice site, which segregated with disease. RNA sequencing and studies of muscle cDNA confirmed the deep intronic variant caused aberrant splicing of an artificial exon/intronic fragment into maternal DES mRNA transcripts, encoding a premature termination codon, and potently activating nonsense-mediate decay (92% paternal DES transcripts, 8% maternal). Western blot showed 60-75% reduction in desmin levels, likely comprised only of missense p.(Leu190Pro) desmin. Biopsy showed fibre size variation with increased central nuclei. Electron microscopy showed extensive myofibrillar disarray, duplication of the basal lamina, but no inclusions or aggregates. This study expands the phenotypic spectrum of recessive DES cardio/myopathy, and emphasizes the continuing importance of muscle biopsy for functional genomics pursuit of 'tricky' variants in neuromuscular conditions.
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Brodehl A, Gaertner-Rommel A, Milting H. Molecular insights into cardiomyopathies associated with desmin (DES) mutations. Biophys Rev 2018; 10:983-1006. [PMID: 29926427 DOI: 10.1007/s12551-018-0429-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 05/22/2018] [Indexed: 12/15/2022] Open
Abstract
Increasing usage of next-generation sequencing techniques pushed during the last decade cardiogenetic diagnostics leading to the identification of a huge number of genetic variants in about 170 genes associated with cardiomyopathies, channelopathies, or syndromes with cardiac involvement. Because of the biochemical and cellular complexity, it is challenging to understand the clinical meaning or even the relevant pathomechanisms of the majority of genetic sequence variants. However, detailed knowledge about the associated molecular pathomechanism is essential for the development of efficient therapeutic strategies in future and genetic counseling. Mutations in DES, encoding the muscle-specific intermediate filament protein desmin, have been identified in different kinds of cardiac and skeletal myopathies. Here, we review the functions of desmin in health and disease with a focus on cardiomyopathies. In addition, we will summarize the genetic and clinical literature about DES mutations and will explain relevant cell and animal models. Moreover, we discuss upcoming perspectives and consequences of novel experimental approaches like genome editing technology, which might open a novel research field contributing to the development of efficient and mutation-specific treatment options.
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Affiliation(s)
- Andreas Brodehl
- Erich and Hanna Klessmann Institute for Cardiovascular Research & Development, Heart and Diabetes Centre NRW, Ruhr-University Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany.
| | - Anna Gaertner-Rommel
- Erich and Hanna Klessmann Institute for Cardiovascular Research & Development, Heart and Diabetes Centre NRW, Ruhr-University Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute for Cardiovascular Research & Development, Heart and Diabetes Centre NRW, Ruhr-University Bochum, Georgstrasse 11, 32545, Bad Oeynhausen, Germany.
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Genetic background of Japanese patients with pediatric hypertrophic and restrictive cardiomyopathy. J Hum Genet 2018; 63:989-996. [PMID: 29907873 DOI: 10.1038/s10038-018-0479-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 01/28/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM) present a high risk for sudden cardiac death in pediatric patients. The aim of this study was to identify disease-associated genetic variants in Japanese patients with pediatric HCM and RCM. We analyzed 67 cardiomyopathy-associated genes in 46 HCM and 7 RCM patients diagnosed before 16 years of age using a next-generation sequencing system. We found that 78% of HCM and 71% of RCM patients carried disease-associated genetic variants. Disease-associated genetic variants were identified in 80% of HCM patients with a family history and in 77% of HCM patients with no apparent family history (NFH). MYH7 and/or MYBPC3 variants comprised 76% of HCM-associated variants, whereas troponin complex-encoding genes comprised 75% of the RCM-associated variants. In addition, 91% of HCM patients with implantable cardioverter-defibrillators and infant cases had NFH, and the 88% of HCM patients carrying disease-associated genetic variants were males who carried MYH7 or MYBPC3 variants. Moreover, two disease-associated LAMP2, one DES and one FHOD3 variants, were identified in HCM patients. In this study, pediatric HCM and RCM patients were found to carry disease-associated genetic variants at a high rate. Most of the variants were in MYH7 or MYPBC3 for HCM and TNNT2 or TNNI3 for RCM.
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