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Sellung D, Heil L, Daya N, Jacobsen F, Mertens-Rill J, Zhuge H, Döring K, Piran M, Milting H, Unger A, Linke WA, Kley R, Preusse C, Roos A, Fürst DO, Ven PFMVD, Vorgerd M. Novel Filamin C Myofibrillar Myopathy Variants Cause Different Pathomechanisms and Alterations in Protein Quality Systems. Cells 2023; 12:cells12091321. [PMID: 37174721 PMCID: PMC10177260 DOI: 10.3390/cells12091321] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/28/2023] [Accepted: 05/03/2023] [Indexed: 05/15/2023] Open
Abstract
Myofibrillar myopathies (MFM) are a group of chronic muscle diseases pathophysiologically characterized by accumulation of protein aggregates and structural failure of muscle fibers. A subtype of MFM is caused by heterozygous mutations in the filamin C (FLNC) gene, exhibiting progressive muscle weakness, muscle structural alterations and intracellular protein accumulations. Here, we characterize in depth the pathogenicity of two novel truncating FLNc variants (p.Q1662X and p.Y2704X) and assess their distinct effect on FLNc stability and distribution as well as their impact on protein quality system (PQS) pathways. Both variants cause a slowly progressive myopathy with disease onset in adulthood, chronic myopathic alterations in muscle biopsy including the presence of intracellular protein aggregates. Our analyses revealed that p.Q1662X results in FLNc haploinsufficiency and p.Y2704X in a dominant-negative FLNc accumulation. Moreover, both protein-truncating variants cause different PQS alterations: p.Q1662X leads to an increase in expression of several genes involved in the ubiquitin-proteasome system (UPS) and the chaperone-assisted selective autophagy (CASA) system, whereas p.Y2704X results in increased abundance of proteins involved in UPS activation and autophagic buildup. We conclude that truncating FLNC variants might have different pathogenetic consequences and impair PQS function by diverse mechanisms and to varying extents. Further studies on a larger number of patients are necessary to confirm our observations.
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Affiliation(s)
- Dominik Sellung
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Lorena Heil
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Nassam Daya
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Frank Jacobsen
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Janine Mertens-Rill
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Heidi Zhuge
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Kristina Döring
- Department of Human Genetics, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Misagh Piran
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | - Hendrik Milting
- Erich and Hanna Klessmann Institute, Heart and Diabetes Centre NRW, University Hospital of the Ruhr-University Bochum, 32545 Bad Oeynhausen, Germany
| | - Andreas Unger
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Wolfgang A Linke
- Institute of Physiology II, University of Münster, 48149 Münster, Germany
| | - Rudi Kley
- Department of Neurology and Clinical Neurophysiology, St. Marien-Hospital Borken, 46325 Borken, Germany
| | - Corinna Preusse
- Department of Neuropathology, Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
| | - Andreas Roos
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
| | - Dieter O Fürst
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Peter F M van der Ven
- Department of Molecular Cell Biology, Institute for Cell Biology, University of Bonn, 53121 Bonn, Germany
| | - Matthias Vorgerd
- Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr-University Bochum, 44789 Bochum, Germany
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2
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Expression of LIM domain-binding 3 (LDB3), a striated muscle Z-band alternatively spliced PDZ-motif protein in the nervous system. Sci Rep 2023; 13:270. [PMID: 36609526 PMCID: PMC9822979 DOI: 10.1038/s41598-023-27531-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 01/03/2023] [Indexed: 01/07/2023] Open
Abstract
LIM domain-binding 3 (LDB3) is a member of the Enigma family of PDZ-LIM proteins. LDB3 has been reported as a striated muscle-specific Z-band alternatively spliced protein that plays an important role in mechanosensory actin cytoskeleton remodeling. This study shows that LDB3 is broadly expressed in the central and peripheral nervous system of human and mouse. LDB3 is predominantly expressed in the adult stages compared to early development and at a significantly higher level in the spinal cord than in the brain. As in skeletal muscle and heart, LDB3 is extensively alternatively spliced in the neurons. Three novel splice isoforms were identified suggesting splicing-dependent regulation of LDB3 expression in the nervous system. Expression of LDB3 in the motor cortex, cerebellum, spinal motor neuron, peripheral nerve, and neuromuscular junction in addition to skeletal muscle indicates important roles for this PDZ-LIM family protein in motor planning and execution. Moreover, expression in the hippocampal neurons suggests roles for LDB3 in learning and memory. LDB3 interactors filamin C and myotilin are also expressed in the spinal motor neuron, nerve, and neuromuscular junction, thereby providing the basis for neurogenic manifestations in myopathies associated with mutations in these so-called muscle proteins.
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3
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Muravyev A, Vershinina T, Tesner P, Sjoberg G, Fomicheva Y, Čajbiková NN, Kozyreva A, Zhuk S, Mamaeva E, Tarnovskaya S, Jornholt J, Sokolnikova P, Pervunina T, Vasichkina E, Sejersen T, Kostareva A. Rare clinical phenotype of filaminopathy presenting as restrictive cardiomyopathy and myopathy in childhood. Orphanet J Rare Dis 2022; 17:358. [PMID: 36104822 PMCID: PMC9476594 DOI: 10.1186/s13023-022-02477-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 08/13/2022] [Indexed: 11/10/2022] Open
Abstract
Background FLNC is one of the few genes associated with all types of cardiomyopathies, but it also underlies neuromuscular phenotype. The combination of concomitant neuromuscular and cardiac involvement is not often observed in filaminopathies and the impact of this on the disease prognosis has hitherto not been analyzed. Results Here we provide a detailed clinical, genetic, and structural prediction analysis of distinct FLNC-associated phenotypes based on twelve pediatric cases. They include early-onset restrictive cardiomyopathy (RCM) in association with congenital myopathy. In all patients the initial diagnosis was established during the first year of life and in five out of twelve (41.7%) patients the first symptoms were observed at birth. RCM was present in all patients, often in combination with septal defects. No ventricular arrhythmias were noted in any of the patients presented here. Myopathy was confirmed by neurological examination, electromyography, and morphological studies. Arthrogryposes was diagnosed in six patients and remained clinically meaningful with increasing age in three of them. One patient underwent successful heart transplantation at the age of 18 years and two patients are currently included in the waiting list for heart transplantation. Two died due to congestive heart failure. One patient had ICD instally as primary prevention of SCD. In ten out of twelve patients the disease was associated with missense variants and only in two cases loss of function variants were detected. In half of the described cases, an amino acid substitution A1186V, altering the structure of IgFLNc10, was found. Conclusions The present description of twelve cases of early-onset restrictive cardiomyopathy with congenital myopathy and FLNC mutation, underlines a distinct unique phenotype that can be suggested as a separate clinical form of filaminopathies. Amino acid substitution A1186V, which was observed in half of the cases, defines a mutational hotspot for the reported combination of myopathy and cardiomyopathy. Several independent molecular mechanisms of FLNC mutations linked to filamin structure and function can explain the broad spectrum of FLNC-associated phenotypes. Early disease presentation and unfavorable prognosis of heart failure demanding heart transplantation make awareness of this clinical form of filaminopathy of great clinical importance. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-022-02477-5.
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4
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The Role of Z-disc Proteins in Myopathy and Cardiomyopathy. Int J Mol Sci 2021; 22:ijms22063058. [PMID: 33802723 PMCID: PMC8002584 DOI: 10.3390/ijms22063058] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/07/2021] [Accepted: 03/11/2021] [Indexed: 12/11/2022] Open
Abstract
The Z-disc acts as a protein-rich structure to tether thin filament in the contractile units, the sarcomeres, of striated muscle cells. Proteins found in the Z-disc are integral for maintaining the architecture of the sarcomere. They also enable it to function as a (bio-mechanical) signalling hub. Numerous proteins interact in the Z-disc to facilitate force transduction and intracellular signalling in both cardiac and skeletal muscle. This review will focus on six key Z-disc proteins: α-actinin 2, filamin C, myopalladin, myotilin, telethonin and Z-disc alternatively spliced PDZ-motif (ZASP), which have all been linked to myopathies and cardiomyopathies. We will summarise pathogenic variants identified in the six genes coding for these proteins and look at their involvement in myopathy and cardiomyopathy. Listing the Minor Allele Frequency (MAF) of these variants in the Genome Aggregation Database (GnomAD) version 3.1 will help to critically re-evaluate pathogenicity based on variant frequency in normal population cohorts.
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Savarese M, Sarparanta J, Vihola A, Jonson PH, Johari M, Rusanen S, Hackman P, Udd B. Panorama of the distal myopathies. ACTA MYOLOGICA : MYOPATHIES AND CARDIOMYOPATHIES : OFFICIAL JOURNAL OF THE MEDITERRANEAN SOCIETY OF MYOLOGY 2020; 39:245-265. [PMID: 33458580 PMCID: PMC7783427 DOI: 10.36185/2532-1900-028] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 11/11/2020] [Indexed: 12/15/2022]
Abstract
Distal myopathies are genetic primary muscle disorders with a prominent weakness at onset in hands and/or feet. The age of onset (from early childhood to adulthood), the distribution of muscle weakness (upper versus lower limbs) and the histological findings (ranging from nonspecific myopathic changes to myofibrillar disarrays and rimmed vacuoles) are extremely variable. However, despite being characterized by a wide clinical and genetic heterogeneity, the distal myopathies are a category of muscular dystrophies: genetic diseases with progressive loss of muscle fibers. Myopathic congenital arthrogryposis is also a form of distal myopathy usually caused by focal amyoplasia. Massive parallel sequencing has further expanded the long list of genes associated with a distal myopathy, and contributed identifying as distal myopathy-causative rare variants in genes more often related with other skeletal or cardiac muscle diseases. Currently, almost 20 genes (ACTN2, CAV3, CRYAB, DNAJB6, DNM2, FLNC, HNRNPA1, HSPB8, KHLH9, LDB3, MATR3, MB, MYOT, PLIN4, TIA1, VCP, NOTCH2NLC, LRP12, GIPS1) have been associated with an autosomal dominant form of distal myopathy. Pathogenic changes in four genes (ADSSL, ANO5, DYSF, GNE) cause an autosomal recessive form; and disease-causing variants in five genes (DES, MYH7, NEB, RYR1 and TTN) result either in a dominant or in a recessive distal myopathy. Finally, a digenic mechanism, underlying a Welander-like form of distal myopathy, has been recently elucidated. Rare pathogenic mutations in SQSTM1, previously identified with a bone disease (Paget disease), unexpectedly cause a distal myopathy when combined with a common polymorphism in TIA1. The present review aims at describing the genetic basis of distal myopathy and at summarizing the clinical features of the different forms described so far.
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Affiliation(s)
- Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Jaakko Sarparanta
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Anna Vihola
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Neuromuscular Research Center, Department of Genetics, Fimlab Laboratories, Tampere, Finland
| | - Per Harald Jonson
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Mridul Johari
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Salla Rusanen
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Peter Hackman
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland
- Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
- Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
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6
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Luo YB, Peng Y, Lu Y, Li Q, Duan H, Bi F, Yang H. Expanding the Clinico-Genetic Spectrum of Myofibrillar Myopathy: Experience From a Chinese Neuromuscular Center. Front Neurol 2020; 11:1014. [PMID: 33041974 PMCID: PMC7522348 DOI: 10.3389/fneur.2020.01014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 07/31/2020] [Indexed: 12/14/2022] Open
Abstract
Background: Myofibrillar myopathy is a group of hereditary neuromuscular disorders characterized by dissolution of myofibrils and abnormal intracellular accumulation of Z disc-related proteins. We aimed to characterize the clinical, physiological, pathohistological, and genetic features of Chinese myofibrillar myopathy patients from a single neuromuscular center. Methods: A total of 18 patients were enrolled. Demographic and clinical data were collected. Laboratory investigations, electromyography, and cardiac evaluation was performed. Routine and immunohistochemistry stainings against desmin, αB-crystallin, and BAG3 of muscle specimen were carried out. Finally, next-generation sequencing panel array for genes associated with hereditary neuromuscular disorders were performed. Results: Twelve pathogenic variants in DES, BAG3, FLNC, FHL1, and TTN were identified, of which seven were novel mutations. The novel DES c.1256C>T substitution is a high frequency mutation. The combined recessively/dominantly transmitted c.19993G>T and c.107545delG mutations in TTN gene cause a limb girdle muscular dystrophy phenotype with the classical myofibrillar myopathy histological changes. Conclusions: We report for the first time that hereditary myopathy with early respiratory failure patient can have peripheral nerve and severe spine involvement. The mutation in Ig-like domain 16 of FLNC is associated with the limb girdle type of filaminopathy, and the mutation in Ig-like domain 18 with distal myopathy type. These findings expand the phenotypic and genotypic correlation spectrum of myofibrillar myopathy.
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Affiliation(s)
- Yue-Bei Luo
- Department of Neurology, Xiangya Hospital, Central South Hospital, Changsha, China
| | - Yuyao Peng
- Department of Neurology, Xiangya Hospital, Central South Hospital, Changsha, China
| | - Yuling Lu
- Department of Neurology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Qiuxiang Li
- Department of Neurology, Xiangya Hospital, Central South Hospital, Changsha, China
| | - Huiqian Duan
- Department of Neurology, Xiangya Hospital, Central South Hospital, Changsha, China
| | - Fangfang Bi
- Department of Neurology, Xiangya Hospital, Central South Hospital, Changsha, China
| | - Huan Yang
- Department of Neurology, Xiangya Hospital, Central South Hospital, Changsha, China
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7
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Structure and Function of Filamin C in the Muscle Z-Disc. Int J Mol Sci 2020; 21:ijms21082696. [PMID: 32295012 PMCID: PMC7216277 DOI: 10.3390/ijms21082696] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/08/2020] [Accepted: 04/09/2020] [Indexed: 12/22/2022] Open
Abstract
Filamin C (FLNC) is one of three filamin proteins (Filamin A (FLNA), Filamin B (FLNB), and FLNC) that cross-link actin filaments and interact with numerous binding partners. FLNC consists of a N-terminal actin-binding domain followed by 24 immunoglobulin-like repeats with two intervening calpain-sensitive hinges separating R15 and R16 (hinge 1) and R23 and R24 (hinge-2). The FLNC subunit is dimerized through R24 and calpain cleaves off the dimerization domain to regulate mobility of the FLNC subunit. FLNC is localized in the Z-disc due to the unique insertion of 82 amino acid residues in repeat 20 and necessary for normal Z-disc formation that connect sarcomeres. Since phosphorylation of FLNC by PKC diminishes the calpain sensitivity, assembly, and disassembly of the Z-disc may be regulated by phosphorylation of FLNC. Mutations of FLNC result in cardiomyopathy and muscle weakness. Although this review will focus on the current understanding of FLNC structure and functions in muscle, we will also discuss other filamins because they share high sequence similarity and are better characterized. We will also discuss a possible role of FLNC as a mechanosensor during muscle contraction.
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8
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Verdonschot JAJ, Vanhoutte EK, Claes GRF, Helderman-van den Enden ATJM, Hoeijmakers JGJ, Hellebrekers DMEI, de Haan A, Christiaans I, Lekanne Deprez RH, Boen HM, van Craenenbroeck EM, Loeys BL, Hoedemaekers YM, Marcelis C, Kempers M, Brusse E, van Waning JI, Baas AF, Dooijes D, Asselbergs FW, Barge-Schaapveld DQCM, Koopman P, van den Wijngaard A, Heymans SRB, Krapels IPC, Brunner HG. A mutation update for the FLNC gene in myopathies and cardiomyopathies. Hum Mutat 2020; 41:1091-1111. [PMID: 32112656 PMCID: PMC7318287 DOI: 10.1002/humu.24004] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/12/2020] [Accepted: 02/25/2020] [Indexed: 12/11/2022]
Abstract
Filamin C (FLNC) variants are associated with cardiac and muscular phenotypes. Originally, FLNC variants were described in myofibrillar myopathy (MFM) patients. Later, high‐throughput screening in cardiomyopathy cohorts determined a prominent role for FLNC in isolated hypertrophic and dilated cardiomyopathies (HCM and DCM). FLNC variants are now among the more prevalent causes of genetic DCM. FLNC‐associated DCM is associated with a malignant clinical course and a high risk of sudden cardiac death. The clinical spectrum of FLNC suggests different pathomechanisms related to variant types and their location in the gene. The appropriate functioning of FLNC is crucial for structural integrity and cell signaling of the sarcomere. The secondary protein structure of FLNC is critical to ensure this function. Truncating variants with subsequent haploinsufficiency are associated with DCM and cardiac arrhythmias. Interference with the dimerization and folding of the protein leads to aggregate formation detrimental for muscle function, as found in HCM and MFM. Variants associated with HCM are predominantly missense variants, which cluster in the ROD2 domain. This domain is important for binding to the sarcomere and to ensure appropriate cell signaling. We here review FLNC genotype–phenotype correlations based on available evidence.
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Affiliation(s)
- Job A J Verdonschot
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands.,Department of Cardiology, Cardiovascular Research Institute (CARIM), Maastricht University Medical Center, Maastricht, The Netherlands
| | - Els K Vanhoutte
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Godelieve R F Claes
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | | | | | - Debby M E I Hellebrekers
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Amber de Haan
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Imke Christiaans
- Department of Clinical Genetics, Amsterdam University Medical Center, Amsterdam, The Netherlands.,Department of Clinical Genetics, University Medical Centre Groningen, Groningen, The Netherlands
| | - Ronald H Lekanne Deprez
- Department of Clinical Genetics, Amsterdam University Medical Center, Amsterdam, The Netherlands
| | - Hanne M Boen
- Department of Cardiology, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | | | - Bart L Loeys
- Department of Medical Genetics, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - Yvonne M Hoedemaekers
- Department of Clinical Genetics, University Medical Centre Groningen, Groningen, The Netherlands.,Department of Clinical Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Carlo Marcelis
- Department of Clinical Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Marlies Kempers
- Department of Clinical Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Esther Brusse
- Department of Neurology, Erasmus MC University Medical Centre, Rotterdam, The Netherlands
| | - Jaap I van Waning
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.,Department of Cardiology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Annette F Baas
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Dennis Dooijes
- Department of Genetics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Folkert W Asselbergs
- Department of Cardiology, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | - Arthur van den Wijngaard
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Stephane R B Heymans
- Department of Cardiology, Cardiovascular Research Institute (CARIM), Maastricht University Medical Center, Maastricht, The Netherlands.,Department of Cardiovascular Sciences, Centre for Molecular and Vascular Biology, KU Leuven, Leuven, Belgium.,The Netherlands Heart Institute, Utrecht, The Netherlands
| | - Ingrid P C Krapels
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Han G Brunner
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands.,Department of Clinical Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands.,Department of Genetics and Cell Biology, GROW Institute for Developmental Biology and Cancer, Maastricht University Medical Centre, Maastricht, The Netherlands
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9
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Lee HCH, Wong S, Sheng B, Pan NYK, Leung YKF, Lau KKD, Cheng YS, Ho LC, Li R, Lee CN, Tsoi TH, Cheung YFN, Fu YPM, Kan NCA, Chu YP, Au WCL, Yeung HMJ, Li SH, Cheung CFM, Tong HF, Hung LYE, Chan TYC, Li CT, Tong TYT, Tong TWC, Leung HYC, Lee KH, Yeung SYS, Lee SYB, Lau TCG, Lam CW, Mak CM, Chan AYW. Clinical and pathological characterization of FLNC-related myofibrillar myopathy caused by founder variant c.8129G>A in Hong Kong Chinese. Clin Genet 2020; 97:747-757. [PMID: 32022900 DOI: 10.1111/cge.13715] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 01/17/2020] [Accepted: 01/28/2020] [Indexed: 12/18/2022]
Abstract
FLNC-related myofibrillar myopathy could manifest as autosomal dominant late-onset slowly progressive proximal muscle weakness; involvements of cardiac and/or respiratory functions are common. We describe 34 patients in nine families of FLNC-related myofibrillar myopathy in Hong Kong ethnic Chinese diagnosed over the last 12 years, in whom the same pathogenic variant c.8129G>A (p.Trp2710*) was detected. Twenty-six patients were symptomatic when diagnosed; four patients died of pneumonia and/or respiratory failure. Abnormal amorphous material or granulofilamentous masses were detected in half of the cases, with mitochondrial abnormalities noted in two-thirds. We also show by haplotype analysis the founder effect associated with this Hong Kong variant, which might have occurred 42 to 71 generations ago or around Tang and Song dynasties, and underlain a higher incidence of myofibrillar myopathy among Hong Kong Chinese. The late-onset nature and slowly progressive course of the highly penetrant condition could have significant impact on the family members, and an early diagnosis could benefit the whole family. Considering another neighboring founder variant in FLNC in German patients, we advocate development of specific therapies such as chaperone-based or antisense oligonucleotide strategies for this particular type of myopathy.
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Affiliation(s)
| | - Shun Wong
- Department of Pathology, Princess Margaret Hospital, Hong Kong.,Pathology Department, St. Paul's Hospital, Hong Kong
| | - Bun Sheng
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong
| | - Nin-Yuan Keith Pan
- Department of Diagnostic Radiology, Princess Margaret Hospital, Hong Kong
| | | | | | - Yue Sandy Cheng
- Department of Clinical Pathology, Pamela Youde Nethersole Eastern Hospital, Hong Kong.,Department of Clinical Laboratory, Gleneagles Hong Kong Hospital, Hong Kong
| | - Luen-Cheung Ho
- Department of Pathology, Queen Elizabeth Hospital, Hong Kong
| | - Richard Li
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
| | - Chi-Nam Lee
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
| | - Tak-Hong Tsoi
- Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong
| | | | | | | | - Yim-Pui Chu
- Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong
| | - Wing-Chi Lisa Au
- Department of Medicine and Therapeutics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | | | - Siu-Hung Li
- Department of Medicine, North District Hospital, Hong Kong
| | | | - Hok-Fung Tong
- Department of Pathology, Princess Margaret Hospital, Hong Kong
| | | | | | - Chi Terence Li
- Department of Pathology, Princess Margaret Hospital, Hong Kong
| | | | | | | | - Ka-Ho Lee
- Department of Pathology, Princess Margaret Hospital, Hong Kong
| | | | | | | | - Ching-Wan Lam
- Department of Pathology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Chloe Miu Mak
- Department of Pathology, Princess Margaret Hospital, Hong Kong
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10
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Sveinbjornsson G, Olafsdottir EF, Thorolfsdottir RB, Davidsson OB, Helgadottir A, Jonasdottir A, Jonasdottir A, Bjornsson E, Jensson BO, Arnadottir GA, Kristinsdottir H, Stephensen SS, Oskarsson G, Gudbjartsson T, Sigurdsson EL, Andersen K, Danielsen R, Arnar DO, Jonsdottir I, Thorsteinsdottir U, Sulem P, Thorgeirsson G, Gudbjartsson DF, Holm H, Stefansson K. Variants in NKX2-5 and FLNC Cause Dilated Cardiomyopathy and Sudden Cardiac Death. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2019; 11:e002151. [PMID: 30354339 DOI: 10.1161/circgen.117.002151] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Dilated cardiomyopathy (DCM) is an important cause of heart failure. Variants in >50 genes have been reported to cause DCM, but causative variants have been found in less than half of familial cases. Variants causing DCM in Iceland have not been reported before. METHODS We performed a genome-wide association study on DCM based on whole genome sequencing. We tested the association of 32.5 million sequence variants in 424 cases and 337 689 population controls in Iceland. RESULTS We identified 2 DCM variants in established cardiomyopathy genes, a missense variant p.Phe145Leu in NKX2-5 carried by 1 in 7100 Icelanders ( P=7.0×10-12) and a frameshift variant p.Phe1626Serfs*40 in FLNC carried by 1 in 3600 Icelanders ( P=2.1×10-10). Both variants associate with heart failure and sudden cardiac death. Additionally, p.Phe145Leu in NKX2-5 associates with high degree atrioventricular block and atrial septal defect ( P<1.4×10-4). The penetrance of serious heart disease among carriers of the NKX2-5 variant is high and higher than that of the FLNC variant. CONCLUSIONS Two rare variants in NKX2-5 and FLNC, carried by 1 in 2400 Icelanders, cause familial DCM in Iceland. These genes have recently been associated with DCM. Given the serious consequences of these variants, we suggest screening for them in individuals with DCM and their family members, with subsequent monitoring of carriers, offering early intervention.
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Affiliation(s)
- Gardar Sveinbjornsson
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H.,School of Engineering and Natural Sciences (G.S., D.F.G.)
| | - Eva F Olafsdottir
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H.,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
| | | | - Olafur B Davidsson
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H
| | - Anna Helgadottir
- deCODE genetics/Amgen, Inc, Reykjavik, Iceland (G.S., E.F.O., R.B.T., O.B.D., A.H
| | | | | | - Eythor Bjornsson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
| | - Brynjar O Jensson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | - Gudny A Arnadottir
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | | | - Sigurdur S Stephensen
- Department of Pediatric Cardiology, Children's Hospital Reykjavik, Iceland (S.S.S., G.O.)
| | - Gylfi Oskarsson
- Department of Pediatric Cardiology, Children's Hospital Reykjavik, Iceland (S.S.S., G.O.)
| | - Tomas Gudbjartsson
- Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Cardiothoracic Surgery (T.G.)
| | - Emil L Sigurdsson
- Department of Family Medicine (E.L.S.), University of Iceland, Reykjavik.,Department of Development, Primary Health Care of the Capital Area, Reykjavik, Iceland (E.L.S.)
| | - Karl Andersen
- Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - Ragnar Danielsen
- Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - David O Arnar
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - Ingileif Jonsdottir
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Immunology, Landspitali, The National University Hospital of Iceland, Reykjavik (I.J.)
| | - Unnur Thorsteinsdottir
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
| | - Patrick Sulem
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | - Gudmundur Thorgeirsson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.).,Department of Medicine, Landspitali University Hospital, Reykjavik, Iceland (K.A., R.D., D.O.A., G.T.)
| | - Daniel F Gudbjartsson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,School of Engineering and Natural Sciences (G.S., D.F.G.)
| | - Hilma Holm
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.)
| | - Kari Stefansson
- Adalbjorg Jonasdottir, Aslaug Jonasdottir, E.B., B.O.J., G.A.A., D.O.A., I.J., U.T., P.S., G.T., D.F.G., H.H., K.S.).,Faculty of Medicine (E.F.O., E.B., H.K., T.G., K.A., D.O.A., I.J., U.T., G.T., K.S.)
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11
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A mutation in the filamin c gene causes myofibrillar myopathy with lower motor neuron syndrome: a case report. BMC Neurol 2019; 19:198. [PMID: 31421687 PMCID: PMC6697925 DOI: 10.1186/s12883-019-1410-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 07/23/2019] [Indexed: 11/13/2022] Open
Abstract
Background Myofibrillar myopathies (MFMs) are a genetically heterogeneous group of muscle disorders. Mutations in the filamin C gene (FLNC) have previously been identified in patients with MFM. The phenotypes of FLNC-related MFM are heterogeneous. Case presentation The patient was a 37-year-old male who first experienced weakness in the distal muscles of his hand, which eventually spread to the lower limbs and proximal muscles. Serum creatine kinase levels were moderately elevated. Obvious neuropathic changes in the electromyographic exam and edema changes in lower distal limb magnetic resonance imaging were observed. Histopathological examination revealed the presence of abnormal protein aggregates and angular atrophy in some muscle fibers. Ultrastructural analysis showed inordinate myofibrillar structures and dissolved myofilaments. DNA sequencing analysis detected a heterozygous missense mutation (c.7123G > A, p.V2375I) in the immunoglobulin (Ig)-like domain 21 of FLNC. Conclusions FLNC mutation c.7123G > A, p.V2375I in the immunoglobulin (Ig)-like domain 21 can be associated with distal myopathy with typical MFM features and lower motor neuron syndrome. Although electromyographic examination of our patient showed obvious neuropathic changes, MFM could not be excluded. Therefore, genetic testing is necessary to make an accurate diagnosis. Electronic supplementary material The online version of this article (10.1186/s12883-019-1410-7) contains supplementary material, which is available to authorized users.
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12
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Previtali SC, Scarlato M, Vezzulli P, Ruggieri A, Velardo D, Benedetti S, Torini G, Colombo B, Maggi L, Di Bella D, Gellera C, D'Angelo G, Mora M. Expanding the central nervous system disease spectrum associated with FLNC mutation. Muscle Nerve 2019; 59:E33-E37. [PMID: 30734317 DOI: 10.1002/mus.26443] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 11/05/2022]
Affiliation(s)
- Stefano C Previtali
- InSpe (Institute of Experimental Neurology), Division of Neuroscience and Dept. of Neurology, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Marina Scarlato
- InSpe (Institute of Experimental Neurology), Division of Neuroscience and Dept. of Neurology, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Paolo Vezzulli
- Neuroradiology Department, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Alessandra Ruggieri
- Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Daniele Velardo
- InSpe (Institute of Experimental Neurology), Division of Neuroscience and Dept. of Neurology, IRCCS Ospedale San Raffaele, Milano, Italy.,Neuromuscular Disorders Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Sara Benedetti
- Laboratory of Clinical Molecular Biology and Cytogenetics, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Giacomo Torini
- Genomic Unit for the Diagnosis of Human Pathologies, Division of Genetics and Cellular Biology, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Bruno Colombo
- InSpe (Institute of Experimental Neurology), Division of Neuroscience and Dept. of Neurology, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Lorenzo Maggi
- Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Daniela Di Bella
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Cinzia Gellera
- Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Grazia D'Angelo
- Neuromuscular Disorders Unit, Scientific Institute IRCCS E. Medea, Bosisio Parini, Lecco, Italy
| | - Marina Mora
- Neuromuscular Diseases and Neuroimmunology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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13
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Cui H, Wang J, Zhang C, Wu G, Zhu C, Tang B, Zou Y, Huang X, Hui R, Song L, Wang S. Mutation profile of FLNC gene and its prognostic relevance in patients with hypertrophic cardiomyopathy. Mol Genet Genomic Med 2018; 6:1104-1113. [PMID: 30411535 PMCID: PMC6305649 DOI: 10.1002/mgg3.488] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/30/2018] [Accepted: 09/14/2018] [Indexed: 01/18/2023] Open
Abstract
Background Filamin C (FLNC) mutation was reported as a cause of HCM, with a high probability of sudden cardiac death. However, the mutation profile of FLNC, and its relationship with phenotypic expression in HCM, remains to be elucidated. Methods In this study, FLNC gene was sequenced in 540 HCM patients and 307 healthy controls. Results We found that 39 (7.2%) patients carried FLNC mutations, with a similar frequency to that of controls (4.2%, p = 0.101). Pedigree analysis showed that mutations were not well segregated with HCM. The baseline characteristics between HCM patients, with and without mutations, were comparable. FLNC mutations did not increase the risk for either all‐cause mortality (HR 0.746, 95% CI 0.222–2.295, p = 0.575) or cardiac mortality (HR 0.615, 95% CI 0.153–1.947, p = 0.354) in HCM patients during a follow‐up of 4.7 ± 3.2 years. Moreover, there was no significant difference in survival free from sudden cardiac arrest (HR 0.721, 95% CI 0.128–3.667, p = 0.660) and heart failure (HR 0.757, 95% CI 0.318–1.642, p = 0.447). Conclusions FLNC mutations were common in both HCM patients and healthy population. The pathogenicity of FLNC mutations detected in HCM patients and its association with the clinical outcomes should be cautiously interpreted.
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Affiliation(s)
- Hao Cui
- Department of Cardiac Surgery, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jizheng Wang
- State Key Laboratory of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ce Zhang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Guixin Wu
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Changsheng Zhu
- Department of Cardiac Surgery, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Bing Tang
- Department of Cardiac Surgery, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yubao Zou
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiaohong Huang
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Rutai Hui
- State Key Laboratory of Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lei Song
- Department of Cardiology, Fuwai Hospital, National Center for Cardiovascular Disease, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Shuiyun Wang
- Department of Cardiac Surgery, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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14
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Schubert J, Tariq M, Geddes G, Kindel S, Miller EM, Ware SM. Novel pathogenic variants in filamin C identified in pediatric restrictive cardiomyopathy. Hum Mutat 2018; 39:2083-2096. [DOI: 10.1002/humu.23661] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 08/29/2018] [Accepted: 09/25/2018] [Indexed: 12/31/2022]
Affiliation(s)
- Jeffrey Schubert
- Department of Molecular Genetics, Microbiology, and Biochemistry; University of Cincinnati College of Medicine; Cincinnati Ohio
- Departments of Pediatrics and Medical and Molecular Genetics; Indiana University School of Medicine; Indianapolis Indiana
| | - Muhammad Tariq
- Faculty of Applied Medical Science; University of Tabuk; Tabuk Kingdom of Saudi Arabia
| | - Gabrielle Geddes
- Department of Pediatrics; Medical College of Wisconsin; Milwaukee Wisconsin
| | - Steven Kindel
- Department of Pediatrics; Medical College of Wisconsin; Milwaukee Wisconsin
| | - Erin M. Miller
- Cincinnati Children's Hospital Medical Center; Cincinnati Ohio
| | - Stephanie M. Ware
- Departments of Pediatrics and Medical and Molecular Genetics; Indiana University School of Medicine; Indianapolis Indiana
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15
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Kiselev A, Vaz R, Knyazeva A, Khudiakov A, Tarnovskaya S, Liu J, Sergushichev A, Kazakov S, Frishman D, Smolina N, Pervunina T, Jorholt J, Sjoberg G, Vershinina T, Rudenko D, Arner A, Sejersen T, Lindstrand A, Kostareva A. De novo mutations in FLNC
leading to early-onset restrictive cardiomyopathy and congenital myopathy. Hum Mutat 2018; 39:1161-1172. [DOI: 10.1002/humu.23559] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 11/09/2022]
Affiliation(s)
- Artem Kiselev
- Almazov National Medical Research Centre; Saint Petersburg Russia
| | - Raquel Vaz
- Department of Molecular Medicine and Surgery and Center for molecular medicine; Karolinska Institutet; Stockholm Sweden
| | | | | | - Svetlana Tarnovskaya
- Almazov National Medical Research Centre; Saint Petersburg Russia
- Peter the Great St.Petersburg Polytechnic University; Saint Petersburg Russia
| | - Jiao Liu
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
| | | | | | - Dmitrij Frishman
- Peter the Great St.Petersburg Polytechnic University; Saint Petersburg Russia
- Department of Bioinformatics; Technische Universität München; Wissenschaftszentrum Weihenstephan; Freising Germany
| | - Natalia Smolina
- Almazov National Medical Research Centre; Saint Petersburg Russia
- ITMO University; Saint Petersburg Russia
- Department of Women's and Children's Health and Center for Molecular Medicine; Karolinska Institute; Stockholm Sweden
| | | | - John Jorholt
- Department of Women's and Children's Health and Center for Molecular Medicine; Karolinska Institute; Stockholm Sweden
| | - Gunnar Sjoberg
- Department of Women's and Children's Health and Center for Molecular Medicine; Karolinska Institute; Stockholm Sweden
| | | | | | - Anders Arner
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
| | - Thomas Sejersen
- Department of Women's and Children's Health and Center for Molecular Medicine; Karolinska Institute; Stockholm Sweden
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery and Center for molecular medicine; Karolinska Institutet; Stockholm Sweden
- Clinical Genetics; Karolinska University Laboratory; Karolinska University Hospital; Stockholm Sweden
| | - Anna Kostareva
- Almazov National Medical Research Centre; Saint Petersburg Russia
- Department of Women's and Children's Health and Center for Molecular Medicine; Karolinska Institute; Stockholm Sweden
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16
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Miao J, Su FF, Liu XM, Wei XJ, Yuan Y, Yu XF. A case report: a heterozygous deletion (2791_2805 del) in exon 18 of the filamin C gene causing filamin C-related myofibrillar myopathies in a Chinese family. BMC Neurol 2018; 18:79. [PMID: 29866061 PMCID: PMC5985593 DOI: 10.1186/s12883-018-1078-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 05/22/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Filamin C-related myofibrillar myopathies (MFM) are progressive skeletal myopathies with an autosomal dominant inheritance pattern. The conditions are caused by mutations of the filamin C gene (FLNC) located in the chromosome 7q32-q35 region. Genetic variations in the FLNC gene result in various clinical phenotypes. CASE PRESENTATION We describe a 43-year-old woman who suffered filamin C-related MFM, with symptoms first presenting in the proximal muscles of the lower limbs and eventually spreading to the upper limbs and distal muscles. The patient's serum level of creatine kinase was mildly increased. Mildy myopathic changes in the electromyographic exam and moderate lipomatous alterations in lower limb MRI were found. Histopathological examination revealed increased muscle fiber size variability, disturbances in oxidative enzyme activity, and the presence of abnormal protein aggregates and vacuoles in some muscle fibers. Ultrastructural analysis showed inclusions composed of thin filaments and interspersed granular densities. DNA sequencing analysis detected a novel 15-nucleotide deletion (c.2791_2805del, p.931_935del) in the FLNC gene. The patient's father, sister, brother, three paternal aunts, one paternal uncle, and the uncle's son also had slowly progressive muscle weakness, and thus, we detected an autosomal dominant inheritance pattern of the disorder. CONCLUSIONS A novel heterogeneous 15-nucleotide deletion (c.2791_2805del, p.931_935del) in the Ig-like domain 7 of the FLNC gene was found to cause filamin C-related MFM. This deletion in the FLNC gene causes protein aggregation, abnormalities in muscle structure, and impairment in muscle fiber function, which leads to muscle weakness.
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Affiliation(s)
- Jing Miao
- Department of Neurology and Neuroscience Center, First Affiliated Hospital of Jilin University, Changchun, 130021 Jilin, People’s Republic of China
| | - Fei-fei Su
- Department of Neurology and Neuroscience Center, First Affiliated Hospital of Jilin University, Changchun, 130021 Jilin, People’s Republic of China
| | - Xue-mei Liu
- Department of Neurology and Neuroscience Center, First Affiliated Hospital of Jilin University, Changchun, 130021 Jilin, People’s Republic of China
| | - Xiao-jing Wei
- Department of Neurology and Neuroscience Center, First Affiliated Hospital of Jilin University, Changchun, 130021 Jilin, People’s Republic of China
| | - Yun Yuan
- Department of Neurology, Peking University First Hospital, #8 Xishiku St, Xicheng District, Beijing, 100034 China
| | - Xue-fan Yu
- Department of Neurology and Neuroscience Center First Affiliated Hospital of Jilin University, Changchun, 130021 Jilin, People’s Republic of China
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17
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Avila-Smirnow D, Gueneau L, Batonnet-Pichon S, Delort F, Bécane HM, Claeys K, Beuvin M, Goudeau B, Jais JP, Nelson I, Richard P, Ben Yaou R, Romero NB, Wahbi K, Mathis S, Voit T, Furst D, van der Ven P, Gil R, Vicart P, Fardeau M, Bonne G, Behin A. Cardiac arrhythmia and late-onset muscle weakness caused by a myofibrillar myopathy with unusual histopathological features due to a novel missense mutation in FLNC. Rev Neurol (Paris) 2016; 172:594-606. [PMID: 27633507 DOI: 10.1016/j.neurol.2016.07.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 07/16/2016] [Accepted: 07/26/2016] [Indexed: 11/29/2022]
Abstract
Myofibrillar myopathies (MFM) are mostly adult-onset diseases characterized by progressive morphological alterations of the muscle fibers beginning in the Z-disk and the presence of protein aggregates in the sarcoplasm. They are mostly caused by mutations in different genes that encode Z-disk proteins, including DES, CRYAB, LDB3, MYOT, FLNC and BAG3. A large family of French origin, presenting an autosomal dominant pattern, characterized by cardiac arrhythmia associated to late-onset muscle weakness, was evaluated to clarify clinical, morphological and genetic diagnosis. Muscle weakness began during adult life (over 30 years of age), and had a proximal distribution. Histology showed clear signs of a myofibrillar myopathy, but with unusual, large inclusions. Subsequently, genetic testing was performed in MFM genes available for screening at the time of clinical/histological diagnosis, and desmin (DES), αB-crystallin (CRYAB), myotilin (MYOT) and ZASP (LDB3), were excluded. LMNA gene screening found the p.R296C variant which did not co-segregate with the disease. Genome wide scan revealed linkage to 7q.32, containing the FLNC gene. FLNC direct sequencing revealed a heterozygous c.3646T>A p.Tyr1216Asn change, co-segregating with the disease, in a highly conserved amino acid of the protein. Normal filamin C levels were detected by Western-blot analysis in patient muscle biopsies and expression of the mutant protein in NIH3T3 showed filamin C aggregates. This is an original FLNC mutation in a MFM family with an atypical clinical and histopathological presentation, given the presence of significantly focal lesions and prominent sarcoplasmic masses in muscle biopsies and the constant heart involvement preceding significantly the onset of the myopathy. Though a rare etiology, FLNC gene should not be excluded in early-onset arrhythmia, even in the absence of myopathy, which occurs later in the disease course.
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Affiliation(s)
- D Avila-Smirnow
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France
| | - L Gueneau
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France
| | - S Batonnet-Pichon
- Sorbonne Paris Cité, université Paris Diderot, CNRS, unité de biologie fonctionnelle et adaptative, UMR 8251, 75013 Paris, France
| | - F Delort
- Sorbonne Paris Cité, université Paris Diderot, CNRS, unité de biologie fonctionnelle et adaptative, UMR 8251, 75013 Paris, France
| | - H-M Bécane
- AP-HP, groupe hospitalier Pitié-Salpêtrière, institut de myologie, centre de référence de pathologie neuromusculaire Paris-Est, 47-83, boulevard de l'Hôpital, 75013 Paris, France
| | - K Claeys
- Groupe hospitalier Pitié-Salpêtrière, association institut de myologie, unité de morphologie neuromusculaire, 75013 Paris, France
| | - M Beuvin
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France
| | - B Goudeau
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France
| | - J-P Jais
- GH Necker Enfants-Malades, université Paris Descartes, faculté de médecine, biostatistique et informatique médicale, EA 4067, 75015 Paris, France
| | - I Nelson
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France
| | - P Richard
- AP-HP, groupe hospitalier Pitié-Salpêtrière, service de biochimie métabolique, U.F. cardiogénétique et myogénétique, 75013 Paris, France
| | - R Ben Yaou
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France; AP-HP, groupe hospitalier Pitié-Salpêtrière, institut de myologie, centre de référence de pathologie neuromusculaire Paris-Est, 47-83, boulevard de l'Hôpital, 75013 Paris, France
| | - N B Romero
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France; Groupe hospitalier Pitié-Salpêtrière, association institut de myologie, unité de morphologie neuromusculaire, 75013 Paris, France
| | - K Wahbi
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France; AP-HP, groupe hospitalier Pitié-Salpêtrière, institut de myologie, centre de référence de pathologie neuromusculaire Paris-Est, 47-83, boulevard de l'Hôpital, 75013 Paris, France; AP-HP, groupe hospitalier Cochin-Broca-Hôtel Dieu, service de cardiologie, 75013 Paris, France
| | - S Mathis
- CHU de la Milétrie, service de neurologie, 86021 Poitiers, France
| | - T Voit
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France; AP-HP, groupe hospitalier Pitié-Salpêtrière, institut de myologie, centre de référence de pathologie neuromusculaire Paris-Est, 47-83, boulevard de l'Hôpital, 75013 Paris, France
| | - D Furst
- University of Bonn, institute for cell biology, department of molecular cell biology, Bonn, Germany
| | - P van der Ven
- University of Bonn, institute for cell biology, department of molecular cell biology, Bonn, Germany
| | - R Gil
- CHU de la Milétrie, service de neurologie, 86021 Poitiers, France
| | - P Vicart
- Sorbonne Paris Cité, université Paris Diderot, CNRS, unité de biologie fonctionnelle et adaptative, UMR 8251, 75013 Paris, France
| | - M Fardeau
- Groupe hospitalier Pitié-Salpêtrière, association institut de myologie, unité de morphologie neuromusculaire, 75013 Paris, France
| | - G Bonne
- Sorbonne universités, UPMC Paris 06, center of research in myology, Inserm UMRS974, CNRS FRE3617, 75013 Paris, France
| | - A Behin
- AP-HP, groupe hospitalier Pitié-Salpêtrière, institut de myologie, centre de référence de pathologie neuromusculaire Paris-Est, 47-83, boulevard de l'Hôpital, 75013 Paris, France.
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18
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Jiménez-Romero MS, Barcos-Martínez M, Espejo-Portero I, Benítez-Burraco A. Language Impairment Resulting from a de novo Deletion of 7q32.1q33. Mol Syndromol 2016; 7:292-298. [PMID: 27867345 DOI: 10.1159/000448208] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2016] [Indexed: 12/17/2022] Open
Abstract
We report on a girl who presents with hearing loss, behavioral disturbances (according to the Inventory for Client and Agency Planning) as well as motor and cognitive delay (according to Battelle Developmental Inventories) which have a significant impact on her speech and language abilities [according to the Peabody Picture Vocabulary Test (ed 3), and the Prueba de Lenguaje Oral de Navarra-Revisada (Navarra Oral Language Test, Revised)]. Five copy number variations (CNVs) were identified in the child: arr[hg18] 7q32.1q33(127109685-132492196)×1, 8p23.1(7156900-7359099) ×1, 15q13.1(26215673-26884937)×1, Xp22.33(17245- 102434)×3, and Xp22.33(964441-965024)×3. The pathogenicity of similar CNVs is mostly reported as unknown. The largest deletion is found in a hot spot for cognitive disease and language impairment and contains several genes involved in brain development and function, many of which have been related to developmental disorders encompassing language deficits (dyslexia, speech-sound disorder, and autism). Some of these genes interact with FOXP2. The proband's phenotype may result from a reduced expression of some of these genes.
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Affiliation(s)
- María S Jiménez-Romero
- Department of Psychology, University of Córdoba, Córdoba, Spain; Maimónides Institute of Biomedical Research, University Hospital 'Reina Sofía', Córdoba, Spain
| | - Montserrat Barcos-Martínez
- Maimónides Institute of Biomedical Research, University Hospital 'Reina Sofía', Córdoba, Spain; Laboratory of Molecular Genetics, University Hospital 'Reina Sofía', Córdoba, Spain
| | - Isabel Espejo-Portero
- Maimónides Institute of Biomedical Research, University Hospital 'Reina Sofía', Córdoba, Spain; Laboratory of Molecular Genetics, University Hospital 'Reina Sofía', Córdoba, Spain
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19
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Begay RL, Tharp CA, Martin A, Graw SL, Sinagra G, Miani D, Sweet ME, Slavov DB, Stafford N, Zeller MJ, Alnefaie R, Rowland TJ, Brun F, Jones KL, Gowan K, Mestroni L, Garrity DM, Taylor MRG. FLNC Gene Splice Mutations Cause Dilated Cardiomyopathy. JACC Basic Transl Sci 2016; 1:344-359. [PMID: 28008423 PMCID: PMC5166708 DOI: 10.1016/j.jacbts.2016.05.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A genetic etiology has been identified in 30% to 40% of dilated cardiomyopathy (DCM) patients, yet only 50% of these cases are associated with a known causative gene variant. Thus, in order to understand the pathophysiology of DCM, it is necessary to identify and characterize additional genes. In this study, whole exome sequencing in combination with segregation analysis was used to identify mutations in a novel gene, filamin C (FLNC), resulting in a cardiac-restricted DCM pathology. Here we provide functional data via zebrafish studies and protein analysis to support a model implicating FLNC haploinsufficiency as a mechanism of DCM. Deoxyribonucleic acid obtained from 2 large DCM families was studied using whole-exome sequencing and cosegregation analysis resulting in the identification of a novel disease gene, FLNC. The 2 families, from the same Italian region, harbored the same FLNC splice-site mutation (FLNC c.7251+1G>A). A third U.S. family was then identified with a novel FLNC splice-site mutation (FLNC c.5669-1delG) that leads to haploinsufficiency as shown by the FLNC Western blot analysis of the heart muscle. The FLNC ortholog flncb morpholino was injected into zebrafish embryos, and when flncb was knocked down caused a cardiac dysfunction phenotype. On electron microscopy, the flncb morpholino knockdown zebrafish heart showed defects within the Z-discs and sarcomere disorganization.
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Affiliation(s)
- Rene L Begay
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - Charles A Tharp
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - August Martin
- Center for Cardiovascular Research and Department of Biology, Colorado State University, Fort Collins, CO
| | - Sharon L Graw
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - Gianfranco Sinagra
- Cardiovascular Department, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Daniela Miani
- Department of Cardiothoracic Science, University Hospital S. Maria della Misericordia, Udine, Italy
| | - Mary E Sweet
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - Dobromir B Slavov
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - Neil Stafford
- Center for Cardiovascular Research and Department of Biology, Colorado State University, Fort Collins, CO; Cardiovascular and Biofluid Mechanics Laboratory, Colorado State University, Fort Collins, CO
| | - Molly J Zeller
- Center for Cardiovascular Research and Department of Biology, Colorado State University, Fort Collins, CO
| | - Rasha Alnefaie
- Center for Cardiovascular Research and Department of Biology, Colorado State University, Fort Collins, CO
| | - Teisha J Rowland
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - Francesca Brun
- Cardiovascular Department, Ospedali Riuniti and University of Trieste, Trieste, Italy
| | - Kenneth L Jones
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO
| | - Katherine Gowan
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver, Aurora, CO
| | - Luisa Mestroni
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
| | - Deborah M Garrity
- Center for Cardiovascular Research and Department of Biology, Colorado State University, Fort Collins, CO
| | - Matthew R G Taylor
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, Aurora, CO
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20
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Ruparelia AA, Oorschot V, Ramm G, Bryson-Richardson RJ. FLNC myofibrillar myopathy results from impaired autophagy and protein insufficiency. Hum Mol Genet 2016; 25:2131-2142. [PMID: 26969713 DOI: 10.1093/hmg/ddw080] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 03/07/2016] [Indexed: 01/23/2023] Open
Abstract
Myofibrillar myopathy is a progressive muscle disease characterized by the disintegration of muscle fibers and formation of protein aggregates. Causative mutations have been identified in nine genes encoding Z-disk proteins, including the actin binding protein filamin C (FLNC). To investigate the mechanism of disease in FLNCW2710X myopathy we overexpressed fluorescently tagged FLNC or FLNCW2710X in zebrafish. Expression of FLNCW2710X causes formation of protein aggregates but surprisingly, our studies reveal that the mutant protein localizes correctly to the Z-disk and is capable of rescuing the fiber disintegration phenotype that results from FLNC knockdown. This demonstrates that the functions necessary for muscle integrity are not impaired, and suggests that it is the formation of protein aggregates and subsequent sequestration of FLNC away from the Z-disk that results in myofibrillar disintegration. Similar to those found in patients, the aggregates in FLNCW2710X expressing fish contain the co-chaperone BAG3. FLNC is a target of the BAG3-mediated chaperone assisted selective autophagy (CASA) pathway and therefore we investigated its role, and the role of autophagy in general, in clearing protein aggregates. We reveal that despite BAG3 recruitment to the aggregates they are not degraded via CASA. Additionally, recruitment of BAG3 is sufficient to block alternative autophagy pathways which would otherwise clear the aggregates. This blockage can be relieved by reducing BAG3 levels or by stimulating autophagy. This study therefore identifies both BAG3 reduction and autophagy promotion as potential therapies for FLNCW2710X myofibrillar myopathy, and identifies protein insufficiency due to sequestration, compounded by impaired autophagy, as the cause.
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Affiliation(s)
| | - Viola Oorschot
- The Clive and Vera Ramaciotti Centre for Structural Cryo-Electron Microscopy and and
| | - Georg Ramm
- The Clive and Vera Ramaciotti Centre for Structural Cryo-Electron Microscopy and and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
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21
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Jackson S, Schaefer J, Meinhardt M, Reichmann H. Mitochondrial abnormalities in the myofibrillar myopathies. Eur J Neurol 2015. [DOI: 10.1111/ene.12814] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- S. Jackson
- Department of Neurology; Technische Universität Dresden; Dresden Germany
| | - J. Schaefer
- Department of Neurology; Technische Universität Dresden; Dresden Germany
| | - M. Meinhardt
- Department of Pathology; Technische Universität Dresden; Dresden Germany
| | - H. Reichmann
- Department of Neurology; Technische Universität Dresden; Dresden Germany
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22
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Abstract
PURPOSE OF REVIEW Myofibrillar myopathies (MFMs) are a heterogeneous group of skeletal and cardiac muscle diseases. In this review, we highlight recent discoveries of new genes and disease mechanisms involved in this group of disorders. RECENT FINDINGS The advent of next-generation sequencing technology, laser microdissection and mass spectrometry-based proteomics has facilitated the discovery of new MFM causative genes and pathomechanisms. New mutations have also been discovered in 'older' genes, helping to find a classification niche for MFM-linked disorders showing variant phenotypes. Cell transfection experiments using primary cultured myoblasts and newer animal models provide insights into the pathogenesis of MFMs. SUMMARY An increasing number of genes are involved in the causation of variant subtypes of MFM. The application of modern technologies in combination with classical histopathological and ultrastructural studies is helping to establish the molecular diagnosis and reach a better understanding of the pathogenic mechanisms of each MFM subtype, thus putting an emphasis on the development of specific means for prevention and therapy of these incapacitating and frequently fatal diseases.
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Toro C, Olivé M, Dalakas MC, Sivakumar K, Bilbao JM, Tyndel F, Vidal N, Farrero E, Sambuughin N, Goldfarb LG. Exome sequencing identifies titin mutations causing hereditary myopathy with early respiratory failure (HMERF) in families of diverse ethnic origins. BMC Neurol 2013; 13:29. [PMID: 23514108 PMCID: PMC3610280 DOI: 10.1186/1471-2377-13-29] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 03/08/2013] [Indexed: 01/12/2023] Open
Abstract
Background Hereditary myopathy with early respiratory failure (HMERF) was described in several North European families and recently linked to a titin gene (TTN) mutation. We independently studied HMERF-like diseases with the purpose to identify the cause, refine diagnostic criteria, and estimate the frequency of this disease among myopathy patients of various ethnic origins. Methods Whole exome sequencing analysis was carried out in a large U.S. family that included seven members suffering from skeletal muscle weakness and respiratory failure. Subsequent mutation screening was performed in further 45 unrelated probands with similar phenotypes. Studies included muscle strength evaluation, nerve conduction studies and concentric needle EMG, respiratory function test, cardiologic examination, and muscle biopsy. Results A novel TTN p.Gly30150Asp mutation was identified in the highly conserved A-band of titin that co-segregated with the disease in the U.S. family. Screening of 45 probands initially diagnosed as myofibrillar myopathy (MFM) but excluded based on molecular screening for the known MFM genes led to the identification of a previously reported TTN p.Cys30071Arg mutation in one patient. This same mutation was also identified in a patient with suspected HMERF. The p.Gly30150Asp and p.Cys30071Arg mutations are localized to a side chain of fibronectin type III element A150 of the 10th C-zone super-repeat of titin. Conclusions Missense mutations in TTN are the cause of HMERF in families of diverse origins. A comparison of phenotypic features of HMERF caused by the three known TTN mutations in various populations allowed to emphasize distinct clinical/pathological features that can serve as the basis for diagnosis. The newly identified p.Gly30150Asp and the p.Cys30071Arg mutation are localized to a side chain of fibronectin type III element A150 of the 10th C-zone super-repeat of titin.
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Affiliation(s)
- Camilo Toro
- Undiagnosed Diseases Program, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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24
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Fürst DO, Goldfarb LG, Kley RA, Vorgerd M, Olivé M, van der Ven PFM. Filamin C-related myopathies: pathology and mechanisms. Acta Neuropathol 2013; 125:33-46. [PMID: 23109048 DOI: 10.1007/s00401-012-1054-9] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 08/22/2012] [Accepted: 10/11/2012] [Indexed: 01/20/2023]
Abstract
The term filaminopathy was introduced after a truncating mutation in the dimerization domain of filamin C (FLNc) was shown to be responsible for a devastating muscle disease. Subsequently, the same mutation was found in patients from diverse ethnical origins, indicating that this specific alteration is a mutational hot spot. Patients initially present with proximal muscle weakness, while distal and respiratory muscles become affected with disease progression. Muscle biopsies of these patients show typical signs of myofibrillar myopathy, including disintegration of myofibrils and aggregation of several proteins into distinct intracellular deposits. Highly similar phenotypes were observed in patients with other mutations in Ig-like domains of FLNc that result in expression of a noxious protein. Biochemical and biophysical studies showed that the mutated domains acquire an abnormal structure causing decreased stability and eventually becoming a seed for abnormal aggregation with other proteins. The disease usually presents only after the fourth decade of life possibly as a result of ageing-related impairments in the machinery that is responsible for disposal of damaged proteins. This is confirmed by mutations in components of this machinery that cause a highly similar phenotype. Transfection studies of cultured muscle cells reflect the events observed in patient muscles and, therefore, may provide a helpful model for testing future dedicated therapeutic strategies. More recently, FLNC mutations were also found in families with a distal myopathy phenotype, caused either by mutations in the actin-binding domain of FLNc that result in increased actin-binding and non-specific myopathic abnormalities without myofibrillar myopathy pathology, or a nonsense mutation in the rod domain that leads to RNA instability, haploinsufficiency with decreased expression levels of FLNc in the muscle fibers and myofibrillar abnormalities, but not to the formation of desmin-positive protein aggregates required for the diagnosis of myofibrillar myopathy.
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Affiliation(s)
- Dieter O Fürst
- Institute for Cell Biology, University of Bonn, Ulrich-Haberland-Str. 61a, 53121 Bonn, Germany.
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