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Yavaş C, Doğan M, Eröz R, Türegün K. A rare TNNT1 gene variant causing creatine kinase elevation in nemaline myopathy: c.271_273del (p.Lys91del). Genes Genomics 2024; 46:613-620. [PMID: 38363456 DOI: 10.1007/s13258-024-01502-0] [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: 12/01/2023] [Accepted: 02/01/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND Nemaline Myopathy (NM) is a rare genetic disorder that affects muscle function and is characterized by the presence of nemaline rods in muscle fibers. These rods are abnormal structures that interfere with muscle contraction and can cause muscle weakness, respiratory distress, and other complications. NM is caused by variants in several genes, including TNNT1, which encodes the protein troponin T1. NM is inherited in an autosomal recessive pattern. The prevalence of heterozygous TNNT1 variants has been reported to be 1/152,000, indicating that the disease is relatively rare. OBJECTIVE Investigation of TNNT1 gene variants that may cause cretin kinase elevation. METHODS Detailed family histories and clinical data were recorded. Whole exome sequencing was performed and family segregation was done by Sanger sequencing. RESULTS In this study, we report a 5-year-old girl with a novel variant recessive congenital TNNT1 myopathy. The patient had a novel homozygous (c.271_273del) deletion in the TNNT1 gene that is associated with creatine kinase elevation, which is a marker of muscle damage. CONCLUSION This case expands the phenotypic spectrum of TNNT1 myopathy and highlights the importance of genetic testing and counseling for families affected by this rare disorder. In this study provides valuable insights into the genetic basis of NM and highlights the importance of early diagnosis and management for patients with this rare disorder. Further research is needed to better understand the pathophysiology of TNNT1 myopathy and to develop effective treatments for this debilitating condition.
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Affiliation(s)
- Cüneyd Yavaş
- Department of Molecular Biology and Genetics, Biruni University, Karanfil St. No:1H/12, Beylikduzu, Istanbul, 34100, Turkey.
| | - Mustafa Doğan
- Genetic Diseases Assessment Center, Basaksehir Cam and Sakura City Hospital, Istanbul, Turkey
| | - Recep Eröz
- Department of Medical Genetics Medical Faculty, Aksaray University, Aksaray, Turkey
| | - Kübra Türegün
- Department of Biotechnology, Institute of Science and Technology, Yıldız Technical University, Istanbul, Turkey
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Giriyappagoudar M, Vastrad B, Horakeri R, Vastrad C. Study on Potential Differentially Expressed Genes in Idiopathic Pulmonary Fibrosis by Bioinformatics and Next-Generation Sequencing Data Analysis. Biomedicines 2023; 11:3109. [PMID: 38137330 PMCID: PMC10740779 DOI: 10.3390/biomedicines11123109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 10/31/2023] [Accepted: 11/02/2023] [Indexed: 12/24/2023] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a chronic progressive lung disease with reduced quality of life and earlier mortality, but its pathogenesis and key genes are still unclear. In this investigation, bioinformatics was used to deeply analyze the pathogenesis of IPF and related key genes, so as to investigate the potential molecular pathogenesis of IPF and provide guidance for clinical treatment. Next-generation sequencing dataset GSE213001 was obtained from Gene Expression Omnibus (GEO), and the differentially expressed genes (DEGs) were identified between IPF and normal control group. The DEGs between IPF and normal control group were screened with the DESeq2 package of R language. The Gene Ontology (GO) and REACTOME pathway enrichment analyses of the DEGs were performed. Using the g:Profiler, the function and pathway enrichment analyses of DEGs were performed. Then, a protein-protein interaction (PPI) network was constructed via the Integrated Interactions Database (IID) database. Cytoscape with Network Analyzer was used to identify the hub genes. miRNet and NetworkAnalyst databaseswereused to construct the targeted microRNAs (miRNAs), transcription factors (TFs), and small drug molecules. Finally, receiver operating characteristic (ROC) curve analysis was used to validate the hub genes. A total of 958 DEGs were screened out in this study, including 479 up regulated genes and 479 down regulated genes. Most of the DEGs were significantly enriched in response to stimulus, GPCR ligand binding, microtubule-based process, and defective GALNT3 causes HFTC. In combination with the results of the PPI network, miRNA-hub gene regulatory network and TF-hub gene regulatory network, hub genes including LRRK2, BMI1, EBP, MNDA, KBTBD7, KRT15, OTX1, TEKT4, SPAG8, and EFHC2 were selected. Cyclothiazide and rotigotinethe are predicted small drug molecules for IPF treatment. Our findings will contribute to identification of potential biomarkers and novel strategies for the treatment of IPF, and provide a novel strategy for clinical therapy.
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Affiliation(s)
- Muttanagouda Giriyappagoudar
- Department of Radiation Oncology, Karnataka Institute of Medical Sciences (KIMS), Hubballi 580022, Karnataka, India;
| | - Basavaraj Vastrad
- Department of Pharmaceutical Chemistry, K.L.E. Socitey’s College of Pharmacy, Gadag 582101, Karnataka, India;
| | - Rajeshwari Horakeri
- Department of Computer Science, Govt First Grade College, Hubballi 580032, Karnataka, India;
| | - Chanabasayya Vastrad
- Biostatistics and Bioinformatics, Chanabasava Nilaya, Bharthinagar, Dharwad 580001, Karnataka, India
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Sorrentino U, Gabbiato I, Canciani C, Calosci D, Rigon C, Zuccarello D, Cassina M. Homozygous TNNI3 Mutations and Severe Early Onset Dilated Cardiomyopathy: Patient Report and Review of the Literature. Genes (Basel) 2023; 14:genes14030748. [PMID: 36981019 PMCID: PMC10048074 DOI: 10.3390/genes14030748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/14/2023] [Accepted: 03/16/2023] [Indexed: 03/22/2023] Open
Abstract
The TNNI3 gene encodes for the cardiac isoform of troponin I, a pivotal component of the sarcomeric structure of the myocardium. While heterozygous TNNI3 missense mutations have long been associated with autosomal dominant hypertrophic and restrictive cardiomyopathies, the role of TNNI3 null mutations has been more debated due to the paucity and weak characterization of reported cases and the low penetrance of heterozygous genotypes. In recent years, however, an increasing amount of evidence has validated the hypothesis that biallelic TNNI3 null mutations cause a severe form of neonatal dilated cardiomyopathy. Here, we expand the case series reporting two unrelated patients afflicted with early onset dilated cardiomyopathy, due to homozygosity for the p.Arg98* TNNI3 variant, which had thus far been documented only in heterozygous patients and apparently healthy carriers, and the recurrent p.Arg69Alafs*8 variant, respectively. A review of previously reported biallelic TNNI3 loss-of-function variants and their associated cardiac phenotypes was also performed.
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Affiliation(s)
- Ugo Sorrentino
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Ilaria Gabbiato
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Chiara Canciani
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Davide Calosci
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Chiara Rigon
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
| | - Daniela Zuccarello
- Clinical Genetics Unit, University Hospital of Padova, 35128 Padova, Italy
- Correspondence: ; Tel.: +39-0498212524
| | - Matteo Cassina
- Clinical Genetics Unit, Department of Women’s and Children’s Health, University of Padova, 35128 Padova, Italy; (U.S.); (I.G.); (C.C.); (D.C.); (C.R.); (M.C.)
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Christophers B, Lopez MA, Gupta VA, Vogel H, Baylies M. Pediatric Nemaline Myopathy: A Systematic Review Using Individual Patient Data. J Child Neurol 2022; 37:652-663. [PMID: 36960434 PMCID: PMC10032635 DOI: 10.1177/08830738221096316] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Nemaline myopathy is a skeletal muscle disease that affects 1 in 50 000 live births. The objective of this study was to develop a narrative synthesis of the findings of a systematic review of the latest case descriptions of patients with NM. A systematic search of MEDLINE, Embase, CINAHL, Web of Science, and Scopus was performed using Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using the keywords pediatric, child, NM, nemaline rod, and rod myopathy. Case studies focused on pediatric NM and published in English between January 1, 2010, and December 31, 2020, in order to represent the most recent findings. Information was collected about the age of first signs, earliest presenting neuromuscular signs and symptoms, systems affected, progression, death, pathologic description, and genetic changes. Of a total of 385 records, 55 case reports or series were reviewed, covering 101 pediatric patients from 23 countries. We review varying presentations in children ranging in severity despite being caused by the same mutation, in addition to current and future clinical considerations relevant to the care of patients with NM. This review synthesizes genetic, histopathologic, and disease presentation findings from pediatric NM case reports. These data strengthen our understanding of the wide spectrum of disease seen in NM. Future studies are needed to identify the underlying molecular mechanism of pathology, to improve diagnostics, and to develop better methods to improve the quality of life for these patients.
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Affiliation(s)
- Briana Christophers
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | | | - Vandana A. Gupta
- Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | | | - Mary Baylies
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
- Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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Holling T, Lisfeld J, Johannsen J, Matschke J, Song F, Altmeppen HC, Kutsche K. Autosomal dominantly inherited myopathy likely caused by the TNNT1 variant p.(Asp65Ala). Hum Mutat 2022; 43:1224-1233. [PMID: 35510366 DOI: 10.1002/humu.24397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 04/25/2022] [Accepted: 05/01/2022] [Indexed: 11/12/2022]
Abstract
Nemaline myopathies (NEM) are genetically and clinically heterogenous. Biallelic or monoallelic variants in TNNT1, encoding slow skeletal troponin T1 (TnT1), cause NEM. We report a 2-year-old patient and his mother carrying the heterozygous TNNT1 variant c.194A>C/p.(Asp65Ala) that occurred de novo in the mother. Both had muscle hypotrophy and muscle weakness. Muscle pathology in the proband's mother revealed slow twitch type 1 fiber hypotrophy and fast twitch type 2 fiber hypertrophy that was confirmed by a reduced ratio of slow skeletal myosin to fast skeletal myosin type 2a. RT-PCR and immunoblotting data demonstrated increased levels of high-molecular-weight TnT1 isoforms in skeletal muscle of the proband's mother that were also observed in some controls. In an overexpression system, complex formation of TnT1-D65A with tropomyosin 3 (TPM3) was enhanced. The previously reported TnT1-E104V and TnT1-L96P mutants showed reduced or no co-immunoprecipitation with TPM3. Our studies support pathogenicity of the TNNT1 p.(Asp65Ala) variant. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jasmin Lisfeld
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jessika Johannsen
- Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jakob Matschke
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Feizhi Song
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Zambon AA, Abel F, Linnane B, O'Rourke D, Phadke R, Sewry CA, Sarkozy A, Manzur A, Muntoni F. Troponin-T type 1 (TNNT1)-related nemaline myopathy: unique respiratory phenotype and muscle pathology findings. Neuromuscul Disord 2022; 32:245-254. [DOI: 10.1016/j.nmd.2022.01.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 01/26/2022] [Accepted: 01/27/2022] [Indexed: 10/19/2022]
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TNNT1 myopathy with novel compound heterozygous mutations. Neuromuscul Disord 2021; 32:176-184. [DOI: 10.1016/j.nmd.2021.12.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 12/07/2021] [Accepted: 12/10/2021] [Indexed: 01/10/2023]
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Laitila J, Wallgren-Pettersson C. Recent advances in nemaline myopathy. Neuromuscul Disord 2021; 31:955-967. [PMID: 34561123 DOI: 10.1016/j.nmd.2021.07.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 07/14/2021] [Accepted: 07/16/2021] [Indexed: 11/18/2022]
Abstract
The nemaline myopathies constitute a large proportion of the congenital or structural myopathies. Common to all patients is muscle weakness and the presence in the muscle biopsy of nemaline rods. The causative genes are at least twelve, encoding structural or regulatory proteins of the thin filament, and the clinical picture as well as the histological appearance on muscle biopsy vary widely. Here, we suggest a renewed clinical classification to replace the original one, summarise what is known about the pathogenesis from mutations in each causative gene to the forms of nemaline myopathy described to date, and provide perspectives on pathogenetic mechanisms possibly open to therapeutic modalities.
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Affiliation(s)
- Jenni Laitila
- The Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Finland; Department of Biomedical Sciences, University of Copenhagen, Denmark.
| | - Carina Wallgren-Pettersson
- The Folkhälsan Institute of Genetics, Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Finland
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Chen CP, Hsu CY, Chern SR, Wu PS, Chen SW, Wu FT, Wang W. Prenatal diagnosis of a 1.651-Mb 19q13.42-q13.43 microdeletion in a fetus with micrognathia and bilateral pyelectasis on prenatal ultrasound. Taiwan J Obstet Gynecol 2021; 59:763-765. [PMID: 32917333 DOI: 10.1016/j.tjog.2020.07.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2020] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE We present prenatal diagnosis of a de novo 1.651-Mb 19q13.42-q13.43 microdeletion in a fetus with micrognathia and bilateral pyelectasis on prenatal ultrasound. CASE REPORT A 32-year-old woman underwent amniocentesis at 28 weeks of gestation because of fetal micrognathia and bilateral pyelectasis on prenatal ultrasound. Amniocentesis revealed a karyotype of 46,XX. Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes revealed the result of arr 19q13.42q13.43 (55,028,722-56,680,564) × 1.0 [GRCh37 (hg19)] or a 1.651-Mb microdeletion encompassing 44 Online Mendelian Inheritance in Man (OMIM) genes including NLRP7, GP6, TNNT1, TNNI3 and DNAAF3. The parents did not have such a deletion and decided to continue the pregnancy. At 37 weeks of gestation, a 2560-g female baby was delivered by cesarean section because of oligohydramnios and decreased fetal movements. The baby manifested cleft palate, micrognathia and retrognathia at birth. She was doing well at age three months. Her body weight was 5.3 Kg (15th-25th centile), and body length was 59.2 cm (25th-50th centile). Renal sonogram showed bilateral mild pelvic dilation. She manifested no psychomotor retardation and no other internal organ abnormalities during pediatric follow-ups. CONCLUSION A 19q13.42-q13.43 microdeletion can be associated with micrognathia, retrognathia, cleft palate and bilateral pyelectasis at birth.
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Affiliation(s)
- Chih-Ping Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan; Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan; School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, Taiwan; Institute of Clinical and Community Health Nursing, National Yang-Ming University, Taipei, Taiwan; Department of Obstetrics and Gynecology, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
| | - Chin-Yuan Hsu
- Four Seasons Women and Children Clinics, Taipei, Taiwan
| | - Schu-Rern Chern
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
| | | | - Shin-Wen Chen
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Fang-Tzu Wu
- Department of Obstetrics and Gynecology, MacKay Memorial Hospital, Taipei, Taiwan
| | - Wayseen Wang
- Department of Medical Research, MacKay Memorial Hospital, Taipei, Taiwan
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Petrucci A, Primiano G, Savarese M, Sancricca C, Udd B, Servidei S. Novel TNNT1 mutation and mild nemaline myopathy phenotype in an Italian patient. Neuromuscul Disord 2021; 31:532-538. [PMID: 33832840 DOI: 10.1016/j.nmd.2021.03.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 02/15/2021] [Accepted: 03/01/2021] [Indexed: 12/19/2022]
Abstract
Mutations in the TNNT1 gene cause an infantile, lethal form of myopathy named "Amish" Nemaline Myopathy. Adult patients are very rarely described. We report a 49-year-old patient who presented a slowly progressive phenotype characterized by myalgia, exercise intolerance and dyspnea since infancy. In adult life she lapsed into a coma as a result of acute respiratory failure, with the need of tracheostomy, subsequently removed once her respiratory condition improved. Afterwards, non-invasive ventilation was started. Short stature, contractures, a small size posterior cranial fossa and osteonecrosis were additional clinical findings. Muscle MRI showed minor hypotrophy and degenerative changes of the muscles of the posterior thigh compartment and involvement of the paraspinal, medial gastrocnemius and soleus muscles with sparing of the gracilis muscle. Muscle biopsy revealed multiminicores and nemaline rods. Genetic analysis identified a new pathogenetic biallelic deletion c.786delG p.(Lys263Serfs*36) in exon 13 of TNNT1 gene. This case confirms that recessive mutations in TNNT1 gene can manifest mainly with respiratory failure in adult life.
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Affiliation(s)
- Antonio Petrucci
- Center for Neuromuscular and Neurological Rare Diseases, Neuroscience Department, San Camillo-Forlanini Hospital, Rome, Italy
| | - Guido Primiano
- UOC Neurofisiopatologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, Rome 00168, Italy; Dipartimento Universitario di Neuroscienze, Università Cattolica del Sacro Cuore, Roma, Italy.
| | - Marco Savarese
- Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland
| | - Cristina Sancricca
- UOC Neurofisiopatologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, Rome 00168, Italy; Dipartimento Universitario di Neuroscienze, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Bjarne Udd
- Folkhälsan Research Center, Helsinki, Finland; Department of Medical Genetics, Medicum, University of Helsinki, Helsinki, Finland; Neuromuscular Research Center, Tampere University and University Hospital, Tampere, Finland; Department of Neurology, Vaasa Central Hospital, Vaasa, Finland
| | - Serenella Servidei
- UOC Neurofisiopatologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Largo Agostino Gemelli 8, Rome 00168, Italy; Dipartimento Universitario di Neuroscienze, Università Cattolica del Sacro Cuore, Roma, Italy
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Clayton JS, McNamara EL, Goullee H, Conijn S, Muthsam K, Musk GC, Coote D, Kijas J, Testa AC, Taylor RL, O’Hara AJ, Groth D, Ottenheijm C, Ravenscroft G, Laing NG, Nowak KJ. Ovine congenital progressive muscular dystrophy (OCPMD) is a model of TNNT1 congenital myopathy. Acta Neuropathol Commun 2020; 8:142. [PMID: 32819427 PMCID: PMC7441672 DOI: 10.1186/s40478-020-01017-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/10/2020] [Indexed: 12/21/2022] Open
Abstract
Ovine congenital progressive muscular dystrophy (OCPMD) was first described in Merino sheep flocks in Queensland and Western Australia in the 1960s and 1970s. The most prominent feature of the disease is a distinctive gait with stiffness of the hind limbs that can be seen as early as 3 weeks after birth. The disease is progressive. Histopathological examination had revealed dystrophic changes specifically in type I (slow) myofibres, while electron microscopy had demonstrated abundant nemaline bodies. Therefore, it was never certain whether the disease was a dystrophy or a congenital myopathy with dystrophic features. In this study, we performed whole genome sequencing of OCPMD sheep and identified a single base deletion at the splice donor site (+ 1) of intron 13 in the type I myofibre-specific TNNT1 gene (KT218690 c.614 + 1delG). All affected sheep were homozygous for this variant. Examination of TNNT1 splicing by RT-PCR showed intron retention and premature termination, which disrupts the highly conserved 14 amino acid C-terminus. The variant did not reduce TNNT1 protein levels or affect its localization but impaired its ability to modulate muscle contraction in response to Ca2+ levels. Identification of the causative variant in TNNT1 finally clarifies that the OCPMD sheep is in fact a large animal model of TNNT1 congenital myopathy. This model could now be used for testing molecular or gene therapies.
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