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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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2
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Piñeros-Fernández MC, Morte B, García-Giménez JL. Utility of exome sequencing for the diagnosis of pediatric-onset neuromuscular diseases beyond diagnostic yield: a narrative review. Neurol Sci 2024; 45:1455-1464. [PMID: 37989827 PMCID: PMC10942921 DOI: 10.1007/s10072-023-07210-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 11/23/2023]
Abstract
Diagnosis of neuromuscular diseases (NMD) can be challenging because of the heterogeneity of this group of diseases. This review aimed to describe the diagnostic yield of whole exome sequencing (WES) for pediatric-onset neuromuscular disease diagnosis, as well as other benefits of this approach in patient management since WES can contribute to appropriate treatment selection in NMD patients. WES increases the possibility of reaching a conclusive genetic diagnosis when other technologies have failed and even exploring new genes not previously associated with a specific NMD. Moreover, this strategy can be useful when a dual diagnosis is suspected in complex congenital anomalies and undiagnosed cases.
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Affiliation(s)
- Martha Cecilia Piñeros-Fernández
- Servicio de Neurología Pediátrica, Hospital Pediátrico, Fundación Cardio Infantil-LaCardio, Bogotá, Colombia
- Unidad Pediátrica, Los Cobos Medical Center, Bogotá, Colombia
- Consulta Externa Especializada, Virrey Solís IPS, Bogotá, Colombia
| | - Beatriz Morte
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain
| | - José Luis García-Giménez
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain.
- Instituto de Investigación Sanitaria INCLIVA, Valencia, Spain.
- Departamento de Fisiología, Facultad de Medicina y Odontología, Universitat de València, València, Spain.
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Butler J, Dale N. X-linked Charcot Marie Tooth mutations alter CO 2 sensitivity of connexin32 hemichannels. Front Cell Neurosci 2023; 17:1330983. [PMID: 38188670 PMCID: PMC10771293 DOI: 10.3389/fncel.2023.1330983] [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: 10/31/2023] [Accepted: 12/07/2023] [Indexed: 01/09/2024] Open
Abstract
Connexin32 (Cx32) is expressed in myelinating Schwann cells. It forms both reflexive gap junctions, to facilitate transfer of molecules from the outer to the inner myelin layers and hemichannels at the paranode to permit action potential-evoked release of ATP into the extracellular space. Loss of function mutations in Cx32 cause X-linked Charcot Marie Tooth disease (CMTX), a slowly developing peripheral neuropathy. The mechanistic links between Cx32 mutations and CMTX are not well understood. As Cx32 hemichannels can be opened by increases in PCO2, we have examined whether CMTX mutations alter this CO2 sensitivity. By using Ca2+ imaging, dye loading and genetically encoded ATP sensors to measure ATP release, we have found 5 CMTX mutations that abolish the CO2 sensitivity of Cx32 hemichannels (A88D, 111-116 Del, C179Y, E102G, V139M). Others cause a partial loss (L56F, R220Stop, and R15W). Some CMTX mutations have no apparent effect on CO2 sensitivity (R15Q, L9F, G12S, V13L, V84I, W133R). The mutation R15W alters multiple additional aspects of hemichannel function including Ca2+ and ATP permeability. The mutations that abolish CO2 sensitivity are transdominant and abolish CO2 sensitivity of co-expressed Cx32WT. We have shown that Schwannoma RT4 D6P2T cells can release ATP in response to elevated PCO2 via the opening of Cx32. This is consistent with the hypothesis that the CO2 sensitivity of Cx32 may be important for maintenance of healthy myelin. Our data, showing a transdominant effect of certain CMTX mutations on CO2 sensitivity, may need to be taken into account in any future gene therapies for this condition.
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Affiliation(s)
| | - Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
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4
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Meyer AP, Ma J, Brock G, Hashimoto S, Cottrell CE, Mathew M, Hunter JM, Leung ML, Corsmeier D, Jayaraman V, Waldrop MA, Flanigan KM. Exome sequencing in the pediatric neuromuscular clinic leads to more frequent diagnosis of both neuromuscular and neurodevelopmental conditions. Muscle Nerve 2023; 68:833-840. [PMID: 37789688 DOI: 10.1002/mus.27976] [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: 01/06/2023] [Revised: 09/06/2023] [Accepted: 09/10/2023] [Indexed: 10/05/2023]
Abstract
INTRODUCTION/AIMS Exome sequencing (ES) has proven to be a valuable diagnostic tool for neuromuscular disorders, which often pose a diagnostic challenge. The aims of this study were to investigate the clinical outcomes associated with utilization of ES in the pediatric neuromuscular clinic and to determine if specific phenotypic features or abnormal neurodiagnostic tests were predictive of a diagnostic result. METHODS This was a retrospective medical record review of 76 pediatric neuromuscular clinic patients who underwent ES. Based upon clinical assessment prior to ES, patients were divided into two groups: affected by neuromuscular (n = 53) or non-neuromuscular (n = 23) syndromes. RESULTS A diagnosis was made in 28/76 (36.8%), with 29 unique disorders identified. In the neuromuscular group, a neuromuscular condition was confirmed in 78% of those receiving a genetic diagnosis. Early age of symptom onset was associated with a significantly higher diagnostic yield. The most common reason neuromuscular diagnoses were not detected on prior testing was due to causative genes not being present on disease-specific panels. Changes to medical care were made in 57% of individuals receiving a diagnosis on ES. DISCUSSION These data further support ES as a powerful diagnostic tool in the pediatric neuromuscular clinic and highlight the advantages of ES over gene panels, including the ability to identify diagnoses regardless of etiology, identify genes newly associated with disease, and identify multiple confounding diagnoses. Rapid and accurate diagnosis by ES can not only end the patient's diagnostic odyssey, but often impacts patients' medical management and genetic counseling of families.
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Affiliation(s)
- Alayne P Meyer
- Division of Genetic and Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Jianing Ma
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA
| | - Guy Brock
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, USA
| | - Sayaka Hashimoto
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Catherine E Cottrell
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Mariam Mathew
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Jesse M Hunter
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Marco L Leung
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pathology, The Ohio State University, Columbus, Ohio, USA
| | - Don Corsmeier
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Vijayakumar Jayaraman
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Megan A Waldrop
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- Department of Neurology, Nationwide Children's Hospital & The Ohio State University, Columbus, Ohio, USA
- Center for Gene Therapy, Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Kevin M Flanigan
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, Ohio, USA
- Department of Neurology, Nationwide Children's Hospital & The Ohio State University, Columbus, Ohio, USA
- Center for Gene Therapy, Nationwide Children's Hospital, Columbus, Ohio, USA
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5
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Akbar F, Saleem SM, Khalid E, Ibrahim S, Afroze B, Kirmani S, Khan S. The spectrum of hereditary neuromuscular disorders in the Pakistani population. Am J Med Genet A 2023; 191:2536-2550. [PMID: 37366078 DOI: 10.1002/ajmg.a.63332] [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: 03/02/2023] [Revised: 05/21/2023] [Accepted: 06/07/2023] [Indexed: 06/28/2023]
Abstract
Hereditary neuromuscular disorders (NMDs) are a broad group of clinically heterogeneous disorders with varying inheritance patterns, that are associated with over 500 implicated genes. In the context of a highly consanguineous Pakistani population, we expect that autosomal recessive NMDs may have a higher prevalence compared with patients of European descent. This is the first study to offer a detailed description of the spectrum of genes causing hereditary NMDs in the Pakistani population using NGS testing. To study the clinical and genetic profiles of patients presenting for evaluation of a hereditary neuromuscular disorder. This is a retrospective chart review of patients seen in the Neuromuscular Disorders Clinic and referred to the Genetics Clinic with a suspected hereditary neuromuscular disorder, between 2016 and 2020 at the Aga Khan University Hospital, Karachi and Mukhtiar A. Sheikh Hospital, Multan, Pakistan. The genetic testing for these patients included NGS-based single gene sequencing, NGS-based multi-gene panel and whole exome sequencing. In a total of 112 patients studied, 35 (31.3%) were female. The mean age of onset in all patients was 14.6 years (SD ±12.1 years), with the average age at presentation to the clinic of 22.4 years (SD ±14.10 years). Forty-seven (41.9%) patients had a positive genetic test result, 53 (47.3%) had one or more variants of uncertain significance (VUS), and 12 (10.7%) had a negative result. Upon further genotype-phenotype correlation and family segregation analysis, the diagnostic yield improved, with 59 (52.7%) patients reaching a diagnosis of a hereditary NMD. We also report probable founder variants in COL6A2, FKTN, GNE, and SGCB, previously reported in populations that have possible shared ancestry with the Pakistani population. Our findings reemphasizes that the rate of VUSs can be reduced by clinical correlation and family segregation studies.
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Affiliation(s)
- Fizza Akbar
- Division of Women and Child Health, The Aga Khan University, Karachi, Pakistan
| | | | | | - Shahnaz Ibrahim
- Department of Paediatrics and Child Health, The Aga Khan University, Karachi, Pakistan
| | - Bushra Afroze
- Department of Paediatrics and Child Health, The Aga Khan University, Karachi, Pakistan
| | - Salman Kirmani
- Division of Women and Child Health, The Aga Khan University, Karachi, Pakistan
| | - Sara Khan
- Department of Neurology, The Aga Khan University, Karachi, Pakistan
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6
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Mianesaz H, Ghalamkari S, Salehi M, Behnam M, Hosseinzadeh M, Basiri K, Ghasemi M, Sedghi M, Ansari B. Causative variants linked with limb girdle muscular dystrophy in an Iranian population: 6 novel variants. Mol Genet Genomic Med 2022; 11:e2101. [PMID: 36374152 PMCID: PMC9938754 DOI: 10.1002/mgg3.2101] [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: 06/12/2022] [Revised: 10/03/2022] [Accepted: 11/03/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Limb-girdle muscular dystrophy (LGMD) is a non-syndromic muscular dystrophy caused by variations in the genes involved in muscle structure, function and repair. The heterogeneity in the severity, progression, age of onset, and causative genes makes next-generation sequencing (NGS) a necessary approach for the proper diagnosis of LGMD. METHODS In this article, 26 Iranian patients with LGMD criteria were diagnosed with disease variants in the genes encoding calpain3, dysferlin, sarcoglycans and Laminin α-2. Patients were referred to the hospital with variable distribution of muscle wasting and progressive weakness in the body. The symptoms along with biochemical and EMG tests were suggestive of LGMD; thus the genomic DNA of patients were investigated by whole-exome sequencing including flanking intronic regions. The target genes were explored for the disease-causing variants. Moreover, the consequence of the amino acid alterations on proteins' secondary structure and function was investigated for a better understanding of the pathogenicity of variants. Variants were sorted based on the genomic region, type and clinical significance. RESULTS In a comprehensive investigation of previous clinical records, 6 variations were determined as novel, including c.1354-2 A > T and c.3169_3172dupCGGC in DYSF, c.568 G > T in SGCD, c.7243 C > T, c.8662_8663 insT and c. 4397G > C in LAMA2. Some of the detected variants were located in functional domains and/or near to the post-translational modification sites, altering or removing highly conserved regions of amino acid sequence.
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Affiliation(s)
- Hamidreza Mianesaz
- Department of Human Genetics, Medical SchoolUniversity of DebrecenDebrecenHungary,Department of Genetics and Molecular BiologyIsfahan University of Medical SciencesIsfahanIran
| | - Safoura Ghalamkari
- Department of Genetics and Molecular BiologyIsfahan University of Medical SciencesIsfahanIran,Division of Clinical Genetics, Department of Laboratory Medicine, Faculty of MedicineUniversity of DebrecenDebrecenHungary
| | - Mansoor Salehi
- Department of Genetics and Molecular BiologyIsfahan University of Medical SciencesIsfahanIran,Cellular, Molecular and Genetics Research CenterIsfahan University of Medical SciencesIsfahanIran
| | - Mahdiyeh Behnam
- Cellular, Molecular and Genetics Research CenterIsfahan University of Medical SciencesIsfahanIran,Student Research CommitteeSemnan University of Medical ScienceSemnanIran
| | - Majid Hosseinzadeh
- Department of Genetics and Molecular BiologyIsfahan University of Medical SciencesIsfahanIran,Medical Genetics Laboratory, Alzahra University HospitalIsfahan University of Medical SciencesIsfahanIran
| | - Keivan Basiri
- Metabolic Disorders Research Center, Endocrinology and Metabolism Molecular‐Cellular Sciences InstituteTehran University of Medical ScienceTehranIran,Department of NeurologyIsfahan University of Medical SciencesIsfahanIran
| | - Majid Ghasemi
- Metabolic Disorders Research Center, Endocrinology and Metabolism Molecular‐Cellular Sciences InstituteTehran University of Medical ScienceTehranIran,Department of NeurologyIsfahan University of Medical SciencesIsfahanIran
| | - Maryam Sedghi
- Medical Genetics Laboratory, Alzahra University HospitalIsfahan University of Medical SciencesIsfahanIran,Metabolic Disorders Research Center, Endocrinology and Metabolism Molecular‐Cellular Sciences InstituteTehran University of Medical ScienceTehranIran
| | - Behnaz Ansari
- Department of NeurologyIsfahan University of Medical SciencesIsfahanIran,Isfahan Neuroscience Research Center, ALzahra Research InstituteIsfahan University of Medical ScienceIsfahanIran
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Whole exome sequencing identified a novel LAMA2 frameshift variant causing merosin-deficient congenital muscular dystrophy in a patient with cardiomyopathy, and autism-like behaviors. Neuromuscul Disord 2022; 32:776-784. [DOI: 10.1016/j.nmd.2022.07.400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 07/06/2022] [Accepted: 07/20/2022] [Indexed: 11/21/2022]
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8
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Yunisova G, Ceylaner S, Oflazer P, Deymeer F, Parman YG, Durmus H. Clinical and genetic characteristics of Emery-Dreifuss muscular dystrophy patients from Turkey: 30 years longitudinal follow-up study. Neuromuscul Disord 2022; 32:718-727. [DOI: 10.1016/j.nmd.2022.07.397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 06/29/2022] [Accepted: 07/11/2022] [Indexed: 10/17/2022]
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9
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Masri AT, Oweis L, Qudah AA, El-Shanti H. Congenital muscle dystrophies: Role of singleton whole exome sequencing in countries with limited resources. Clin Neurol Neurosurg 2022; 217:107271. [DOI: 10.1016/j.clineuro.2022.107271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/24/2022] [Accepted: 04/25/2022] [Indexed: 12/01/2022]
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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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11
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Narayanaswami P, Živković S. Molecular and Genetic Therapies. Neuromuscul Disord 2022. [DOI: 10.1016/b978-0-323-71317-7.00011-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Khorrami A, Goleij P, Karamad V, Taheri E, Shadman B, Emami P, Jahangirzadeh G, Hajazimian S, Isazadeh A, Baradaran B, Heidari M. Identification of a compound heterozygous missense mutation in LAMA2 gene from a patient with merosin-deficient congenital muscular dystrophy type 1A. J Clin Lab Anal 2021; 35:e23930. [PMID: 34528292 PMCID: PMC8605159 DOI: 10.1002/jcla.23930] [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: 05/06/2021] [Revised: 06/29/2021] [Accepted: 07/20/2021] [Indexed: 01/08/2023] Open
Abstract
Background Merosin‐deficient congenital muscular dystrophy type 1A (MDC1A) is occurred by mutations in LAMA2 gene that encodes the laminin α2 chain (merosin). MDC1A is a predominant subtype of congenital muscular dystrophy. Herein, we identified two missense mutations in LAMA2 gene in compound heterozygous status in an Iranian patient with MDC1A using whole‐exome sequencing (WES). Methods In the present study, we evaluated genetic alterations in an Iranian 35‐month‐old boy with MDC1A and his healthy family using WES method. The identified mutations further confirmed by Sanger sequencing method. Finally, in silico analysis was conducted to further evaluation of molecular function of the identified genetic variants. Results We identified two potentially pathogenic missense mutations in compound heterozygous state (c.7681G>A p.Gly2561Ser and c.4840A>G p.Asn1614Asp) in LAMA2 gene as contributing to the MDC1A phenotype. The healthy parents of our proband are single heterozygous for identified mutations. These variants were found to be pathogenic by in silico analysis. Conclusions In general, we successfully identified LAMA2 gene mutations in an Iranian patient with MDC1A using WES. The identified mutations in LAMA2 gene can be useful in genetic counseling, prenatal diagnosis, and predicting prognosis of MDC1A.
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Affiliation(s)
- Afshin Khorrami
- Young Researchers and Elit Club, Varamin-Pishva Branch, Islamic Azad University, Varamin-Pishva, Iran
| | - Pouya Goleij
- Department of Genetics, Faculty of Biology, Sana Institute of Higher Education, Sari, Iran
| | - Vahidreza Karamad
- Department of Medical Biology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - Elham Taheri
- Department of Pharmaceutical Biotechnology, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behrouz Shadman
- Department of Medical Biology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - Parisa Emami
- Department of Genetics, Ahar Branch, Islamic Azad University, Ahar, Iran
| | | | - Saba Hajazimian
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Alireza Isazadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behzad Baradaran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mansour Heidari
- Department of Medical Genetics, Tehran University of Medical Sciences (TUMS), Tehran, Iran
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van de Locht M, Borsboom TC, Winter JM, Ottenheijm CAC. Troponin Variants in Congenital Myopathies: How They Affect Skeletal Muscle Mechanics. Int J Mol Sci 2021; 22:ijms22179187. [PMID: 34502093 PMCID: PMC8430961 DOI: 10.3390/ijms22179187] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 02/05/2023] Open
Abstract
The troponin complex is a key regulator of muscle contraction. Multiple variants in skeletal troponin encoding genes result in congenital myopathies. TNNC2 has been implicated in a novel congenital myopathy, TNNI2 and TNNT3 in distal arthrogryposis (DA), and TNNT1 and TNNT3 in nemaline myopathy (NEM). Variants in skeletal troponin encoding genes compromise sarcomere function, e.g., by altering the Ca2+ sensitivity of force or by inducing atrophy. Several potential therapeutic strategies are available to counter the effects of variants, such as troponin activators, introduction of wild-type protein through AAV gene therapy, and myosin modulation to improve muscle contraction. The mechanisms underlying the pathophysiological effects of the variants in skeletal troponin encoding genes are incompletely understood. Furthermore, limited knowledge is available on the structure of skeletal troponin. This review focusses on the physiology of slow and fast skeletal troponin and the pathophysiology of reported variants in skeletal troponin encoding genes. A better understanding of the pathophysiological effects of these variants, together with enhanced knowledge regarding the structure of slow and fast skeletal troponin, will direct the development of treatment strategies.
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14
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Nicolau S, Milone M, Liewluck T. Guidelines for genetic testing of muscle and neuromuscular junction disorders. Muscle Nerve 2021; 64:255-269. [PMID: 34133031 DOI: 10.1002/mus.27337] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 12/24/2022]
Abstract
Despite recent advances in the understanding of inherited muscle and neuromuscular junction diseases, as well as the advent of a wide range of genetic tests, patients continue to face delays in diagnosis of sometimes treatable disorders. These guidelines outline an approach to genetic testing in such disorders. Initially, a patient's phenotype is evaluated to identify myopathies requiring directed testing, including myotonic dystrophies, facioscapulohumeral muscular dystrophy, oculopharyngeal muscular dystrophy, mitochondrial myopathies, dystrophinopathies, and oculopharyngodistal myopathy. Initial investigation in the remaining patients is generally a comprehensive gene panel by next-generation sequencing. Broad panels have a higher diagnostic yield and can be cost-effective. Due to extensive phenotypic overlap and treatment implications, genes responsible for congenital myasthenic syndromes should be included when evaluating myopathy patients. For patients whose initial genetic testing is negative or inconclusive, phenotypic re-evaluation is warranted, along with consideration of genes and variants not included initially, as well as their acquired mimickers.
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Affiliation(s)
- Stefan Nicolau
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Teerin Liewluck
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
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El Kadiri Y, Ratbi I, Laarabi FZ, Kriouile Y, Sefiani A, Lyahyai J. Identification of a novel LAMA2 c.2217G > A, p.(Trp739*) mutation in a Moroccan patient with congenital muscular dystrophy: a case report. BMC Med Genomics 2021; 14:113. [PMID: 33882917 PMCID: PMC8060993 DOI: 10.1186/s12920-021-00959-2] [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: 02/06/2021] [Accepted: 04/12/2021] [Indexed: 01/22/2023] Open
Abstract
Background Merosin-deficient congenital muscular dystrophy type 1A (MDC1A) is a rare autosomal recessive genetic condition caused by deleterious mutations in the LAMA2 gene encoding the laminin-α2 chain. It is the most frequent subtype of congenital muscular dystrophies (CMDs) characterized by total laminin-α2 deficiency with muscle weakness at birth or in the first six months of life. To the best of our knowledge, this study reports the first molecular diagnosis and genetic defect of this heterogeneous form of CMD performed in a Moroccan medical genetic center using next-generation sequencing (NGS). It allows us to expand the mutational spectrum of the LAMA2 gene. Case presentation We report the case of a female Moroccan child with clinical and paraclinical features in favor of a CMD. She has global congenital hypotonia with generalized muscle weakness, psychomotor retardation, increased serum creatine kinase, and normal brain scan at the age of six months. Targeted NGS leads to the identification of a novel homozygous nonsense mutation c.2217G > A, p.(Trp739*) in the exon 16 of LAMA2. Sanger sequencing confirmed this mutation in the affected patient and showed that her parents are heterozygous carriers. Conclusions A modern genetic analysis by NGS improves the genetic diagnosis pathway for adequate genetic counseling of affected families more precisely. An accession number from the National Center for Biotechnology Information (NCBI) ClinVar database was retrieved for this novel LAMA2 mutation.
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Affiliation(s)
- Youssef El Kadiri
- Centre de Recherche en Génomique des Pathologies Humaines (GENOPATH), Faculté de Médecine et de Pharmacie, Mohammed V University in Rabat, 10100, Rabat, Morocco. .,Département de Génétique Médicale, Institut National d'Hygiène, BP 769 Agdal, 10090, Rabat, Morocco.
| | - Ilham Ratbi
- Centre de Recherche en Génomique des Pathologies Humaines (GENOPATH), Faculté de Médecine et de Pharmacie, Mohammed V University in Rabat, 10100, Rabat, Morocco
| | - Fatima Zahra Laarabi
- Département de Génétique Médicale, Institut National d'Hygiène, BP 769 Agdal, 10090, Rabat, Morocco
| | - Yamna Kriouile
- Unité de Neuropédiatrie et Maladies Neuro-Métaboliques, Service de Pédiatrie 2- Hôpital d'enfants, Rabat, Morocco
| | - Abdelaziz Sefiani
- Centre de Recherche en Génomique des Pathologies Humaines (GENOPATH), Faculté de Médecine et de Pharmacie, Mohammed V University in Rabat, 10100, Rabat, Morocco.,Département de Génétique Médicale, Institut National d'Hygiène, BP 769 Agdal, 10090, Rabat, Morocco
| | - Jaber Lyahyai
- Centre de Recherche en Génomique des Pathologies Humaines (GENOPATH), Faculté de Médecine et de Pharmacie, Mohammed V University in Rabat, 10100, Rabat, Morocco
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16
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Yubero D, Natera-de Benito D, Pijuan J, Armstrong J, Martorell L, Fernàndez G, Maynou J, Jou C, Roldan M, Ortez C, Nascimento A, Hoenicka J, Palau F. The Increasing Impact of Translational Research in the Molecular Diagnostics of Neuromuscular Diseases. Int J Mol Sci 2021; 22:4274. [PMID: 33924139 PMCID: PMC8074304 DOI: 10.3390/ijms22084274] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/13/2021] [Accepted: 04/16/2021] [Indexed: 12/12/2022] Open
Abstract
The diagnosis of neuromuscular diseases (NMDs) has been progressively evolving from the grouping of clinical symptoms and signs towards the molecular definition. Optimal clinical, biochemical, electrophysiological, electrophysiological, and histopathological characterization is very helpful to achieve molecular diagnosis, which is essential for establishing prognosis, treatment and genetic counselling. Currently, the genetic approach includes both the gene-targeted analysis in specific clinically recognizable diseases, as well as genomic analysis based on next-generation sequencing, analyzing either the clinical exome/genome or the whole exome or genome. However, as of today, there are still many patients in whom the causative genetic variant cannot be definitely established and variants of uncertain significance are often found. In this review, we address these drawbacks by incorporating two additional biological omics approaches into the molecular diagnostic process of NMDs. First, functional genomics by introducing experimental cell and molecular biology to analyze and validate the variant for its biological effect in an in-house translational diagnostic program, and second, incorporating a multi-omics approach including RNA-seq, metabolomics, and proteomics in the molecular diagnosis of neuromuscular disease. Both translational diagnostics programs and omics are being implemented as part of the diagnostic process in academic centers and referral hospitals and, therefore, an increase in the proportion of neuromuscular patients with a molecular diagnosis is expected. This improvement in the process and diagnostic performance of patients will allow solving aspects of their health problems in a precise way and will allow them and their families to take a step forward in their lives.
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Affiliation(s)
- Dèlia Yubero
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
| | - Daniel Natera-de Benito
- Neuromuscular Unit, Department of Pediatric Neurology, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.N.-d.B.); (C.O.)
| | - Jordi Pijuan
- Laboratory of Neurogenetics and Molecular Medicine—IPER, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain;
| | - Judith Armstrong
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
| | - Loreto Martorell
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Laboratory of Neurogenetics and Molecular Medicine—IPER, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain;
| | - Guerau Fernàndez
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
| | - Joan Maynou
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
| | - Cristina Jou
- Department of Pathology, Hospital Sant Joan de Déu, Pediatric Biobank for Research, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain;
| | - Mònica Roldan
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Confocal Microscopy and Cellular Imaging Unit, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain
| | - Carlos Ortez
- Neuromuscular Unit, Department of Pediatric Neurology, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.N.-d.B.); (C.O.)
- Division of Pediatrics, Clinic Institute of Medicine & Dermatology, Hospital Clínic, University of Barcelona School of Medicine and Health Sciences, 08950 Barcelona, Spain
| | - Andrés Nascimento
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
- Neuromuscular Unit, Department of Pediatric Neurology, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.N.-d.B.); (C.O.)
| | - Janet Hoenicka
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
- Laboratory of Neurogenetics and Molecular Medicine—IPER, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain;
| | - Francesc Palau
- Department of Genetic and Molecular Medicine—IPER, Hospital Sant Joan de Déu and Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain; (D.Y.); (J.A.); (L.M.); (G.F.); (J.M.); (M.R.)
- Center for Biomedical Research Network on Rare Diseases (CIBERER), ISCIII, 08950 Barcelona, Spain;
- Laboratory of Neurogenetics and Molecular Medicine—IPER, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain;
- Department of Pathology, Hospital Sant Joan de Déu, Pediatric Biobank for Research, Institut de Recerca Sant Joan de Déu, 08950 Barcelona, Spain;
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17
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Barp A, Mosca L, Sansone VA. Facilitations and Hurdles of Genetic Testing in Neuromuscular Disorders. Diagnostics (Basel) 2021; 11:diagnostics11040701. [PMID: 33919863 PMCID: PMC8070835 DOI: 10.3390/diagnostics11040701] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/11/2021] [Accepted: 04/12/2021] [Indexed: 12/11/2022] Open
Abstract
Neuromuscular disorders (NMDs) comprise a heterogeneous group of disorders that affect about one in every thousand individuals worldwide. The vast majority of NMDs has a genetic cause, with about 600 genes already identified. Application of genetic testing in NMDs can be useful for several reasons: correct diagnostic definition of a proband, extensive familial counselling to identify subjects at risk, and prenatal diagnosis to prevent the recurrence of the disease; furthermore, identification of specific genetic mutations still remains mandatory in some cases for clinical trial enrollment where new gene therapies are now approaching. Even though genetic analysis is catching on in the neuromuscular field, pitfalls and hurdles still remain and they should be taken into account by clinicians, as for example the use of next generation sequencing (NGS) where many single nucleotide variants of “unknown significance” can emerge, complicating the correct interpretation of genotype-phenotype relationship. Finally, when all efforts in terms of molecular analysis have been carried on, a portion of patients affected by NMDs still remain “not genetically defined”. In the present review we analyze the evolution of genetic techniques, from Sanger sequencing to NGS, and we discuss “facilitations and hurdles” of genetic testing which must always be balanced by clinicians, in order to ensure a correct diagnostic definition, but taking always into account the benefit that the patient could obtain especially in terms of “therapeutic offer”.
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Affiliation(s)
- Andrea Barp
- The NEMO Clinical Center in Milan, Neurorehabilitation Unit, University of Milan, Piazza Ospedale Maggiore 3, 20162 Milano, Italy;
- Correspondence:
| | - Lorena Mosca
- Medical Genetics Unit, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore 3, 20162 Milano, Italy;
| | - Valeria Ada Sansone
- The NEMO Clinical Center in Milan, Neurorehabilitation Unit, University of Milan, Piazza Ospedale Maggiore 3, 20162 Milano, Italy;
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18
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Abstract
Neuromuscular disorders (NMDs) comprise a heterogeneous group of disorders that affect about one in every thousand individuals worldwide. The vast majority of NMDs has a genetic cause, with about 600 genes already identified. Application of genetic testing in NMDs can be useful for several reasons: correct diagnostic definition of a proband, extensive familial counselling to identify subjects at risk, and prenatal diagnosis to prevent the recurrence of the disease; furthermore, identification of specific genetic mutations still remains mandatory in some cases for clinical trial enrollment where new gene therapies are now approaching. Even though genetic analysis is catching on in the neuromuscular field, pitfalls and hurdles still remain and they should be taken into account by clinicians, as for example the use of next generation sequencing (NGS) where many single nucleotide variants of "unknown significance" can emerge, complicating the correct interpretation of genotype-phenotype relationship. Finally, when all efforts in terms of molecular analysis have been carried on, a portion of patients affected by NMDs still remain "not genetically defined". In the present review we analyze the evolution of genetic techniques, from Sanger sequencing to NGS, and we discuss "facilitations and hurdles" of genetic testing which must always be balanced by clinicians, in order to ensure a correct diagnostic definition, but taking always into account the benefit that the patient could obtain especially in terms of "therapeutic offer".
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Affiliation(s)
- Andrea Barp
- The NEMO Clinical Center in Milan, Neurorehabilitation Unit, University of Milan, Piazza Ospedale Maggiore 3, 20162 Milano, Italy
| | - Lorena Mosca
- Medical Genetics Unit, ASST Grande Ospedale Metropolitano Niguarda, Piazza Ospedale Maggiore 3, 20162 Milano, Italy
| | - Valeria Ada Sansone
- The NEMO Clinical Center in Milan, Neurorehabilitation Unit, University of Milan, Piazza Ospedale Maggiore 3, 20162 Milano, Italy
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19
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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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20
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François-Heude MC, Walther-Louvier U, Espil-Taris C, Beze-Beyrie P, Rivier F, Baudou E, Uro-Coste E, Rigau V, Martin Negrier ML, Rendu J, Morales RJ, Pégeot H, Thèze C, Lacourt D, Coville AC, Cossée M, Cances C. Evaluating next-generation sequencing in neuromuscular diseases with neonatal respiratory distress. Eur J Paediatr Neurol 2021; 31:78-87. [PMID: 33667896 DOI: 10.1016/j.ejpn.2021.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/18/2020] [Accepted: 01/19/2021] [Indexed: 02/09/2023]
Abstract
With the exception of infantile spinal muscular atrophy (SMA) and congenital myotonic dystrophy 1 (DM1), congenital myopathies and muscular dystrophies with neonatal respiratory distress pose diagnostic challenges. Next-generation sequencing (NGS) provides hope for the diagnosis of these rare diseases. We evaluated the efficiency of next-generation sequencing (NGS) in ventilated newborns with peripheral hypotonia. We compared the results of our previous study in a cohort of 19 patients analysed by Sanger sequencing from 2007 to 2012, with a diagnostic yield of 26% (5/19), and those of a new retrospective study in 28 patients from 2007 to 2018 diagnosed using MyoPanel, a neuromuscular disease panel, with a diagnostic yield of 43% (12/28 patients). Pathogenic variants were found in five genes: ACTA1 (n = 4 patients), RYR1 (n = 2), CACNA1S (n = 1), NEB (n = 3), and MTM1 (n = 2). Myopanel increased the diagnosis of congenital neuromuscular diseases, but more than half the patients remained undiagnosed. Whole exome sequencing did not seem to fully respond to this diagnostic limitation. Therefore, explorations with whole genome sequencing will be the next step.
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Affiliation(s)
- Marie-Céline François-Heude
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Toulouse University Hospital, Toulouse, France
| | - Ulrike Walther-Louvier
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Montpellier University Hospital, Montpellier, France
| | - Caroline Espil-Taris
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Bordeaux University Hospital, Aquitaine, France
| | | | - François Rivier
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Montpellier University Hospital, Montpellier, France
| | - Eloise Baudou
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Toulouse University Hospital, Toulouse, France
| | - Emmanuelle Uro-Coste
- Department of Pathology, Toulouse University Hospital, Toulouse, France; INSERM U1037, Cancer Research Centre of Toulouse (CRCT), Toulouse, France
| | - Valérie Rigau
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Aquitaine, France; Department of Pathology, Centre Hospitalier Universitaire Montpellier, Montpellier, France
| | | | - John Rendu
- INSERM U1216, Grenoble Alpes University Hospital, University of Grenoble Alpes, Grenoble, France
| | - Raul Juntas Morales
- Laboratory of Rare Genetic Diseases (LGMR), University of Montpellier, Montpellier, France
| | - Henri Pégeot
- Molecular Genetics Laboratory, Montpellier University Hospital Centre, Montpellier, France
| | - Corinne Thèze
- Molecular Genetics Laboratory, Montpellier University Hospital Centre, Montpellier, France
| | - Delphine Lacourt
- Molecular Genetics Laboratory, Montpellier University Hospital Centre, Montpellier, France
| | - Anne Cécile Coville
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Toulouse University Hospital, Toulouse, France
| | - Mireille Cossée
- Laboratory of Rare Genetic Diseases (LGMR), University of Montpellier, Montpellier, France; Molecular Genetics Laboratory, Montpellier University Hospital Centre, Montpellier, France
| | - Claude Cances
- AOC (Atlantique-Occitanie-Caraïbe) Reference Centre for Neuromuscular Disorders, Neuropaediatric Department, Toulouse University Hospital, Toulouse, France.
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21
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Herman I, Lopez MA, Marafi D, Pehlivan D, Calame DG, Abid F, Lotze TE. Clinical exome sequencing in the diagnosis of pediatric neuromuscular disease. Muscle Nerve 2020; 63:304-310. [PMID: 33146414 DOI: 10.1002/mus.27112] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 10/29/2020] [Accepted: 10/31/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND The diagnosis of uncommon pediatric neuromuscular disease (NMD) is challenging due to genetic and phenotypic heterogeneity, yet is important to guide treatment, prognosis, and recurrence risk. Patients with diagnostically challenging presentations typically undergo extensive testing with variable molecular diagnostic yield. Given the advancement in next generation sequencing (NGS), we investigated the value of clinical whole exome sequencing (ES) in uncommon pediatric NMD. METHODS A retrospective cohort study of 106 pediatric NMD patients with a combination of ES, chromosomal microarray (CMA), and candidate gene testing was completed at a large tertiary referral center. RESULTS A molecular diagnosis was achieved in 37/79 (46%) patients with ES, 4/44 (9%) patients with CMA, and 15/74 (20%) patients with candidate gene testing. In 2/79 (3%) patients, a dual molecular diagnosis explaining the neuromuscular disease process was identified. A total of 42 patients (53%) who received ES remained without a molecular diagnosis at the conclusion of the study. CONCLUSIONS Due to NGS, molecular diagnostic yield of rare neurological diseases is at an all-time high. We show that ES has a higher diagnostic rate compared to other genetic tests in a complex pediatric neuromuscular disease cohort and should be considered early in the diagnostic journey for select NMD patients with challenging presentations in which a clinical diagnosis is not evident.
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Affiliation(s)
- Isabella Herman
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine & Texas Children's Hospital, Houston, Texas, USA
| | - Michael A Lopez
- Department of Pediatrics, Division of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Dana Marafi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Davut Pehlivan
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine & Texas Children's Hospital, Houston, Texas, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Daniel G Calame
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine & Texas Children's Hospital, Houston, Texas, USA
| | - Farida Abid
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine & Texas Children's Hospital, Houston, Texas, USA
| | - Timothy E Lotze
- Department of Pediatrics, Section of Pediatric Neurology and Developmental Neuroscience, Baylor College of Medicine & Texas Children's Hospital, Houston, Texas, USA
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22
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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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23
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Clinical exome sequencing in neuromuscular diseases: an experience from Turkey. Neurol Sci 2020; 41:2157-2164. [PMID: 32140910 DOI: 10.1007/s10072-020-04304-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 02/20/2020] [Indexed: 02/08/2023]
Abstract
Neuromuscular diseases (NMDs) encompass a variety of ailments from muscular dystrophies to ataxias, in the course of which the functioning of the muscles is eventually either directly or indirectly impaired. The clinical diagnosis of a particular NMD is not always straightforward due to the clinical and genetic heterogeneity of the disorders under investigation. Traditional diagnostic tools such as electrophysiological tests and muscle biopsies are both invasive and painful methods, causing the patients to be reluctant. Next-generation sequencing, on the other hand, emerged as an alternative method for the diagnosis of NMDs, both with its minimally invasive nature and fast processing period. In this study, clinical exome sequencing (CES) was applied to a cohort of 70 probands in Turkey, 44 of whom received a final diagnosis, representing a diagnostic rate of 62.9%. Out of the 50 mutations identified to be causal, 26 were novel in the known 27 NMD genes. Two probands had complex/blended phenotypes. Molecular confirmation of clinical diagnosis of NMDs has a major prognostic impact and is crucial for the management and the possibility of alternative reproductive options. CES, which has been increasingly adopted to diagnose single-gene disorders, is also a powerful tool for revealing the etiopathogenesis in complex/blended phenotypes, as observed in two probands of the cohort.
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24
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Pellerin D, Aykanat A, Ellezam B, Troiano EC, Karamchandani J, Dicaire MJ, Petitclerc M, Robertson R, Allard-Chamard X, Brunet D, Konersman CG, Mathieu J, Warman Chardon J, Gupta VA, Beggs AH, Brais B, Chrestian N. Novel Recessive TNNT1 Congenital Core-Rod Myopathy in French Canadians. Ann Neurol 2020; 87:568-583. [PMID: 31970803 DOI: 10.1002/ana.25685] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 01/06/2020] [Accepted: 01/19/2020] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Recessive null variants of the slow skeletal muscle troponin T1 (TNNT1) gene are a rare cause of nemaline myopathy that is fatal in infancy due to respiratory insufficiency. Muscle biopsy shows rods and fiber type disproportion. We report on 4 French Canadians with a novel form of recessive congenital TNNT1 core-rod myopathy. METHODS Patients underwent full clinical characterization, lower limb magnetic resonance imaging (MRI), muscle biopsy, and genetic testing. A zebrafish loss-of-function model using morpholinos was created to assess the pathogenicity of the identified variant. Wild-type or mutated human TNNT1 mRNAs were coinjected with morpholinos to assess their abilities to rescue the morphant phenotype. RESULTS Three adults and 1 child shared a novel missense homozygous variant in the TNNT1 gene (NM_003283.6: c.287T > C; p.Leu96Pro). They developed from childhood very slowly progressive limb-girdle weakness with rigid spine and disabling contractures. They suffered from restrictive lung disease requiring noninvasive mechanical ventilation in 3 patients, as well as recurrent episodes of rhabdomyolysis triggered by infections, which were relieved by dantrolene in 1 patient. Older patients remained ambulatory into their 60s. MRI of the leg muscles showed fibrofatty infiltration predominating in the posterior thigh and the deep posterior leg compartments. Muscle biopsies showed multiminicores and lobulated fibers, rods in half the patients, and no fiber type disproportion. Wild-type TNNT1 mRNA rescued the zebrafish morphants, but mutant transcripts failed to do so. INTERPRETATION This study expands the phenotypic spectrum of TNNT1 myopathy and provides functional evidence for the pathogenicity of the newly identified missense mutation. ANN NEUROL 2020;87:568-583.
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Affiliation(s)
- David Pellerin
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | - Asli Aykanat
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Benjamin Ellezam
- Department of Pathology, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montreal, Quebec, Canada
| | - Emily C Troiano
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Jason Karamchandani
- Department of Pathology, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | - Marie-Josée Dicaire
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | - Marc Petitclerc
- Department of Neurology, Hôpital Hôtel-Dieu de Lévis, Lévis, Quebec, Canada
| | - Rebecca Robertson
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | - Xavier Allard-Chamard
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | - Denis Brunet
- Department of Neurology, Hôpital de l'Enfant Jésus, Université Laval, Quebec City, Quebec, Canada
| | | | - Jean Mathieu
- Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.,Neuromuscular Disease Clinic, Centre Intégré Universitaire de Santé et de Services Sociaux du Saguenay-Lac-Saint-Jean, Jonquière, Quebec, Canada
| | - Jodi Warman Chardon
- Department of Neurosciences, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Vandana A Gupta
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Bernard Brais
- Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada.,Neuromuscular Disease Clinic, Centre Intégré Universitaire de Santé et de Services Sociaux du Saguenay-Lac-Saint-Jean, Jonquière, Quebec, Canada.,Department of Human Genetics, McGill University, Montreal, Quebec, Canada
| | - Nicolas Chrestian
- Department of Child Neurology, Centre Hospitalier de l'Université Laval et Centre Mère-Enfant Soleil, Université Laval, Quebec City, Quebec, Canada
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Dardas Z, Swedan S, Al-Sheikh Qassem A, Azab B. The impact of exome sequencing on the diagnostic yield of muscular dystrophies in consanguineous families. Eur J Med Genet 2020; 63:103845. [PMID: 31953240 DOI: 10.1016/j.ejmg.2020.103845] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/04/2019] [Accepted: 01/11/2020] [Indexed: 10/25/2022]
Abstract
Muscular dystrophies (MDs) are a heterogeneous group of inherited disorders that are characterized by progressive skeletal muscle weakness and dystrophic changes on muscle biopsy. The broad genetic and clinical heterogeneity of MDs make the accurate diagnosis difficult via conventional approaches. This study investigated 23 patients from eight unrelated consanguineous families with MDs. Previous clinical assessments did not accurately clarify the type of their MD and/or misdiagnose them with another disease. Exome sequencing (ES) is an efficient, time-saving, and cost-effective tool, enabling disease-causing variant (DCV) detection in affected individuals. We investigated the use of ES to diagnose MD and discover the underlying genetic etiology. We achieved a remarkable diagnostic success rate of 87.5% (7 out of 8 families) which is the highest rate reported thus far compared to previous studies. We identified two novel pathogenic variants in DYSF gene (c.4179delG, c.1149+3G > C). The latter variant impacts the splicing machinery of DYSF mRNA. Moreover, we further assessed the pathogenicity of four recurrent variants ((DYSF, c.4076T > C), (GMPPB, c.458C > T), (SGCA, c.739G > A) (TTN, c.7331G > A), designated their neurological impact and added new phenotypes in patients with these variants. To our knowledge, this is the first study applying an ES-based comprehensive molecular diagnosis to Jordanian cohort with MDs. Our findings confirmed that ES is a powerful approach for the diagnosis of MD patients. This efficient method of molecular diagnosis is crucial for guiding patient clinical care, genetic counseling, and most importantly, paving the way for gene therapy which is currently in clinical trials.
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Affiliation(s)
- Zain Dardas
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan; Department of Pathology and Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman, Jordan.
| | - Samer Swedan
- Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, Jordan University of Science and Technology, Irbid, Jordan
| | | | - Belal Azab
- Department of Pathology and Microbiology and Forensic Medicine, School of Medicine, The University of Jordan, Amman, Jordan; Human and Molecular Genetics, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA.
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Mojbafan M, Bahmani R, Bagheri SD, Sharifi Z, Zeinali S. Mutational spectrum of autosomal recessive limb-girdle muscular dystrophies in a cohort of 112 Iranian patients and reporting of a possible founder effect. Orphanet J Rare Dis 2020; 15:14. [PMID: 31937337 PMCID: PMC6961257 DOI: 10.1186/s13023-020-1296-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 01/05/2020] [Indexed: 11/10/2022] Open
Abstract
Background Limb-girdle muscular dystrophies are a group of genetically heterogeneous diseases that are inherited in both autosomal dominant (LGMDD) and autosomal recessive forms (LGMDR), the latter is more common especially in populations with high consanguineous marriages like Iran. In the present study, we aimed to investigate the genetic basis of patients who are suspicious of being affected by LGMDR. DNA samples of 60 families suspected of LGMD were extracted from their whole blood. Four short tandem repeat (STR) markers for each candidate genes related to LGMD R1 (calpain3 related)- R6 (δ-sarcoglycan-related) were selected, and all these 24 STRs were applied in two sets of multiplex PCR. After autozygosity mapping, Sanger sequencing and variant analysis were done. Predicting identified variants’ effect was performed using in-silico tools, and they were interpreted according to the American College of Medical Genomics and Genetics (ACMG) guideline. MLPA was used for those patients who had large deletions. Fresh muscle specimens were taken from subjects and were evaluated using the conventional panel of histochemical stains. Results forty out of sixty families showed homozygote haplotypes in CAPN3, DYSF, SGCA, and SGCB genes. The exons and intron-exon boundaries of the relevant genes were sequenced and totally 38 mutations including CAPN3 (n = 15), DYSF (n = 9), SGCB (n = 11), and SGCA (n = 3) were identified. Five out of them were novel. The most prevalent form of LGMDs in our study was calpainopathy followed by sarcoglycanopathy in which beta-sarcoglycanopathy was the most common form amongst them. Exon 2 deletion in the SGCB gene was the most frequent mutation in this study. We also reported evidence of a possible founder effect in families with mutations in DYSF and SGCB genes. We also detected a large consanguineous family suffered from calpainopathy who showed allelic heterogeneity. Conclusions This study can expand our knowledge about the genetic spectrum of LGMD in Iran, and also suggest the probable founder effects in some Iranian subpopulations which confirming it with more sample size can facilitate our genetic diagnosis and genetic counseling.
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Affiliation(s)
- Marzieh Mojbafan
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Shahid Hemmat Highway, Tehran, Iran.,Department of Medical Genetics, Ali-Asghar Children's Hospital, Zafar St., Shahid Modarres Highway, Tehran, Iran
| | - Reza Bahmani
- Department of Medical Genetics and Molecular Biology, Faculty of Medicine, Iran University of Medical Sciences (IUMS), Shahid Hemmat Highway, Tehran, Iran.,Student Research Committee, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Samira Dabbagh Bagheri
- Dr. Zeinali's Medical Genetics Laboratory, Kawsar Human Genetics Research Center, Tehran, Iran
| | - Zohreh Sharifi
- Dr. Zeinali's Medical Genetics Laboratory, Kawsar Human Genetics Research Center, Tehran, Iran.,Department of Genetics, Faculty of Advanced Science and Technology, Tehran Medical Sciences, Islamic Azad University, Tehran, Iran
| | - Sirous Zeinali
- Dr. Zeinali's Medical Genetics Laboratory, Kawsar Human Genetics Research Center, Tehran, Iran. .,Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, No. 69, Pasteur Ave, Tehran, Iran.
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D'Amico A, Fattori F, Fiorillo C, Paglietti MG, Testa MBC, Verardo M, Catteruccia M, Bruno C, Bertini E. 'Amish Nemaline Myopathy' in 2 Italian siblings harbouring a novel homozygous mutation in Troponin-I gene. Neuromuscul Disord 2019; 29:766-770. [PMID: 31604653 DOI: 10.1016/j.nmd.2019.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/10/2019] [Accepted: 09/02/2019] [Indexed: 02/06/2023]
Abstract
Amish Nemaline Myopathy is a severe form of nemaline myopathy associated to mutation in TNNT1 gene, firstly reported among the Old Order Amish. Here we report two Italian siblings who manifested, by the age of 7 months, progressive and severe muscle weakness and wasting, respiratory insufficiency, pectus carinatum deformity and failure to thrive. Muscle biopsy was consistent with nemaline myopathy and novel homozygous missense mutation in TNNT1 was found. Our cases expand the mutational spectrum of TNNT1, confirm the invariable peculiar clinical phenotype also outside the Amish population, and suggest that TNNT1 should be considered for molecular analysis in NM patients with chest deformities and progressive contractures.
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Affiliation(s)
- Adele D'Amico
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences and Neurorehabilitation, Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Fabiana Fattori
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences and Neurorehabilitation, Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy
| | - Chiara Fiorillo
- Paediatric Neurology and Neuromuscular Disorders Unit, Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Istituto Giannina Gaslini, Genoa, Italy
| | - Maria Giovanna Paglietti
- Respiratory Unit, Academic Department of Pediatrics, Bambino Gesù Children's Hospital, IRCCS, Piazza di Sant' Onofrio 4, 00165 Rome, Italy
| | - Maria Beatrice Chiarini Testa
- Respiratory Unit, Academic Department of Pediatrics, Bambino Gesù Children's Hospital, IRCCS, Piazza di Sant' Onofrio 4, 00165 Rome, Italy
| | - Margherita Verardo
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences and Neurorehabilitation, Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy
| | - Michela Catteruccia
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences and Neurorehabilitation, Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy
| | - Claudio Bruno
- Center of Translational and Experimental Myology, Istituto Giannina Gaslini, Genova, Italy
| | - Enrico Bertini
- Unit of Muscular and Neurodegenerative Disorders, Department of Neurosciences and Neurorehabilitation, Bambino Gesù Children's Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy
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28
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Krenn M, Tomschik M, Rath J, Cetin H, Grisold A, Zulehner G, Milenkovic I, Stogmann E, Zimprich A, Strom TM, Meitinger T, Wagner M, Zimprich F. Genotype-guided diagnostic reassessment after exome sequencing in neuromuscular disorders: experiences with a two-step approach. Eur J Neurol 2019; 27:51-61. [PMID: 31407473 PMCID: PMC6916592 DOI: 10.1111/ene.14033] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 07/05/2019] [Indexed: 01/03/2023]
Abstract
Background and purpose Next‐generation sequencing has greatly improved the diagnostic success rates for genetic neuromuscular disorders (NMDs). Nevertheless, most patients still remain undiagnosed, and there is a need to maximize the diagnostic yield. Methods A retrospective study was conducted on 72 patients with NMDs who underwent exome sequencing (ES), partly followed by genotype‐guided diagnostic reassessment and secondary investigations. The diagnostic yields that would have been achieved by appropriately chosen narrow and comprehensive gene panels were also analysed. Results The initial diagnostic yield of ES was 30.6% (n = 22/72 patients). In an additional 15.3% of patients (n = 11/72) ES results were of unknown clinical significance. After genotype‐guided diagnostic reassessment and complementary investigations, the yield was increased to 37.5% (n = 27/72). Compared to ES, targeted gene panels (<25 kilobases) reached a diagnostic yield of 22.2% (n = 16/72), whereas comprehensive gene panels achieved 34.7% (n = 25/72). Conclusion Exome sequencing allows the detection of pathogenic variants missed by (narrowly) targeted gene panel approaches. Diagnostic reassessment after genetic testing further enhances the diagnostic outcomes for NMDs.
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Affiliation(s)
- M Krenn
- Department of Neurology, Medical University of Vienna, Vienna, Austria.,Institute of Human Genetics, Technical University Munich, Munich, Germany
| | - M Tomschik
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - J Rath
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - H Cetin
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - A Grisold
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - G Zulehner
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - I Milenkovic
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - E Stogmann
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - A Zimprich
- Department of Neurology, Medical University of Vienna, Vienna, Austria
| | - T M Strom
- Institute of Human Genetics, Technical University Munich, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - T Meitinger
- Institute of Human Genetics, Technical University Munich, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - M Wagner
- Institute of Human Genetics, Technical University Munich, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany
| | - F Zimprich
- Department of Neurology, Medical University of Vienna, Vienna, Austria
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29
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Al-Dewik N, Mohd H, Al-Mureikhi M, Ali R, Al-Mesaifri F, Mahmoud L, Shahbeck N, El-Akouri K, Almulla M, Al Sulaiman R, Musa S, Al-Marri AAN, Richard G, Juusola J, Solomon BD, Alkuraya FS, Ben-Omran T. Clinical exome sequencing in 509 Middle Eastern families with suspected Mendelian diseases: The Qatari experience. Am J Med Genet A 2019; 179:927-935. [PMID: 30919572 PMCID: PMC6916397 DOI: 10.1002/ajmg.a.61126] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 01/22/2019] [Accepted: 02/25/2019] [Indexed: 12/24/2022]
Abstract
BACKGROUND Clinical exome sequencing (CES) is rapidly becoming the diagnostic test of choice in patients with suspected Mendelian diseases especially those that are heterogeneous in etiology and clinical presentation. Reporting large CES series can inform guidelines on best practices for test utilization, and improves accuracy of variant interpretation through clinically-oriented data sharing. METHODS This is a retrospective series of 509 probands from Qatar who underwent singleton or trio CES either as a reflex or naïve (first-tier) test from April 2014 to December 2016 for various clinical indications. RESULTS The CES diagnostic yield for the overall cohort was 48.3% (n = 246). Dual molecular diagnoses were observed in 2.1% of cases; nearly all of whom (91%) were consanguineous. We report compelling variants in 11 genes with no established Mendelian phenotypes. Unlike reflex-WES, naïve WES was associated with a significantly shorter diagnostic time (3 months vs. 18 months, p < 0.0001). CONCLUSION Middle Eastern patients tend to have a higher yield from CES than outbred populations, which has important implications in test choice especially early in the diagnostic process. The relatively high diagnostic rate is likely related to the predominance of recessive diagnoses (60%) since consanguinity and positive family history were strong predictors of a positive CES.
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Affiliation(s)
- Nader Al-Dewik
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar.,College of Health and Life Sciences, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Howaida Mohd
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Mariam Al-Mureikhi
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Rehab Ali
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Fatma Al-Mesaifri
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Laila Mahmoud
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Noora Shahbeck
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Karen El-Akouri
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Mariam Almulla
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Reem Al Sulaiman
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | - Sara Musa
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar
| | | | - Gabriele Richard
- Clinical Genomics Program, GeneDx, Inc., Gaithersburg, Maryland, USA
| | - Jane Juusola
- Clinical Genomics Program, GeneDx, Inc., Gaithersburg, Maryland, USA
| | | | - Fowzan S Alkuraya
- Department of Genetics, Research Center, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Tawfeg Ben-Omran
- Clinical and Metabolic Genetics, Department of Pediatrics, Hamad Medical Corporation, Doha, Qatar.,Department of pediatric, Weill Cornell Medical College, Doha, Qatar.,Division of Genetic & Genomics Medicine, Sidra Medicine, Doha, Qatar
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30
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Genomics and Precision Medicine: Molecular Diagnostics Innovations Shaping the Future of Healthcare in Qatar. ADVANCES IN PUBLIC HEALTH 2019. [DOI: 10.1155/2019/3807032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Unprecedented developments in genomics research and ancillary technologies are creating the potential for astonishing changes in both the healthcare field and the life sciences sector. The innovative genomics applications include the following: (1) embracing next generation sequencing (NGS) in clinical diagnostics setting (applying both whole genome and exome sequencing), (2) single cell sequencing studies, (3) quantifying gene expression changes (including whole transcriptome sequencing), (4) pharmacogenomics, and (5) cell-free DNA blood-based testing. This minireview describes the impact of clinical genomics disruptive innovations on the healthcare system in order to provide better diagnosis and treatment. The observed evolution is not limited to the point-of-care services. Genomics technological breakthroughs are pushing the healthcare environment towards personalized healthcare with the real potential to attain better wellbeing. In this article, we will briefly discuss the Gulf region population-based genome initiatives that intend to improve personalized healthcare by offering better prevention, diagnosis, and therapy for the individual (precision medicine). Qatar’s endeavor in genomics medicine will be underscored including the private Applied Biomedicine Initiative (ABI).
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31
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Fox MD, Carson VJ, Feng HZ, Lawlor MW, Gray JT, Brigatti KW, Jin JP, Strauss KA. TNNT1 nemaline myopathy: natural history and therapeutic frontier. Hum Mol Genet 2019; 27:3272-3282. [PMID: 29931346 DOI: 10.1093/hmg/ddy233] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/06/2018] [Indexed: 02/03/2023] Open
Abstract
We describe the natural history of 'Amish' nemaline myopathy (ANM), an infantile-onset, lethal disease linked to a pathogenic c.505G>T nonsense mutation of TNNT1, which encodes the slow fiber isoform of troponin T (TNNT1; a.k.a. TnT). The TNNT1 c.505G>T allele has a carrier frequency of 6.5% within Old Order Amish settlements of North America. We collected natural history data for 106 ANM patients born between 1923 and 2017. Over the last two decades, mean age of molecular diagnosis was 16 ± 27 days. TNNT1 c.505G>T homozygotes were normal weight at birth but failed to thrive by age 9 months. Presenting neonatal signs were axial hypotonia, hip and shoulder stiffness, and tremors, followed by progressive muscle weakness, atrophy and contractures. Affected children developed thoracic rigidity, pectus carinatum and restrictive lung disease during infancy, and all succumbed to respiratory failure by 6 years of age (median survival 18 months, range 0.2-66 months). Muscle histology from two affected children showed marked fiber size variation owing to both Type 1 myofiber smallness (hypotrophy) and Type 2 fiber hypertrophy, with evidence of nemaline rods, myofibrillar disarray and vacuolar pathology in both fiber types. The truncated slow TNNT1 (TnT) fragment (p.Glu180Ter) was undetectable in ANM muscle, reflecting its rapid proteolysis and clearance from sarcoplasm. Similar functional and histological phenotypes were observed in other human cohorts and two transgenic murine models (Tnnt1-/- and Tnnt1 c.505G>T). These findings have implications for emerging molecular therapies, including the suitably of TNNT1 gene replacement for newborns with ANM or other TNNT1-associated myopathies.
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Affiliation(s)
- Michael D Fox
- Clinic for Special Children, Strasburg, PA, USA
- Department of Pediatrics, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, PA, USA
- Diagnostic Referral Division, Nemours/Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | | | - Han-Zhong Feng
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Michael W Lawlor
- Department of Pathology and Laboratory Medicine and Neuroscience Research Center, The Medical College of Wisconsin, Milwaukee, WI, USA
| | - John T Gray
- Audentes Therapeutics, San Francisco, CA, USA
| | | | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
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Streff H, Bi W, Colón AG, Adesina AM, Miyake CY, Lalani SR. Amish nemaline myopathy and dilated cardiomyopathy caused by a homozygous contiguous gene deletion of TNNT1 and TNNI3 in a Mennonite child. Eur J Med Genet 2018; 62:103567. [PMID: 30395933 DOI: 10.1016/j.ejmg.2018.11.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 10/05/2018] [Accepted: 11/01/2018] [Indexed: 12/28/2022]
Abstract
Amish nemaline myopathy (ANM) is a severe congenital form of NM, known to be fatal in early childhood due to pulmonary insufficiency. Homozygous mutation in TNNT1 was originally ascertained in an Older Amish community in 2000. To date, only five reports with six pathogenic variants in TNNT1 have been described in both Amish and non-Amish families. Here, we describe a 16-month old female from a small Mennonite community from Mexico, presenting with congenital hypotonia and dilated cardiomyopathy, with a novel homozygous deletion of 19q13.42 of about 11 kb in size, encompassing TNNT1 and TNNI3. Cardiomyopathy has not been observed in association with ANM in previous reports. Conversely, homozygous mutation in TNNI3 have been described with dilated cardiomyopathy. Our report underscores the consideration of contiguous gene deletion in children with ANM who present with congenital hypotonia and cardiomyopathy. The report also expands the known spectrum of non-Amish related ANM mutations to include homozygous multi-exonic TNNT1 deletion.
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Affiliation(s)
- Haley Streff
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Weimin Bi
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA; Baylor Genetics Laboratories, Houston, TX, 77030, USA
| | - Athos G Colón
- Department of Pediatrics, Texas Tech University School of Medicine, Lubbock, TX, 79430, USA
| | - Adekunle M Adesina
- Department of Pathology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Christina Y Miyake
- Division of Cardiology, Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Seema R Lalani
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.
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Weiss K, Kurolap A, Paperna T, Mory A, Steinberg M, Hershkovitz T, Ekhilevitch N, Baris HN. Rare Disease Diagnostics: A Single-center Experience and Lessons Learnt. Rambam Maimonides Med J 2018; 9:RMMJ.10341. [PMID: 30089087 PMCID: PMC6115477 DOI: 10.5041/rmmj.10341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE The growing availability of next-generation sequencing technologies has revolutionized medical genetics, facilitating discovery of causative genes in numerous Mendelian disorders. Nevertheless, there are still many undiagnosed cases. We report the experience of the Genetics Institute at Rambam Health Care Campus in rare disease diagnostics using whole-exome sequencing (WES). METHODS Phenotypic characterization of patients was done in close collaboration with referring physicians. We utilized WES analysis for diagnosing families suspected for rare genetic disorders. Bioinformatic analysis was performed in-house using the Genoox analysis platform. RESULTS Between the years 2014 and 2017, we studied 34 families. Neurological manifestations were the most common reason for referral (38%), and 55% of families were consanguineous. A definite diagnosis was reached in 21 cases (62%). Four cases (19%) were diagnosed with variants in novel genes. In addition, six families (18%) had strong candidate novel gene discoveries still under investigation. Therefore, the true diagnosis rate is probably even higher. Some of the diagnoses had a significant impact such as alerting the patient management and providing a tailored treatment. CONCLUSIONS An accurate molecular diagnosis can set the stage for improved patient care and provides an opportunity to study disease mechanisms, which may lead to development of tailored treatments. Data from our genetic research program demonstrate high diagnostic and novel disease-associated or causative gene discovery rates. This is likely related to the unique genetic architecture of the population in Northern Israel as well as to our strategy for case selection and the close collaboration between analysts, geneticists, and clinicians, all working in the same hospital.
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Affiliation(s)
- Karin Weiss
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
| | - Alina Kurolap
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion–Israel Institute of Technology, Haifa, Israel
| | - Tamar Paperna
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
| | - Adi Mory
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
| | - Maya Steinberg
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
| | - Tova Hershkovitz
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
| | - Nina Ekhilevitch
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
| | - Hagit N. Baris
- The Genetics Institute, Rambam Health Care Center, Haifa, Israel
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion–Israel Institute of Technology, Haifa, Israel
- To whom correspondence should be addressed. E-mail:
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Abstract
PURPOSE OF REVIEW The development of massively parallel sequencing (MPS) has revolutionized molecular genetic diagnostics in monogenic disorders. The present review gives a brief overview of different MPS-based approaches used in clinical diagnostics of neuromuscular disorders (NMDs) and highlights their advantages and limitations. RECENT FINDINGS MPS-based approaches like gene panel sequencing, (whole) exome sequencing, (whole) genome sequencing, and RNA sequencing have been used to identify the genetic cause in NMDs. Although gene panel sequencing has evolved as a standard test for heterogeneous diseases, it is still debated, mainly because of financial issues and unsolved problems of variant interpretation, whether genome sequencing (and to a lesser extent also exome sequencing) of single patients can already be regarded as routine diagnostics. However, it has been shown that the inclusion of parents and additional family members often leads to a substantial increase in the diagnostic yield in exome-wide/genome-wide MPS approaches. In addition, MPS-based RNA sequencing just enters the research and diagnostic scene. SUMMARY Next-generation sequencing increasingly enables the detection of the genetic cause in highly heterogeneous diseases like NMDs in an efficient and affordable way. Gene panel sequencing and family-based exome sequencing have been proven as potent and cost-efficient diagnostic tools. Although clinical validation and interpretation of genome sequencing is still challenging, diagnostic RNA sequencing represents a promising tool to bypass some hurdles of diagnostics using genomic DNA.
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Angelini C, Fanin M. Limb girdle muscular dystrophies: clinical-genetical diagnostic update and prospects for therapy. Expert Opin Orphan Drugs 2017. [DOI: 10.1080/21678707.2017.1367283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Corrado Angelini
- Department of Neurodegenerative Disorders, Neuromuscular Center, San Camillo Hospital IRCCS, Venice, Italy
| | - Marina Fanin
- Department of Neurosciences, University of Padova, Padova, Italy
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Alavi A, Esmaeili S, Nilipour Y, Nafissi S, Tonekaboni SH, Zamani G, Ashrafi MR, Kahrizi K, Najmabadi H, Jazayeri F. LGMD2E is the most common type of sarcoglycanopathies in the Iranian population. J Neurogenet 2017; 31:161-169. [DOI: 10.1080/01677063.2017.1346093] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Afagh Alavi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Sara Esmaeili
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Yalda Nilipour
- Pediatric Pathology Research Center, Mofid Children Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shahriar Nafissi
- Department of Neurology, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyed Hasan Tonekaboni
- Pediatric Neurology Center of Excellence, Department of Pediatric Neurology, Mofid Children Hospital, Faculty of Medicine, Shahid Beheshti Medical university, Tehran, Iran
| | - Gholamreza Zamani
- Children's Medical Center, Tehran University of Medical Sciences, Iranian Epilepsy Association Board, Tehran, Iran
| | - Mahmoud Reza Ashrafi
- Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Fatemeh Jazayeri
- Department of Neurology, Tehran University of Medical Sciences, Tehran, Iran
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The sensitivity of exome sequencing in identifying pathogenic mutations for LGMD in the United States. J Hum Genet 2016; 62:243-252. [PMID: 27708273 PMCID: PMC5266644 DOI: 10.1038/jhg.2016.116] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 08/31/2016] [Accepted: 09/02/2016] [Indexed: 01/12/2023]
Abstract
The current study characterizes a cohort of limb-girdle muscular dystrophy (LGMD) in the United States using whole exome sequencing. Fifty-five families affected by LGMD were recruited using an institutionally-approved protocol. Exome sequencing was performed on probands and selected parental samples. Pathogenic mutations and co-segregation patterns were confirmed by Sanger sequencing. Twenty-two families (40%) had novel and previously reported pathogenic mutations, primarily in LGMD genes, but also in genes for Duchenne muscular dystrophy, facioscapulohumeral muscular dystrophy, congenital myopathy, myofibrillar myopathy, inclusion body myopathy, and Pompe disease. One family was diagnosed via clinical testing. Dominant mutations were identified in COL6A1, COL6A3, FLNC, LMNA, RYR1, SMCHD1, and VCP, recessive mutations in ANO5, CAPN3, GAA, LAMA2, SGCA, and SGCG, and X-linked mutations in DMD. A previously reported variant in DMD was confirmed to be benign. Exome sequencing is a powerful diagnostic tool for LGMD. Despite careful phenotypic screening, pathogenic mutations were found in other muscle disease genes, largely accounting for the increased sensitivity of exome sequencing. Our experience suggests that broad sequencing panels are useful for these analyses due to the phenotypic overlap of many neuromuscular conditions. The confirmation of a benign DMD variant illustrates the potential of exome sequencing to help determine pathogenicity.
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