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Abstract
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. © 2017 American Physiological Society. Compr Physiol 7:891-944, 2017.
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Affiliation(s)
- Christine A Henderson
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Christopher G Gomez
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Stefanie M Novak
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Lei Mi-Mi
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
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Gómez J, Lorca R, Reguero JR, Morís C, Martín M, Tranche S, Alonso B, Iglesias S, Alvarez V, Díaz-Molina B, Avanzas P, Coto E. Screening of the Filamin C Gene in a Large Cohort of Hypertrophic Cardiomyopathy Patients. ACTA ACUST UNITED AC 2017; 10:CIRCGENETICS.116.001584. [PMID: 28356264 DOI: 10.1161/circgenetics.116.001584] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 01/11/2017] [Indexed: 01/26/2023]
Abstract
BACKGROUND Recent exome sequencing studies identified filamin C (FLNC) as a candidate gene for hypertrophic cardiomyopathy (HCM). Our aim was to determine the rate of FLNC candidate variants in a large cohort of HCM patients who were also sequenced for the main sarcomere genes. METHODS AND RESULTS A total of 448 HCM patients were next generation-sequenced (semiconductor chip technology) for the MYH7, MYBPC3, TNNT2, TNNI3, ACTC1, TNNC1, MYL2, MYL3, TPM1, and FLNC genes. We also sequenced 450 healthy controls from the same population. Based on the reported population frequencies, bioinformatic criteria, and familial segregation, we identified 20 FLNC candidate variants (13 new; 1 nonsense; and 19 missense) in 22 patients. Compared with the patients, only 1 of the control's missense variants was nonreported (P=0.007; Fisher exact probability test). Based on the familial segregation and the reported functional studies, 6 of the candidate variants (in 7 patients) were finally classified as likely pathogenic, 10 as variants of uncertain significance, and 4 as likely benign. CONCLUSIONS We provide a compelling evidence of the involvement of FLNC in the development of HCM. Most of the FLNC variants were associated with mild forms of HCM and a reduced penetrance, with few affected in the families to confirm the segregation. Our work, together with others who found FLNC variants among patients with dilated and restrictive cardiomyopathies, pointed to this gene as an important cause of structural cardiomyopathies.
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Affiliation(s)
- Juan Gómez
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Rebeca Lorca
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Julian R Reguero
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - César Morís
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - María Martín
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Salvador Tranche
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Belén Alonso
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Sara Iglesias
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Victoria Alvarez
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Beatriz Díaz-Molina
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Pablo Avanzas
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.)
| | - Eliecer Coto
- From the Unidad de Referencia de Cardiopatías Familiares-HUCA, Genética Molecular y Cardiología, Hospital Universitario Central Asturias, Oviedo, Spain (J.G., R.L., J.R.R., C.M., M.M., B.A., S.I., V.A., B.D.-M., P.A., E.C.); Fundación Asturcor, Spain (J.R.R., C.M.); Departamento de Medicina, Universidad de Oviedo, Spain (C.M., E.C.); Centro Salud El Cristo, Oviedo, Spain (S.T.); and Red de Investigación Renal (REDINREN), Madrid, Spain (E.C.).
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Veltri T, Landim-Vieira M, Parvatiyar MS, Gonzalez-Martinez D, Dieseldorff Jones KM, Michell CA, Dweck D, Landstrom AP, Chase PB, Pinto JR. Hypertrophic Cardiomyopathy Cardiac Troponin C Mutations Differentially Affect Slow Skeletal and Cardiac Muscle Regulation. Front Physiol 2017; 8:221. [PMID: 28473771 PMCID: PMC5397416 DOI: 10.3389/fphys.2017.00221] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/27/2017] [Indexed: 12/22/2022] Open
Abstract
Mutations in TNNC1-the gene encoding cardiac troponin C (cTnC)-that have been associated with hypertrophic cardiomyopathy (HCM) and cardiac dysfunction may also affect Ca2+-regulation and function of slow skeletal muscle since the same gene is expressed in both cardiac and slow skeletal muscle. Therefore, we reconstituted rabbit soleus fibers and bovine masseter myofibrils with mutant cTnCs (A8V, C84Y, E134D, and D145E) associated with HCM to investigate their effects on contractile force and ATPase rates, respectively. Previously, we showed that these HCM cTnC mutants, except for E134D, increased the Ca2+ sensitivity of force development in cardiac preparations. In the current study, an increase in Ca2+ sensitivity of isometric force was only observed for the C84Y mutant when reconstituted in soleus fibers. Incorporation of cTnC C84Y in bovine masseter myofibrils reduced the ATPase activity at saturating [Ca2+], whereas, incorporation of cTnC D145E increased the ATPase activity at inhibiting and saturating [Ca2+]. We also tested whether reconstitution of cardiac fibers with troponin complexes containing the cTnC mutants and slow skeletal troponin I (ssTnI) could emulate the slow skeletal functional phenotype. Reconstitution of cardiac fibers with troponin complexes containing ssTnI attenuated the Ca2+ sensitization of isometric force when cTnC A8V and D145E were present; however, it was enhanced for C84Y. In summary, although the A8V and D145E mutants are present in both muscle types, their functional phenotype is more prominent in cardiac muscle than in slow skeletal muscle, which has implications for the protein-protein interactions within the troponin complex. The C84Y mutant warrants further investigation since it drastically alters the properties of both muscle types and may account for the earlier clinical onset in the proband.
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Affiliation(s)
- Tiago Veltri
- Department of Biomedical Sciences, Florida State University College of MedicineTallahassee, FL, USA
| | - Maicon Landim-Vieira
- Department of Biomedical Sciences, Florida State University College of MedicineTallahassee, FL, USA
| | - Michelle S. Parvatiyar
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of MedicineMiami, FL, USA
| | - David Gonzalez-Martinez
- Department of Biomedical Sciences, Florida State University College of MedicineTallahassee, FL, USA
| | | | - Clara A. Michell
- Department of Biomedical Sciences, Florida State University College of MedicineTallahassee, FL, USA
| | - David Dweck
- Department of Biomedical Sciences, Florida State University College of MedicineTallahassee, FL, USA
| | - Andrew P. Landstrom
- Section of Pediatric Cardiology, Department of Pediatrics, Baylor College of MedicineHouston, TX, USA
| | - P. Bryant Chase
- Department of Biological Science, Florida State UniversityTallahassee, FL, USA
| | - Jose R. Pinto
- Department of Biomedical Sciences, Florida State University College of MedicineTallahassee, FL, USA
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Myosin Storage Myopathy in C. elegans and Human Cultured Muscle Cells. PLoS One 2017; 12:e0170613. [PMID: 28125727 PMCID: PMC5268365 DOI: 10.1371/journal.pone.0170613] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 01/06/2017] [Indexed: 02/06/2023] Open
Abstract
Myosin storage myopathy is a protein aggregate myopathy associated with the characteristic subsarcolemmal accumulation of myosin heavy chain in muscle fibers. Despite similar histological findings, the clinical severity and age of onset are highly variable, ranging from no weakness to severe impairment of ambulation, and usually childhood-onset to onset later in life. Mutations located in the distal end of the tail of slow/ß-cardiac myosin heavy chain are associated with myosin storage myopathy. Four missense mutations (L1793P, R1845W, E1883K and H1901L), two of which have been reported in several unrelated families, are located within or closed to the assembly competence domain. This location is critical for the proper assembly of sarcomeric myosin rod filaments. To assess the mechanisms leading to protein aggregation in myosin storage myopathy and to evaluate the impact of these mutations on myosin assembly and muscle function, we expressed mutated myosin proteins in cultured human muscle cells and in the nematode Caenorhabditis elegans. While L1793P mutant myosin protein efficiently incorporated into the sarcomeric thick filaments, R1845W and H1901L mutants were prone to formation of myosin aggregates without assembly into striated sarcomeric thick filaments in cultured muscle cells. In C. elegans, mutant alleles of the myosin heavy chain gene unc-54 corresponding to R1845W, E1883K and H1901L, were as effective as the wild-type myosin gene in rescuing the null mutant worms, indicating that they retain functionality. Taken together, our results suggest that the basis for the pathogenic effect of the R1845W and H1901L mutations are primarily structural rather than functional. Further analyses are needed to identify the primary trigger for the histological changes seen in muscle biopsies of patients with L1793P and E1883K mutations.
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55
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Laing distal myopathy with a novel mutation in exon 34 of the MYH7 gene. Neuromuscul Disord 2016; 26:598-603. [DOI: 10.1016/j.nmd.2016.06.458] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 06/19/2016] [Accepted: 06/20/2016] [Indexed: 12/12/2022]
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Fiorillo C, Astrea G, Savarese M, Cassandrini D, Brisca G, Trucco F, Pedemonte M, Trovato R, Ruggiero L, Vercelli L, D'Amico A, Tasca G, Pane M, Fanin M, Bello L, Broda P, Musumeci O, Rodolico C, Messina S, Vita GL, Sframeli M, Gibertini S, Morandi L, Mora M, Maggi L, Petrucci A, Massa R, Grandis M, Toscano A, Pegoraro E, Mercuri E, Bertini E, Mongini T, Santoro L, Nigro V, Minetti C, Santorelli FM, Bruno C. MYH7-related myopathies: clinical, histopathological and imaging findings in a cohort of Italian patients. Orphanet J Rare Dis 2016; 11:91. [PMID: 27387980 PMCID: PMC4936326 DOI: 10.1186/s13023-016-0476-1] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 06/22/2016] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Myosin heavy chain 7 (MYH7)-related myopathies are emerging as an important group of muscle diseases of childhood and adulthood, with variable clinical and histopathological expression depending on the type and location of the mutation. Mutations in the head and neck domains are a well-established cause of hypertrophic cardiomyopathy whereas mutation in the distal regions have been associated with a range of skeletal myopathies with or without cardiac involvement, including Laing distal myopathy and Myosin storage myopathy. Recently the spectrum of clinical phenotypes associated with mutations in MYH7 has increased, blurring this scheme and adding further phenotypes to the list. A broader disease spectrum could lead to misdiagnosis of different congenital myopathies, neurogenic atrophy and other neuromuscular conditions. RESULTS As a result of a multicenter Italian study we collected clinical, histopathological and imaging data from a population of 21 cases from 15 families, carrying reported or novel mutations in MYH7. Patients displayed a variable phenotype including atypical pictures, as dropped head and bent spine, which cannot be classified in previously described groups. Half of the patients showed congenital or early infantile weakness with predominant distal weakness. Conversely, patients with later onset present prevalent proximal weakness. Seven patients were also affected by cardiomyopathy mostly in the form of non-compacted left ventricle. Muscle biopsy was consistent with minicores myopathy in numerous cases. Muscle MRI was meaningful in delineating a shared pattern of selective involvement of tibialis anterior muscles, with relative sparing of quadriceps. CONCLUSION This work adds to the genotype-phenotype correlation of MYH7-relatedmyopathies confirming the complexity of the disorder.
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Affiliation(s)
- C Fiorillo
- IRCCS Stella Maris, Molecular Medicine and Neuromuscular Disorders, Via dei Giacinti 2, 56128, Calambrone, Pisa, Italy. .,Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternad and Child Health, University of Genova, University of Genoa, Genoa, Italy.
| | - G Astrea
- IRCCS Stella Maris, Molecular Medicine and Neuromuscular Disorders, Via dei Giacinti 2, 56128, Calambrone, Pisa, Italy
| | - M Savarese
- Telethon Institute of Genetics and Medicine, Naples, Italy
| | - D Cassandrini
- IRCCS Stella Maris, Molecular Medicine and Neuromuscular Disorders, Via dei Giacinti 2, 56128, Calambrone, Pisa, Italy
| | - G Brisca
- Unit of Pediatric Neurology and Muscular Disorders, Istituto G.Gaslini, Genoa, Italy.,Department of Neuroscience, Center of Myology and Neurodegenerative Disorders, Istituto Giannina Gaslini, Genoa, Italy
| | - F Trucco
- Unit of Pediatric Neurology and Muscular Disorders, Istituto G.Gaslini, Genoa, Italy
| | - M Pedemonte
- Unit of Pediatric Neurology and Muscular Disorders, Istituto G.Gaslini, Genoa, Italy
| | - R Trovato
- IRCCS Stella Maris, Molecular Medicine and Neuromuscular Disorders, Via dei Giacinti 2, 56128, Calambrone, Pisa, Italy
| | - L Ruggiero
- Department of Neurosciences and Reproductive and Odontostomatologic Sciences, University Federico II, Naples, Italy
| | - L Vercelli
- Department of Neurosciences "Rita Levi Montalcini", University of Turin, Turin, Italy
| | - A D'Amico
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, IRCCS Bambino Gesù Children's Hospital, Rome, Italy
| | - G Tasca
- Don Carlo Gnocchi ONLUS Foundation, Rome, Italy
| | - M Pane
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | - M Fanin
- Department of Neurosciences, University of Padua, Padua, Italy
| | - L Bello
- Department of Neurosciences, University of Padua, Padua, Italy
| | - P Broda
- Unit of Pediatric Neurology and Muscular Disorders, Istituto G.Gaslini, Genoa, Italy
| | - O Musumeci
- Department of Clinical and Experimental Medicine and Nemo Sud Clinical Centre, University of Messina, Messina, Italy
| | - C Rodolico
- Department of Clinical and Experimental Medicine and Nemo Sud Clinical Centre, University of Messina, Messina, Italy
| | - S Messina
- Department of Clinical and Experimental Medicine and Nemo Sud Clinical Centre, University of Messina, Messina, Italy
| | - G L Vita
- Department of Clinical and Experimental Medicine and Nemo Sud Clinical Centre, University of Messina, Messina, Italy
| | - M Sframeli
- Department of Clinical and Experimental Medicine and Nemo Sud Clinical Centre, University of Messina, Messina, Italy
| | - S Gibertini
- Neuromuscular Diseases and Neuroimmunology Unit, IRCCS Foundation C Besta Neurological Institute, Milan, Italy
| | - L Morandi
- Neuromuscular Diseases and Neuroimmunology Unit, IRCCS Foundation C Besta Neurological Institute, Milan, Italy
| | - M Mora
- Neuromuscular Diseases and Neuroimmunology Unit, IRCCS Foundation C Besta Neurological Institute, Milan, Italy
| | - L Maggi
- Neuromuscular Diseases and Neuroimmunology Unit, IRCCS Foundation C Besta Neurological Institute, Milan, Italy
| | - A Petrucci
- Center for Neuromuscular and Neurological Rare Diseases, S. Camillo-Forlanini Hospital, Rome, Italy
| | - R Massa
- Department of Systems Medicine (Neurology), University of Tor Vergata, Rome, Italy
| | - M Grandis
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternad and Child Health, University of Genova, University of Genoa, Genoa, Italy
| | - A Toscano
- Department of Clinical and Experimental Medicine and Nemo Sud Clinical Centre, University of Messina, Messina, Italy
| | - E Pegoraro
- Department of Neurosciences, University of Padua, Padua, Italy
| | - E Mercuri
- Department of Paediatric Neurology, Catholic University, Rome, Italy
| | - E Bertini
- Unit of Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, IRCCS Bambino Gesù Children's Hospital, Rome, Italy
| | - T Mongini
- Department of Neurosciences "Rita Levi Montalcini", University of Turin, Turin, Italy
| | - L Santoro
- Department of Neurosciences and Reproductive and Odontostomatologic Sciences, University Federico II, Naples, Italy
| | - V Nigro
- Telethon Institute of Genetics and Medicine, Naples, Italy
| | - C Minetti
- Unit of Pediatric Neurology and Muscular Disorders, Istituto G.Gaslini, Genoa, Italy.,Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternad and Child Health, University of Genova, University of Genoa, Genoa, Italy
| | - F M Santorelli
- IRCCS Stella Maris, Molecular Medicine and Neuromuscular Disorders, Via dei Giacinti 2, 56128, Calambrone, Pisa, Italy
| | - C Bruno
- Department of Neuroscience, Center of Myology and Neurodegenerative Disorders, Istituto Giannina Gaslini, Genoa, Italy
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Brand P, Dyck PJB, Liu J, Berini S, Selcen D, Milone M. Distal myopathy with coexisting heterozygous TIA1 and MYH7 Variants. Neuromuscul Disord 2016; 26:511-5. [PMID: 27282841 DOI: 10.1016/j.nmd.2016.05.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 04/28/2016] [Accepted: 05/19/2016] [Indexed: 01/20/2023]
Abstract
TIA1 mutations cause Welander distal myopathy. MYH7 mutations result in various clinical phenotypes, including Laing distal myopathy and cardiomyopathy. We describe a family with coexisting TIA1 and MYH7 variants. The proband is a 67-year-old woman with easy tripping since childhood and progressive asymmetric distal limb weakness, but no cardiac involvement. Muscle biopsy showed rare rimmed vacuoles, minicore-like structures and congophilic inclusions. Her 66-year-old sister has a mild distal myopathy, supraventricular tachycardia and hypertrophic cardiomyopathy. Both sisters carry the only known pathogenic TIA1 mutation and a heterozygous MYH7 variant (c.5459G > A; p.Arg1820Gln). Another sibling with isolated distal myopathy carries only the TIA1 mutation. MYH7 p.Arg1820Gln involves a highly conserved residue and is predicted to be deleterious. Furthermore, the proband's childhood-onset distal leg weakness and sister's cardiomyopathy suggest that MYH7 p.Arg1820Gln likely affects function, favoring a digenic etiology of the myopathy.
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Affiliation(s)
- Patricio Brand
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - P James B Dyck
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Jie Liu
- PreventionGenetics, 3800 S. Business Park Ave, Marshfield, Wisconsin 54449, USA; Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Sarah Berini
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Duygu Selcen
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
| | - Margherita Milone
- Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
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Chanson JB, Lannes B, Echaniz-Laguna A. Is deltoid muscle biopsy useful in isolated camptocormia? A prospective study. Eur J Neurol 2016; 23:1086-92. [DOI: 10.1111/ene.12989] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 02/02/2016] [Indexed: 12/18/2022]
Affiliation(s)
- J.-B. Chanson
- Département de Neurologie; Hôpitaux Universitaires de Strasbourg; Strasbourg France
- Centre de Référence Neuromusculaire du Grand Est (CERNEST); Hôpitaux Universitaires de Strasbourg; Strasbourg France
| | - B. Lannes
- Centre de Référence Neuromusculaire du Grand Est (CERNEST); Hôpitaux Universitaires de Strasbourg; Strasbourg France
- Département de Pathologie; Hôpitaux Universitaires de Strasbourg; Strasbourg France
| | - A. Echaniz-Laguna
- Département de Neurologie; Hôpitaux Universitaires de Strasbourg; Strasbourg France
- Centre de Référence Neuromusculaire du Grand Est (CERNEST); Hôpitaux Universitaires de Strasbourg; Strasbourg France
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Evilä A, Arumilli M, Udd B, Hackman P. Targeted next-generation sequencing assay for detection of mutations in primary myopathies. Neuromuscul Disord 2016; 26:7-15. [DOI: 10.1016/j.nmd.2015.10.003] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/21/2015] [Accepted: 10/06/2015] [Indexed: 12/14/2022]
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60
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Gómez J, Reguero JR, Coto E. Luces y sombras en el diagnóstico genético de la miocardiopatía hipertrófica. Rev Esp Cardiol 2016. [DOI: 10.1016/j.recesp.2015.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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61
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Park HJ, Hong YB, Choi YC, Lee J, Kim EJ, Lee JS, Mo WM, Ki SM, Kim HI, Kim HJ, Hyun YS, Hong HD, Nam K, Jung SC, Kim SB, Kim SH, Kim DH, Oh KW, Kim SH, Yoo JH, Lee JE, Chung KW, Choi BO. ADSSL1 mutation relevant to autosomal recessive adolescent onset distal myopathy. Ann Neurol 2015; 79:231-43. [PMID: 26506222 DOI: 10.1002/ana.24550] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 10/07/2015] [Accepted: 10/18/2015] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Distal myopathy is a heterogeneous group of muscle diseases characterized by predominant distal muscle weakness. A study was done to identify the underlying cause of autosomal recessive adolescent onset distal myopathy. METHODS Four patients from 2 unrelated Korean families were evaluated. To isolate the genetic cause, exome sequencing was performed. In vitro and in vivo assays using myoblast cells and zebrafish models were performed to examine the ADSSL1 mutation causing myopathy pathogenesis. RESULTS Patients had an adolescent onset distal myopathy phenotype that included distal dominant weakness, facial muscle weakness, rimmed vacuoles, and mild elevation of serum creatine kinase. Exome sequencing identified completely cosegregating compound heterozygous mutations (p.D304N and p.I350fs) in ADSSL1, which encodes a muscle-specific adenylosuccinate synthase in both families. None of the controls had both mutations, and the mutation sites were located in well-conserved regions. Both the D304N and I350fs mutations in ADSSL1 led to decreased enzymatic activity. The knockdown of the Adssl1 gene significantly inhibited the proliferation of mouse myoblast cells, and the addition of human wild-type ADSSL1 reversed the reduced viability. In an adssl1 knockdown zebrafish model, muscle fibers were severely disrupted, which was evaluated by myosin expression and birefringence. In these conditions, supplementing wild-type ADSSL1 protein reversed the muscle defect. INTERPRETATION We suggest that mutations in ADSSL1 are the novel genetic cause of the autosomal recessive adolescent onset distal myopathy. This study broadens the genetic and clinical spectrum of distal myopathy and will be useful for exact molecular diagnostics.
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Affiliation(s)
- Hyung Jun Park
- Department of Neurology, Mokdong Hospital, Ewha Womans University School of Medicine, Seoul, South Korea.,Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea
| | - Young Bin Hong
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Young-Chul Choi
- Department of Neurology, Yonsei University College of Medicine, Seoul, South Korea
| | - Jinho Lee
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Eun Ja Kim
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Ji-Su Lee
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, South Korea
| | - Won Min Mo
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
| | - Soo Mi Ki
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, South Korea
| | - Hyo In Kim
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, South Korea
| | - Hye Jin Kim
- Department of Biological Science, Kongju National University, Gongju, South Korea
| | - Young Se Hyun
- Department of Biological Science, Kongju National University, Gongju, South Korea
| | - Hyun Dae Hong
- Department of Biological Science, Kongju National University, Gongju, South Korea
| | - Kisoo Nam
- Department of Chemistry, New York University, New York, NY
| | - Sung Chul Jung
- Department of Biochemistry, Ewha Womans University School of Medicine, Seoul, South Korea
| | - Sang-Beom Kim
- Department of Neurology, Kyung Hee University College of Medicine, Kangdong Hospital, Seoul, South Korea
| | - Se Hoon Kim
- Department of Pathology, Yonsei University College of Medicine, Seoul, South Korea
| | - Deok-Ho Kim
- Department of Bioengineering, University of Washington, Seattle, WA
| | - Ki-Wook Oh
- Department of Neurology, College of Medicine, Hanyang University, Seoul, South Korea
| | - Seung Hyun Kim
- Department of Neurology, College of Medicine, Hanyang University, Seoul, South Korea
| | - Jeong Hyun Yoo
- Department of Radiology, Mokdong Hospital, Ewha Womans University School of Medicine, Seoul, South Korea
| | - Ji Eun Lee
- Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, South Korea.,Samsung Genome Institute, Samsung Medical Center, Seoul, South Korea
| | - Ki Wha Chung
- Department of Biological Science, Kongju National University, Gongju, South Korea
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.,Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul, South Korea.,Neuroscience Center, Samsung Medical Center, Seoul, South Korea
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62
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Gómez J, Reguero JR, Coto E. The Ups and Downs of Genetic Diagnosis of Hypertrophic Cardiomyopathy. ACTA ACUST UNITED AC 2015; 69:61-8. [PMID: 26654849 DOI: 10.1016/j.rec.2015.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/07/2015] [Indexed: 01/16/2023]
Abstract
Massive DNA sequencing, also known as next-generation sequencing, has revolutionized genetic diagnosis. This technology has reduced the effort and cost needed to analyze several genes simultaneously and has made genetic evaluation available to a larger number of patients. In hypertrophic cardiomyopathy, genetic analysis has increased from the 3 main genes implicated in the disease (MYH7, MYBPC3, TNNT2) to sequencing of more than 20 related genes. Despite the advantages of acquiring this additional information, many patients show variants of uncertain significance (mainly amino acid changes), which may also be present in at least 1 healthy control undergoing genome sequencing. This will be a dead-end situation unless the variant can be demonstrated to be associated with the disease in the patient's family. In the absence of clear evidence that these variants are truly pathogenic, they cannot be used for reliable genetic counselling in family members. Massive sequencing also enables identification of new candidate genes, but again, the problem of variants of uncertain significance limits the success of these assessments.
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Affiliation(s)
- Juan Gómez
- Genética Molecular-Laboratorio de Medicina, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain
| | - Julián R Reguero
- Cardiología-Fundación Asturcor, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain
| | - Eliecer Coto
- Genética Molecular-Laboratorio de Medicina, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain; Departamento de Medicina, Universidad de Oviedo, Oviedo, Asturias, Spain.
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63
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Two families with MYH7 distal myopathy associated with cardiomyopathy and core formations. J Clin Neuromuscul Dis 2015; 16:164-9. [PMID: 25695922 DOI: 10.1097/cnd.0000000000000069] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Laing distal myopathy is caused by MYH7 gene mutations. Multiple families have been reported with varying patterns of skeletal and cardiac involvement as well as histopathological findings. CASE SERIES We report 2 families with p.Glu1508del mutation with detailed electrophysiological and muscle pathology findings. RESULTS All patients displayed the classic phenotype with weakness starting in the anterior compartment of the legs with a "hanging great toe." It was followed by finger extensors involvement, relatively sparing the extensor indicis proprius, giving the appearance of a "pointing index" finger. All the affected individuals had a dilated cardiomyopathy and core formations on muscle biopsy. Unexpectedly, neurogenic changes were also observed in some individuals. Both families were initially misdiagnosed with either central core disease or hereditary neuropathy. CONCLUSIONS Recognizing the classic phenotype, screening for cardiac involvement that may be clinically silent, and determining the mode of inheritance help with selecting the appropriate genetic test.
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64
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Malfatti E, Monges S, Lehtokari VL, Schaeffer U, Abath Neto O, Kiiski K, Lubieniecki F, Taratuto AL, Wallgren-Pettersson C, Laporte J, Romero NB. Bilateral foot-drop as predominant symptom in nebulin (NEB) gene related “core-rod” congenital myopathy. Eur J Med Genet 2015; 58:556-61. [DOI: 10.1016/j.ejmg.2015.09.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/10/2015] [Accepted: 09/21/2015] [Indexed: 12/11/2022]
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65
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Differential isoform expression and selective muscle involvement in muscular dystrophies. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:2833-42. [PMID: 26269091 DOI: 10.1016/j.ajpath.2015.06.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 06/18/2015] [Accepted: 06/22/2015] [Indexed: 12/23/2022]
Abstract
Despite the expression of the mutated gene in all muscles, selective muscles are involved in genetic muscular dystrophies. Different muscular dystrophies show characteristic patterns of fatty degenerative changes by muscle imaging, even to the extent that the patterns have been used for diagnostic purposes. However, the underlying molecular mechanisms explaining the selective involvement of muscles are not known. To test the hypothesis that different muscles may express variable amounts of different isoforms of muscle genes, we applied a custom-designed exon microarray containing probes for 57 muscle-specific genes to assay the transcriptional profiles in sets of human adult lower limb skeletal muscles. Quantitative real-time PCR and whole transcriptome sequencing were used to further analyze the results. Our results demonstrate significant variations in isoform and gene expression levels in anatomically different muscles. Comparison of the known patterns of selective involvement of certain muscles in two autosomal dominant titinopathies and one autosomal dominant myosinopathy, with the isoform and gene expression results, shows a correlation between the specific muscles involved and significant differences in the level of expression of the affected gene and exons in these same muscles compared with some other selected muscles. Our results suggest that differential expression levels of muscle genes and isoforms are one determinant in the selectivity of muscle involvement in muscular dystrophies.
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66
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A de novo mutation of the MYH7 gene in a large Chinese family with autosomal dominant myopathy. Hum Genome Var 2015; 2:15022. [PMID: 27081534 PMCID: PMC4785580 DOI: 10.1038/hgv.2015.22] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 04/24/2015] [Accepted: 05/11/2015] [Indexed: 02/07/2023] Open
Abstract
Laing distal myopathy (LDM) is an autosomal dominant myopathy that is caused by mutations in the slow/beta cardiac myosin heavy-chain (MYH7) gene. It has been recently reported that LDM presents with a wide range of clinical manifestations. We herein report a large Chinese family with autosomal dominant myopathy. The affected individuals in the family presented with foot drop in early childhood, along with progressive distal and proximal limb weakness. Their characteristic symptoms include scapular winging and scoliosis in the early disease phase and impairment of ambulation in the advanced phase. Although limb-girdle muscle dystrophy (LGMD) was suspected initially, a definite diagnosis could not be reached. As such, we performed linkage analysis and detected four linkage regions, namely 1q23.2-24.1, 14q11.2-12, 15q26.2-26.3 and 17q24.3. Through subsequent whole exome sequencing, we found a de novo p.K1617del causative mutation in the MYH7 gene and diagnosed the disease as LDM. This is the first LDM case in China. Our patients have severe clinical manifestations that mimic LGMD in comparison with the patients with the same mutation reported elsewhere.
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67
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Reis GF, de la Motte G, Gooding R, Laing NG, Margeta M. Complex sarcolemmal invaginations mimicking myotendinous junctions in a case of Laing early-onset distal myopathy. Neuropathology 2015; 35:575-81. [DOI: 10.1111/neup.12220] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 04/20/2015] [Accepted: 04/21/2015] [Indexed: 02/01/2023]
Affiliation(s)
- Gerald F. Reis
- Department of Pathology; University of California; San Francisco CA USA
| | | | - Rebecca Gooding
- Neurogenetics Unit, PathWest Laboratory Medicine; QEII Medical Centre; Nedlands WA Australia
| | - Nigel G. Laing
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, QEII Medical Centre; Nedlands WA Australia
| | - Marta Margeta
- Department of Pathology; University of California; San Francisco CA USA
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68
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The sarcomeric M-region: a molecular command center for diverse cellular processes. BIOMED RESEARCH INTERNATIONAL 2015; 2015:714197. [PMID: 25961035 PMCID: PMC4413555 DOI: 10.1155/2015/714197] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/08/2015] [Indexed: 02/07/2023]
Abstract
The sarcomeric M-region anchors thick filaments and withstands the mechanical stress of contractions by deformation, thus enabling distribution of physiological forces along the length of thick filaments. While the role of the M-region in supporting myofibrillar structure and contractility is well established, its role in mediating additional cellular processes has only recently started to emerge. As such, M-region is the hub of key protein players contributing to cytoskeletal remodeling, signal transduction, mechanosensing, metabolism, and proteasomal degradation. Mutations in genes encoding M-region related proteins lead to development of severe and lethal cardiac and skeletal myopathies affecting mankind. Herein, we describe the main cellular processes taking place at the M-region, other than thick filament assembly, and discuss human myopathies associated with mutant or truncated M-region proteins.
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69
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Alazami AM, Kentab AY, Faqeih E, Mohamed JY, Alkhalidi H, Hijazi H, Alkuraya FS. A novel syndrome of Klippel-Feil anomaly, myopathy, and characteristic facies is linked to a null mutation in MYO18B. J Med Genet 2015; 52:400-4. [PMID: 25748484 DOI: 10.1136/jmedgenet-2014-102964] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 02/15/2015] [Indexed: 11/03/2022]
Abstract
BACKGROUND Klippel-Feil anomaly (KFA) can be seen in a number of syndromes. We describe an apparently novel syndromic association with KFA. METHODS Clinical phenotyping of two consanguineous families followed by combined autozygome/exome analysis. RESULTS Two patients from two apparently unrelated families shared a strikingly similar phenotype characterised by KFA, myopathy, mild short stature, microcephaly, and distinctive facies. They shared a single founder autozygous interval in which whole exome sequencing revealed a truncating mutation in MYO18B. There was virtually complete loss of the transcript in peripheral blood, indicative of nonsense-mediated decay. Electron microscopy of muscle confirms abnormal myosin filaments with accompanying myopathic changes. CONCLUSIONS Deficiency of MYO18B is linked to a novel developmental disorder which combines KFA with myopathy. This suggests a widespread developmental role for this gene in humans, as observed for its murine ortholog.
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Affiliation(s)
- Anas M Alazami
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Amal Y Kentab
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Eissa Faqeih
- Department of Pediatric SubSpecialty, Children's Specialized Hospital, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Jawahir Y Mohamed
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Hisham Alkhalidi
- Department of Pathology, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Hadia Hijazi
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
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70
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A rare mutation in MYH7 gene occurs with overlapping phenotype. Biochem Biophys Res Commun 2015; 457:262-6. [PMID: 25576864 DOI: 10.1016/j.bbrc.2014.12.098] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 12/22/2014] [Indexed: 01/22/2023]
Abstract
Mutations in the beta-myosin heavy chain gene (MYH7) cause different muscle disorders. The specific molecular pathobiological processes that cause these different phenotypes remains unexplained. We describe three members of a family with an autosomal dominant mutation in the distal rod of MYH7 [c.5401G> A (p.Glu1801Lys)] displaying a complex phenotype characterized by Laing Distal Myopathy like phenotype, left ventricular non compaction cardiomyopathy and Fiber Type Disproportion picture at muscle biopsy. We suggest that this overlapping presentation confirm the phenotypic variability of MYH7 myopathy and may be helpful to improve the genotype phenotype correlation.
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71
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Laing early-onset distal myopathy in a Belgian family. Acta Neurol Belg 2014; 114:253-6. [PMID: 24710723 DOI: 10.1007/s13760-014-0298-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 03/24/2014] [Indexed: 10/25/2022]
Abstract
We report the first Belgian family with Laing early-onset distal myopathy (MPD1). The proposita started limping at age 7. Later, there was severe weakness of proximal and distal muscles, including neck flexors. Her daughter developed foot drop at age 4. Progressive weakness of distal limb extensor muscles and mild weakness of the neck flexor and proximal muscles were noted. In both patients, CK and nerve conductions were normal, but EMG showed a brief, small amplitude, abundant, polyphasic potential pattern. Heart and respiration were normal. Several muscle biopsies have been performed in each with various diagnoses, including aspecific myopathic changes, congenital fibre type disproportion, and denervation-reinnervation. Analysis of MYH7 revealed a c.4522_4524del mutation (p.Glu1508del). This appears to be a de novo mutation, which has been reported in French, Norwegian, and Finnish patients.
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72
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Roda RH, Schindler AB, Blackstone C, Mammen AL, Corse AM, Lloyd TE. Laing distal myopathy pathologically resembling inclusion body myositis. Ann Clin Transl Neurol 2014; 1:1053-8. [PMID: 25574480 PMCID: PMC4284131 DOI: 10.1002/acn3.140] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 10/13/2014] [Accepted: 10/14/2014] [Indexed: 11/18/2022] Open
Abstract
Mutations in MYH7 cause autosomal dominant Laing distal myopathy. We present a family with a previously reported deletion (c.5186_5188delAGA, p.K1729del). Muscle pathology in one family member was characterized by an inflammatory myopathy with rimmed vacuoles, increased MHC Class I expression, and perivascular and endomysial muscle inflammation comprising CD3+, CD4+, CD8+, and CD68+ inflammatory cells. Interestingly, this biopsy specimen contained TDP-43, p62, and SMI-31-positive protein aggregates typical of inclusion body myositis. These findings should alert physicians to the possibility that patients with MYH7 mutations may have muscle biopsies showing pathologic findings similar to inclusion body myositis.
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Affiliation(s)
- Ricardo H Roda
- Neuromuscular Disorders and Neurogenetics Divisions, Department of Neurology, New York University Langone Medical Center New York, New York ; Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, Maryland
| | - Alice B Schindler
- Hereditary Neurological Diseases Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, Maryland
| | - Craig Blackstone
- Cell Biology Section, Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health Bethesda, Maryland
| | - Andrew L Mammen
- Department of Neurology, Johns Hopkins University School of Medicine Baltimore, Maryland ; Department of Medicine, Johns Hopkins University School of Medicine Baltimore, Maryland ; Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulation, National Institutes of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health Bethesda, Maryland
| | - Andrea M Corse
- Department of Neurology, Johns Hopkins University School of Medicine Baltimore, Maryland
| | - Thomas E Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine Baltimore, Maryland ; Department of Neuroscience, Johns Hopkins University School of Medicine Baltimore, Maryland
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73
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Valdés-Mas R, Gutiérrez-Fernández A, Gómez J, Coto E, Astudillo A, Puente DA, Reguero JR, Álvarez V, Morís C, León D, Martín M, Puente XS, López-Otín C. Mutations in filamin C cause a new form of familial hypertrophic cardiomyopathy. Nat Commun 2014; 5:5326. [PMID: 25351925 DOI: 10.1038/ncomms6326] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 09/19/2014] [Indexed: 01/21/2023] Open
Abstract
Mutations in different genes encoding sarcomeric proteins are responsible for 50-60% of familial cases of hypertrophic cardiomyopathy (HCM); however, the genetic alterations causing the disease in one-third of patients are currently unknown. Here we describe a case with familial HCM of unknown cause. Whole-exome sequencing reveals a variant in the gene encoding the sarcomeric protein filamin C (p.A1539T) that segregates with the disease in this family. Sequencing of 92 HCM cases identifies seven additional variants segregating with the disease in eight families. Patients with FLNC mutations show marked sarcomeric abnormalities in cardiac muscle, and functional analysis reveals that expression of these FLNC variants resulted in the formation of large filamin C aggregates. Clinical studies indicate that FLNC-mutated patients have higher incidence of sudden cardiac death. On the basis of these findings, we conclude that mutations in the gene encoding the sarcomeric protein filamin C cause a new form of familial HMC.
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Affiliation(s)
- Rafael Valdés-Mas
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Ana Gutiérrez-Fernández
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Juan Gómez
- Genética Molecular, Red de Investigación Renal (REDINREN), 33006 Oviedo, Spain
| | - Eliecer Coto
- 1] Genética Molecular, Red de Investigación Renal (REDINREN), 33006 Oviedo, Spain [2] Departamento de Medicina, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Aurora Astudillo
- Servicio de Anatomía Patológica, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Diana A Puente
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Julián R Reguero
- Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Victoria Álvarez
- Genética Molecular, Red de Investigación Renal (REDINREN), 33006 Oviedo, Spain
| | - César Morís
- 1] Departamento de Medicina, Universidad de Oviedo, 33006 Oviedo, Spain [2] Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Diego León
- Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - María Martín
- Servicio de Cardiología, Fundación Asturcor, Hospital Universitario Central de Asturias, 33006 Oviedo, Spain
| | - Xose S Puente
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
| | - Carlos López-Otín
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Instituto Universitario de Oncología-IUOPA, Universidad de Oviedo, 33006 Oviedo, Spain
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Abstract
In this article, distal myopathy syndromes are discussed. A discussion of the more traditional distal myopathies is followed by discussion of the myofibrillar myopathies. Other clinically and genetically distinctive distal myopathy syndromes usually based on single or smaller family cohorts are reviewed. Other neuromuscular disorders that are important to recognize are also considered, because they show prominent distal limb weakness.
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Affiliation(s)
- Mazen M Dimachkie
- Neuromuscular Section, Neurophysiology Division, Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA.
| | - Richard J Barohn
- Department of Neurology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Mail Stop 2012, Kansas City, KS 66160, USA
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75
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Finsterer J, Brandau O, Stöllberger C, Wallefeld W, Laing NG, Laccone F. Distal myosin heavy chain-7 myopathy due to the novel transition c.5566G>A (p.E1856K) with high interfamilial cardiac variability and putative anticipation. Neuromuscul Disord 2014; 24:721-5. [PMID: 24953931 DOI: 10.1016/j.nmd.2014.05.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 05/17/2014] [Accepted: 05/21/2014] [Indexed: 11/25/2022]
Abstract
Myosin-heavy-chain 7 (MYH7)-myopathy manifests clinically with a distal, scapuloperoneal, limb-girdle (proximal), or axial distribution and may involve the respiratory muscles. Cardiac involvement is frequent, ranging from relaxation impairment to severe dilative cardiomyopathy. Progression and earlier onset of cardiac disease in successive generations with MYH7-myopathy is unreported. In a five-generation family MYH7-myopathy due to the novel c.5566G > A (p.E1856K) mutation manifested with late-onset, distal > proximal myopathy and variable degree of cardiac involvement. The index patient developed distal myopathy since age 49 y and anginal chest pain. Her mother had distal myopathy and impaired myocardial relaxation. The daughter of the index patient had discrete myopathy but left ventricular hypertrabeculation/noncompaction and ventricular arrhythmias requiring an implantable cardioverter defibrillator. The granddaughter of the index patient had infantile dilated cardiomyopathy without overt myopathy. Cardiac involvement may be present in MYH7-myopathy and may be progressive between the generations, ranging from relaxation abnormality to noncompaction, ventricular arrhythmias, and dilated cardiomyopathy.
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Affiliation(s)
| | - Oliver Brandau
- Institute of Medical Genetics, Medical University of Vienna, Währinger Strasse 10, 1090 Vienna, Austria
| | - Claudia Stöllberger
- 2nd Medical Department with Cardiology and Intensive Care Medicine Krankenanstalt Rudolfstiftung, Vienna, Austria
| | - William Wallefeld
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Nigel G Laing
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Franco Laccone
- Institute of Medical Genetics, Medical University of Vienna, Währinger Strasse 10, 1090 Vienna, Austria
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76
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Lamont PJ, Wallefeld W, Hilton-Jones D, Udd B, Argov Z, Barboi AC, Bonneman C, Boycott KM, Bushby K, Connolly AM, Davies N, Beggs AH, Cox GF, Dastgir J, DeChene ET, Gooding R, Jungbluth H, Muelas N, Palmio J, Penttilä S, Schmedding E, Suominen T, Straub V, Staples C, Van den Bergh PYK, Vilchez JJ, Wagner KR, Wheeler PG, Wraige E, Laing NG. Novel mutations widen the phenotypic spectrum of slow skeletal/β-cardiac myosin (MYH7) distal myopathy. Hum Mutat 2014; 35:868-79. [PMID: 24664454 DOI: 10.1002/humu.22553] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 03/10/2014] [Indexed: 01/01/2023]
Abstract
Laing early onset distal myopathy and myosin storage myopathy are caused by mutations of slow skeletal/β-cardiac myosin heavy chain encoded by the gene MYH7, as is a common form of familial hypertrophic/dilated cardiomyopathy. The mechanisms by which different phenotypes are produced by mutations in MYH7, even in the same region of the gene, are not known. To explore the clinical spectrum and pathobiology, we screened the MYH7 gene in 88 patients from 21 previously unpublished families presenting with distal or generalized skeletal muscle weakness, with or without cardiac involvement. Twelve novel mutations have been identified in thirteen families. In one of these families, the father of the proband was found to be a mosaic for the MYH7 mutation. In eight cases, de novo mutation appeared to have occurred, which was proven in four. The presenting complaint was footdrop, sometimes leading to delayed walking or tripping, in members of 17 families (81%), with other presentations including cardiomyopathy in infancy, generalized floppiness, and scoliosis. Cardiac involvement as well as skeletal muscle weakness was identified in nine of 21 families. Spinal involvement such as scoliosis or rigidity was identified in 12 (57%). This report widens the clinical and pathological phenotypes, and the genetics of MYH7 mutations leading to skeletal muscle diseases.
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Affiliation(s)
- Phillipa J Lamont
- Neurogenetic Unit, Department of Neurology, Royal Perth Hospital, Western Australia, Australia; Diagnostic Genomics Laboratory, Pathwest, Queen Elizabeth II Medical Centre, Nedlands, Western Australia, Australia
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77
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North KN, Wang CH, Clarke N, Jungbluth H, Vainzof M, Dowling JJ, Amburgey K, Quijano-Roy S, Beggs AH, Sewry C, Laing NG, Bönnemann CG. Approach to the diagnosis of congenital myopathies. Neuromuscul Disord 2014; 24:97-116. [PMID: 24456932 PMCID: PMC5257342 DOI: 10.1016/j.nmd.2013.11.003] [Citation(s) in RCA: 187] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/06/2013] [Accepted: 11/08/2013] [Indexed: 10/26/2022]
Abstract
Over the past decade there have been major advances in defining the genetic basis of the majority of congenital myopathy subtypes. However the relationship between each congenital myopathy, defined on histological grounds, and the genetic cause is complex. Many of the congenital myopathies are due to mutations in more than one gene, and mutations in the same gene can cause different muscle pathologies. The International Standard of Care Committee for Congenital Myopathies performed a literature review and consulted a group of experts in the field to develop a summary of (1) the key features common to all forms of congenital myopathy and (2) the specific features that help to discriminate between the different genetic subtypes. The consensus statement was refined by two rounds of on-line survey, and a three-day workshop. This consensus statement provides guidelines to the physician assessing the infant or child with hypotonia and weakness. We summarise the clinical features that are most suggestive of a congenital myopathy, the major differential diagnoses and the features on clinical examination, investigations, muscle pathology and muscle imaging that are suggestive of a specific genetic diagnosis to assist in prioritisation of genetic testing of known genes. As next generation sequencing becomes increasingly used as a diagnostic tool in clinical practise, these guidelines will assist in determining which sequence variations are likely to be pathogenic.
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Affiliation(s)
- Kathryn N North
- Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Road, Parkville, Melbourne, Victoria 3052, Australia; Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, University of Sydney, Sydney, Australia.
| | - Ching H Wang
- Driscoll Children's Hospital, Corpus Christi, TX, United States
| | - Nigel Clarke
- Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, University of Sydney, Sydney, Australia
| | - Heinz Jungbluth
- Evelina Children's Hospital, Department of Paediatric Neurology, London, United Kingdom; Randall Division for Cell and Molecular Biophysics, Muscle Signalling Section, King's College, London, United Kingdom; Clinical Neuroscience Division, IoP, London, United Kingdom
| | - Mariz Vainzof
- Human Genome Research Center, University of Sao Paulo, Sao Paulo, Brazil
| | - James J Dowling
- Division of Neurology, Department of Paediatrics, Hospital for Sick Children, Toronto, ON, Canada
| | - Kimberly Amburgey
- Division of Neurology, Department of Paediatrics, Hospital for Sick Children, Toronto, ON, Canada
| | - Susana Quijano-Roy
- Department of Pediatrics, Garches Neuromuscular Reference Center (GNMH), APHP Raymond Poincare University Hospital (UVSQ), Garches, France
| | - Alan H Beggs
- Children's Hospital Boston, Boston, MA, United States
| | - Caroline Sewry
- Dubowitz Neuromuscular Centre, London, United Kingdom; Wolfson Centre of Inherited Neuromuscular Diseases, RJAH Orthopaedic Hospital, Oswestry, United Kingdom
| | - Nigel G Laing
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, QQ Building, QEII Medical Centre, Nedlands, Western Australia 6009, Australia
| | - Carsten G Bönnemann
- Neuromuscular and Neurogenetic Disorders of Childhood Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD, United States
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78
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Exome sequencing identifies Laing distal myopathy MYH7 mutation in a Roma family previously diagnosed with distal neuronopathy. Neuromuscul Disord 2014; 24:156-61. [DOI: 10.1016/j.nmd.2013.10.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 10/08/2013] [Accepted: 10/31/2013] [Indexed: 11/22/2022]
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Recessive myosin myopathy with external ophthalmoplegia associated with MYH2 mutations. Eur J Hum Genet 2013; 22:801-8. [PMID: 24193343 DOI: 10.1038/ejhg.2013.250] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 08/28/2013] [Accepted: 10/01/2013] [Indexed: 11/08/2022] Open
Abstract
Myosin myopathies comprise a group of inherited diseases caused by mutations in myosin heavy chain (MyHC) genes. Homozygous or compound heterozygous truncating MYH2 mutations have been demonstrated to cause recessive myopathy with ophthalmoplegia, mild-to-moderate muscle weakness and complete lack of type 2A muscle fibers. In this study, we describe for the first time the clinical and morphological characteristics of recessive myosin IIa myopathy associated with MYH2 missense mutations. Seven patients of five different families with a myopathy characterized by ophthalmoplegia and mild-to-moderate muscle weakness were investigated. Muscle biopsy was performed to study morphological changes and MyHC isoform expression. Five of the patients were homozygous for MYH2 missense mutations, one patient was compound heterozygous for a missense and a nonsense mutation and one patient was homozygous for a frame-shift MYH2 mutation. Muscle biopsy demonstrated small or absent type 2A muscle fibers and reduced or absent expression of the corresponding MyHC IIa transcript and protein. We conclude that mild muscle weakness and ophthalmoplegia in combination with muscle biopsy demonstrating small or absent type 2A muscle fibers are the hallmark of recessive myopathy associated with MYH2 mutations.
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81
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Wolny M, Colegrave M, Colman L, White E, Knight PJ, Peckham M. Cardiomyopathy mutations in the tail of β-cardiac myosin modify the coiled-coil structure and affect integration into thick filaments in muscle sarcomeres in adult cardiomyocytes. J Biol Chem 2013; 288:31952-62. [PMID: 24047955 DOI: 10.1074/jbc.m113.513291] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
It is unclear why mutations in the filament-forming tail of myosin heavy chain (MHC) cause hypertrophic or dilated cardiomyopathy as these mutations should not directly affect contraction. To investigate this, we first investigated the impact of five hypertrophic cardiomyopathy-causing (N1327K, E1356K, R1382W, E1555K, and R1768K) and one dilated cardiomyopathy-causing (R1500W) tail mutations on their ability to incorporate into muscle sarcomeres in vivo. We used adenoviral delivery to express full-length wild type or mutant enhanced GFP-MHC in isolated adult cardiomyocytes. Three mutations (N1327K, E1356K, and E1555K) reduced enhanced GFP-MHC incorporation into muscle sarcomeres, whereas the remainder had no effect. No mutations significantly affected contraction. Fluorescence recovery after photobleaching showed that fluorescence recovery for the mutation that incorporated least well (N1327K) was significantly faster than that of WT with half-times of 25.1 ± 1.8 and 32.2 ± 2.5 min (mean ± S.E.), respectively. Next, we determined the effects of each mutation on the helical properties of wild type and seven mutant peptides (7, 11, or 15 heptads long) from the myosin tail by circular dichroism. R1382W and E1768K slightly increased the α-helical nature of peptides. The remaining mutations reduced α-helical content, with N1327K showing the greatest reduction. Only peptides containing residues 1301-1329 were highly α-helical suggesting that this region helps in initiation of coiled coil. These results suggest that small effects of mutations on helicity translate into a reduced ability to incorporate into sarcomeres, which may elicit compensatory hypertrophy.
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Affiliation(s)
- Marcin Wolny
- From the School of Molecular and Cellular Biology and
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82
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Abstract
The distal myopathies are a heterogeneous group of genetic disorders defined by a predominant distal weakness at onset or throughout the evolution of the disease and by pathological data supporting a myopathic process. The number of genes associated with distal myopathies continues to increase. Fourteen distinct distal myopathies are currently defined by their gene and causative mutations, compared to just five entities delineated on clinical grounds two decades ago. The known proteins affected in the distal myopathies are of many types and include a significant number of sarcomeric proteins. The useful indicators for clinicians to direct towards a correct molecular diagnosis are the mode of inheritance, the age at onset, the pattern of muscle involvement, the serum creatine kinase level and the muscle pathology findings. This review gives an overview of the clinical and genetic characteristics of the currently identified distal myopathies with emphasis on some recent findings.
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83
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Ceyhan-Birsoy O, Agrawal PB, Hidalgo C, Schmitz-Abe K, DeChene ET, Swanson LC, Soemedi R, Vasli N, Iannaccone ST, Shieh PB, Shur N, Dennison JM, Lawlor MW, Laporte J, Markianos K, Fairbrother WG, Granzier H, Beggs AH. Recessive truncating titin gene, TTN, mutations presenting as centronuclear myopathy. Neurology 2013; 81:1205-14. [PMID: 23975875 DOI: 10.1212/wnl.0b013e3182a6ca62] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
OBJECTIVE To identify causative genes for centronuclear myopathies (CNM), a heterogeneous group of rare inherited muscle disorders that often present in infancy or early life with weakness and hypotonia, using next-generation sequencing of whole exomes and genomes. METHODS Whole-exome or -genome sequencing was performed in a cohort of 29 unrelated patients with clinicopathologic diagnoses of CNM or related myopathy depleted for cases with mutations of MTM1, DNM2, and BIN1. Immunofluorescence analyses on muscle biopsies, splicing assays, and gel electrophoresis of patient muscle proteins were performed to determine the molecular consequences of mutations of interest. RESULTS Autosomal recessive compound heterozygous truncating mutations of the titin gene, TTN, were identified in 5 individuals. Biochemical analyses demonstrated increased titin degradation and truncated titin proteins in patient muscles, establishing the impact of the mutations. CONCLUSIONS Our study identifies truncating TTN mutations as a cause of congenital myopathy that is reported as CNM. Unlike the classic CNM genes that are all involved in excitation-contraction coupling at the triad, TTN encodes the giant sarcomeric protein titin, which forms a myofibrillar backbone for the components of the contractile machinery. This study expands the phenotypic spectrum associated with TTN mutations and indicates that TTN mutation analysis should be considered in cases of possible CNM without mutations in the classic CNM genes.
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Affiliation(s)
- Ozge Ceyhan-Birsoy
- From the Division of Genetics and Program in Genomics, The Manton Center for Orphan Disease Research (O.C.-B., P.B.A., K.S.-A., E.T.D., L.C.S., K.M., A.H.B.), and Division of Newborn Medicine (P.B.A.), Boston Children's Hospital, Harvard Medical School, Boston, MA; Department of Physiology and Sarver Molecular Cardiovascular Research Program (C.H., H.G.), University of Arizona, Tucson; Center for Computational Molecular Biology and Department of Molecular and Cellular Biology and Biochemistry (R.S., W.G.F.), Brown University, Providence, RI; Department of Translational Medicine (N.V., J.L.), IGBMC, INSERM U964, CNRS UMR7104, University of Strasbourg, Illkirch, France; Departments of Pediatrics and Neurology and Neurotherapeutics (S.T.I.), University of Texas Southwestern Medical Center, Dallas; Department of Neurology (P.B.S.), University of California, Los Angeles; Division of Human Genetics (N.S.), Department of Pediatrics, Rhode Island Hospital, Providence; Department of Pediatrics, Division of Pediatric Pathology (J.M.D.), and Department of Pathology and Laboratory Medicine (M.W.L), Medical College of Wisconsin, Milwaukee; Hasbro Children's Hospital (J.M.D.), and Center for Biomedical Engineering (W.G.F.), Brown University, Providence, RI
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84
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Distal myopathies: from clinical classification to molecular understanding. J Neural Transm (Vienna) 2013; 120 Suppl 1:S3-7. [PMID: 23842731 DOI: 10.1007/s00702-013-1058-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 06/19/2013] [Indexed: 10/26/2022]
Abstract
The distal myopathies are a group of rare diseases that in the past were primarily classified by eponyms. Classification criteria were the beginning of the disease, the distribution of the muscle weakness, the course of the disease, the prognosis, and histological changes in the muscle biopsy. Advances of molecular genetics have identified various genes and mutations in many of the clinical phenotypes. This led to modifications and extensions of the existing clinical classification. Our own study on 42 patients with distal myopathy including 15 patients from six families with matrin-3 mutation suggests that in distal myopathies (1) there seem to be no monogenetic classical phenotypes; (2) there are phenotypes with different genotypes and (3) phenotypes with genotypes that are usually associated with other than distal phenotypes. Some of these phenotypes could not be classified according to the traditional clinical classification. In matrin-3 associated myopathy most but not all patients had predominant distal weakness. Also in the initial families distal weakness myopathy was associated with vocal cord and pharyngeal weakness, this was observed in half of our patients. Three of 15 patients met the criteria of Welander-phenotype. The recent classification by Udd distinguishes major groups of myopathies based on age of onset, mode of inheritance, and morphological changes in muscle biopsy. In many but not all subforms of these major groups the genotype has been established so far.
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85
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Park JM, Kim YJ, Yoo JH, Hong YB, Park JH, Koo H, Chung KW, Choi BO. A novel MYH7 mutation with prominent paraspinal and proximal muscle involvement. Neuromuscul Disord 2013; 23:580-6. [PMID: 23707328 DOI: 10.1016/j.nmd.2013.04.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/20/2013] [Accepted: 04/22/2013] [Indexed: 12/12/2022]
Abstract
Laing distal myopathy (LDM) is caused by mutations in the MYH7 gene, and known to have muscle weakness of distal limbs and neck flexors. Through whole exome sequencing, we identified a novel p.Ala1439Pro MYH7 mutation in a Korean LDM family. This missense mutation is located in more N-terminal than any reported rod domain LDM mutations. In the early stage of disease, the present patients showed similar clinical patterns to the previously described patients of LDM. However, in the later stage, fatty replacement and atrophy of paraspinal or proximal leg muscles was more severely marked than lower leg muscles, and asymmetric atrophies were observed in trapezius, subscapularis and adductor magnus muscles. Distal myopathy like LDM showed marked and predominant fatty infiltrations in paraspinal or proximal leg muscles with marked asymmetry. These observations expand the clinical spectrum of LDM with the MYH7 mutation.
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Affiliation(s)
- Jin-Mo Park
- Department of Neurology, Ewha Womans University School of Medicine, Seoul, Republic of Korea
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86
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Roadmap to determine the point mutations involved in cardiomyopathy disorder: A Bayesian approach. Gene 2013; 519:34-40. [DOI: 10.1016/j.gene.2013.01.056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/31/2012] [Accepted: 01/27/2013] [Indexed: 11/18/2022]
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87
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Clarke NF, Amburgey K, Teener J, Camelo-Piragua S, Kesari A, Punetha J, Waddell LB, Davis M, Laing NG, Monnier N, North KN, Hoffman EP, Dowling JJ. A novel mutation expands the genetic and clinical spectrum of MYH7-related myopathies. Neuromuscul Disord 2013; 23:432-6. [PMID: 23478172 DOI: 10.1016/j.nmd.2013.02.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 02/08/2013] [Accepted: 02/12/2013] [Indexed: 01/16/2023]
Abstract
MYH7 mutations are an established cause of Laing distal myopathy, myosin storage myopathy, and cardiomyopathy, as well as additional myopathy subtypes. We report a novel MYH7 mutation (p.Leu1597Arg) that arose de novo in two unrelated probands. Proband 1 has a myopathy characterized by distal weakness and prominent contractures and histopathology typical of multi-minicore disease. Proband 2 has an axial myopathy and histopathology consistent with congenital fiber type disproportion. These cases highlight the broad spectrum of clinical and histological patterns associated with MYH7 mutations, and provide further evidence that MYH7 is likely responsible for a greater proportion of congenital myopathies than currently appreciated.
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Affiliation(s)
- Nigel F Clarke
- INMR, The Children's Hospital at Westmead & Discipline of Paediatrics and Child Health, University of Sydney, Sydney, Australia
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88
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Qaisar R, Renaud G, Hedstrom Y, Pöllänen E, Ronkainen P, Kaprio J, Alen M, Sipilä S, Artemenko K, Bergquist J, Kovanen V, Larsson L. Hormone replacement therapy improves contractile function and myonuclear organization of single muscle fibres from postmenopausal monozygotic female twin pairs. J Physiol 2013; 591:2333-44. [PMID: 23459759 DOI: 10.1113/jphysiol.2012.250092] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ageing is associated with a decline in muscle mass and strength leading to increased physical dependency in old age. Postmenopausal women experience a greater decline than men of similar age in parallel with the decrease in female sex steroid hormone production. We recruited six monozygous female twin pairs (55-59 years old) where only one twin pair was on hormone replacement therapy (HRT use = 7.8 ± 4.3 years) to investigate the association of HRT with the cytoplasmic volume supported by individual myonuclei (myonuclear domain (MND) size,) together with specific force at the single fibre level. HRT use was associated with a significantly smaller (∼27%; P < 0.05) mean MND size in muscle fibres expressing the type I but not the IIa myosin heavy chain (MyHC) isoform. In comparison to non-users, higher specific force was recorded in HRT users both in muscle fibres expressing type I (∼27%; P < 0.05) and type IIa (∼23%; P < 0.05) MyHC isoforms. These differences were fibre-type dependent, i.e. the higher specific force in fast-twitch muscle fibres was primarily caused by higher force per cross-bridge while slow-twitch fibres relied on both a higher number and force per cross-bridge. HRT use had no effect on fibre cross-sectional area (CSA), velocity of unloaded shortening (V0) and relative proportion of MyHC isoforms. In conclusion, HRT appears to have significant positive effects on both regulation of muscle contraction and myonuclei organization in postmenopausal women.
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Affiliation(s)
- Rizwan Qaisar
- Department of Neuroscience, Clinical Neurophysiology, Uppsala University, Sweden
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89
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Tajsharghi H, Oldfors A. Myosinopathies: pathology and mechanisms. Acta Neuropathol 2013; 125:3-18. [PMID: 22918376 PMCID: PMC3535372 DOI: 10.1007/s00401-012-1024-2] [Citation(s) in RCA: 129] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 06/27/2012] [Accepted: 07/19/2012] [Indexed: 11/24/2022]
Abstract
The myosin heavy chain (MyHC) is the molecular motor of muscle and forms the backbone of the sarcomere thick filaments. Different MyHC isoforms are of importance for the physiological properties of different muscle fiber types. Hereditary myosin myopathies have emerged as an important group of diseases with variable clinical and morphological expression depending on the mutated isoform and type and location of the mutation. Dominant mutations in developmental MyHC isoform genes (MYH3 and MYH8) are associated with distal arthrogryposis syndromes. Dominant or recessive mutations affecting the type IIa MyHC (MYH2) are associated with early-onset myopathies with variable muscle weakness and ophthalmoplegia as a consistent finding. Myopathies with scapuloperoneal, distal or limb-girdle muscle weakness including entities, such as myosin storage myopathy and Laing distal myopathy are the result of usually dominant mutations in the gene for slow/β cardiac MyHC (MYH7). Protein aggregation is part of the features in some of these myopathies. In myosin storage myopathy protein aggregates are formed by accumulation of myosin beneath the sarcolemma and between myofibrils. In vitro studies on the effects of different mutations associated with myosin storage myopathy and Laing distal myopathy indicate altered biochemical and biophysical properties of the light meromyosin, which is essential for thick filament assembly. Protein aggregates in the form of tubulofilamentous inclusions in association with vacuolated muscle fibers are present at late stage of dominant myosin IIa myopathy and sometimes in Laing distal myopathy. These protein aggregates exhibit features indicating defective degradation of misfolded proteins. In addition to protein aggregation and muscle fiber degeneration some of the myosin mutations cause functional impairment of the molecular motor adding to the pathogenesis of myosinopathies.
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Affiliation(s)
- Homa Tajsharghi
- Department of Pathology, Institute of Biomedicine, University of Gothenburg, Sahlgrenska University Hospital, 413 45 Gothenburg, Sweden
| | - Anders Oldfors
- Department of Pathology, Institute of Biomedicine, University of Gothenburg, Sahlgrenska University Hospital, 413 45 Gothenburg, Sweden
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90
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Abstract
Congenital myopathies are a heterogeneous group of inherited muscle disorders, characterized by the predominance of particular histopathological features on muscle biopsy, such as cores (central core disease) or rods (nemaline myopathy). Clinically, early onset of the disease, stable or slowly progressive muscle weakness, hypotonia and delayed motor development are common in most forms. As a result, the diagnosis of a subtype of congenital myopathy is largely based on the presence of specific structural abnormalities in the skeletal muscle detected by enzyme-histochemistry and electron microscopy studies. During the last decades there have been significant advances in the identification of the genetic basis of most congenital myopathies. However, there is significant genetic heterogeneity within the main groups of congenital myopathies, and mutations in one particular gene may also cause diverse clinical and morphological phenotypes. Thus, the nosography and nosology in this field is still evolving.
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Affiliation(s)
- Norma Beatriz Romero
- Morphology Neuromuscular Unit of the Myology Institute, GHU Pitié-Salpêtrière, Paris, France.
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91
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Murgiano L, Tammen I, Harlizius B, Drögemüller C. A de novo germline mutation in MYH7 causes a progressive dominant myopathy in pigs. BMC Genet 2012; 13:99. [PMID: 23153285 PMCID: PMC3542579 DOI: 10.1186/1471-2156-13-99] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 10/25/2012] [Indexed: 11/20/2022] Open
Abstract
Background About 9% of the offspring of a clinically healthy Piétrain boar named ‘Campus’ showed a progressive postural tremor called Campus syndrome (CPS). Extensive backcross experiments suggested a dominant mode of inheritance, and the founder boar was believed to be a gonadal mosaic. A genome-scan mapped the disease-causing mutation to an 8 cM region of porcine chromosome 7 containing the MHY7 gene. Human distal myopathy type 1 (MPD1), a disease partially resembling CPS in pigs, has been associated with mutations in the MYH7 gene. Results The porcine MYH7 gene structure was predicted based on porcine reference genome sequence, porcine mRNA, and in comparison to the human ortholog. The gene structure was highly conserved with the exception of the first exon. Mutation analysis of a contiguous genomic interval of more than 22 kb spanning the complete MYH7 gene revealed an in-frame insertion within exon 30 of MYH7 (c.4320_4321insCCCGCC) which was perfectly associated with the disease phenotype and confirmed the dominant inheritance. The mutation is predicted to insert two amino acids (p.Ala1440_Ala1441insProAla) in a very highly conserved region of the myosin tail. The boar ‘Campus’ was shown to be a germline and somatic mosaic as assessed by the presence of the mutant allele in seven different organs. Conclusion This study illustrates the usefulness of recently established genomic resources in pigs. We have identified a spontaneous mutation in MYH7 as the causative mutation for CPS. This paper describes the first case of a disorder caused by a naturally occurring mutation in the MYH7 gene of a non-human mammalian species. Our study confirms the previous classification as a primary myopathy and provides a defined large animal model for human MPD1. We provide evidence that the CPS mutation occurred during the early development of the boar ‘Campus’. Therefore, this study provides an example of germline mosaicism with an asymptomatic founder.
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Affiliation(s)
- Leonardo Murgiano
- Institute of Genetics, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, Bern, 3001, Switzerland
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92
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Abstract
Neuromuscular disorders affect the peripheral nervous system and muscle. The principle effect of neuromuscular disorders is therefore on the ability to perform voluntary movements. Neuromuscular disorders cause significant incapacity, including, at the most extreme, almost complete paralysis. Neuromuscular diseases include some of the most devastating disorders that afflict mankind, for example motor neuron disease. Neuromuscular diseases have onset any time from in utero until old age. They are most often genetic. The last 25 years has been the golden age of genetics, with the disease genes responsible for many genetic neuromuscular disorders now identified. Neuromuscular disorders may be inherited as autosomal dominant, autosomal recessive, or X-linked traits. They may also result from mutations in mitochondrial DNA or from de novo mutations not present in the peripheral blood DNA of either parent. The high incidence of de novo mutation has been one of the surprises of the recent increase in information about the genetics of neuromuscular disorders. The disease burden imposed on families is enormous including decision making in relation to presymptomatic diagnosis for late onset neurodegenerative disorders and reproductive choices. Diagnostic molecular neurogenetics laboratories have been faced with an ever-increasing range of disease genes that could be tested for and usually a finite budget with which to perform the possible testing. Neurogenetics has moved from one known disease gene, the Duchenne muscular dystrophy gene in July 1987, to hundreds of disease genes in 2011. It can be anticipated that with the advent of next generation sequencing (NGS), most, if not all, causative genes will be identified in the next few years. Any type of mutation possible in human DNA has been shown to cause genetic neuromuscular disorders, including point mutations, small insertions and deletions, large deletions and duplications, repeat expansions or contraction and somatic mosaicism. The diagnostic laboratory therefore has to be capable of a large number of techniques in order to identify the different mutation types and requires highly skilled staff. Mutations causing neuromuscular disorders affect the largest human proteins for example titin and nebulin. Successful molecular diagnosis can make invasive and expensive diagnostic procedures such as muscle biopsy unnecessary. Molecular diagnosis is currently largely based on Sanger sequencing, which at most can sequence a small number of exons in one gene at a time. NGS techniques will facilitate molecular diagnostics, but not for all types of mutations. For example, NGS is not good at identifying repeat expansions or copy number variations. Currently, diagnostic molecular neurogenetics is focused on identifying the causative mutation(s) in a patient. In the future, the focus might move to prevention, by identifying carriers of recessive diseases before they have affected children. The pathobiology of many of the diseases remains obscure, as do factors affecting disease severity. The aim of this review is to describe molecular diagnosis of genetic neuromuscular disorders in the past, the present and speculate on the future.
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Affiliation(s)
- Nigel G Laing
- Centre for Medical Research, University of Western Australia, Western Australian Institute for Medical Research, Nedlands, Western Australia, Australia.
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93
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Cullup T, Lamont PJ, Cirak S, Damian MS, Wallefeld W, Gooding R, Tan SV, Sheehan J, Muntoni F, Abbs S, Sewry CA, Dubowitz V, Laing NG, Jungbluth H. Mutations in MYH7 cause Multi-minicore Disease (MmD) with variable cardiac involvement. Neuromuscul Disord 2012; 22:1096-104. [PMID: 22784669 DOI: 10.1016/j.nmd.2012.06.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 05/28/2012] [Accepted: 06/12/2012] [Indexed: 10/28/2022]
Abstract
Central Core Disease (CCD) and Multi-minicore Disease (MmD) (the "core myopathies") have been mainly associated with mutations in the skeletal muscle ryanodine receptor (RYR1) and the selenoprotein N (SEPN1) gene. A proportion of cases remain unresolved. Mutations in MYH7 encoding the beta myosin heavy chain protein have been implicated in cardiac and, less frequently, skeletal muscle disorders. Here we report four patients from two families with a histopathological diagnosis of MmD, presenting in childhood with slowly progressive muscle weakness, more proximal in Family 1 and more distal in Family 2, and variable degrees of cardiorespiratory impairment evolving later in life. There was also a strong family history of sudden death in the first family. Muscle biopsies obtained in early childhood showed multiple minicores as the most prominent feature. Sequencing of the MYH7 gene revealed heterozygous missense mutations, c.4399C>G; p.Leu1467Val (exon 32) in Family 1 and c.4763G>C; p.Arg1588Pro (exon 34) in Family 2. These findings suggest MYH7 mutations as another cause of a myopathy with multiple cores, in particular if associated with dominant inheritance and cardiac involvement. However, clinical features previously associated with this genetic background, namely a more distal distribution of weakness and an associated cardiomyopathy, may only evolve over time.
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Affiliation(s)
- T Cullup
- DNA Laboratory, GSTS Pathology, Guy's Hospital, London, UK
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94
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New phenotype and pathology features in MYH7-related distal myopathy. Neuromuscul Disord 2012; 22:640-7. [PMID: 22521714 DOI: 10.1016/j.nmd.2012.03.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Revised: 02/06/2012] [Accepted: 03/02/2012] [Indexed: 11/22/2022]
Abstract
Laing distal myopathy is an autosomal dominant disease due to mutations in the gene encoding for the human slow-β myosin heavy chain, MYH7. Most reports describe it as a mild, early onset myopathy with involvement usually restricted to foot extensors, hand finger extensors and neck flexors, and unspecific findings on muscle biopsy. We identified the first two Italian families with Laing distal myopathy, harboring two novel mutations in the MYH7 gene and performed clinical, neurophysiological, pathological, muscle MRI and cardiological investigations on affected members from the two families. Subjects from one family presented a moderate-severe phenotype, with proximal together with distal involvement and even loss of ambulation at advanced age. One patient displayed atypical muscle biopsy findings including cytoplasmic bodies and myofibrillar myopathy-like features. Affected members from the second family shared a very mild phenotype, with weakness largely limited to long toe and foot extensors and/or late onset. No patient showed any sign of heart involvement. Our study significantly broadens the clinical and pathological spectrum of Laing distal myopathy. We suggest that MYH7 screening should be considered in undiagnosed late-onset distal myopathy or cytoplasmic body myopathy patients.
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95
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Salvi SS, Kumar RP, Ramachandra NB, Sparrow JC, Nongthomba U. Mutations in Drosophila myosin rod cause defects in myofibril assembly. J Mol Biol 2012; 419:22-40. [PMID: 22370558 DOI: 10.1016/j.jmb.2012.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 01/17/2012] [Accepted: 02/17/2012] [Indexed: 11/15/2022]
Abstract
The roles of myosin during muscle contraction are well studied, but how different domains of this protein are involved in myofibril assembly in vivo is far less understood. The indirect flight muscles (IFMs) of Drosophila melanogaster provide a good model for understanding muscle development and function in vivo. We show that two missense mutations in the rod region of the myosin heavy-chain gene, Mhc, give rise to IFM defects and abnormal myofibrils. These defects likely result from thick filament abnormalities that manifest during early sarcomere development or later by hypercontraction. The thick filament defects are accompanied by marked reduction in accumulation of flightin, a myosin binding protein, and its phosphorylated forms, which are required to stabilise thick filaments. We investigated with purified rod fragments whether the mutations affect the coiled-coil structure, rod aggregate size or rod stability. No significant changes in these parameters were detected, except for rod thermodynamic stability in one mutation. Molecular dynamics simulations suggest that these mutations may produce localised rod instabilities. We conclude that the aberrant myofibrils are a result of thick filament defects, but that these in vivo effects cannot be detected in vitro using the biophysical techniques employed. The in vivo investigation of these mutant phenotypes in IFM development and function provides a useful platform for studying myosin rod and thick filament formation generically, with application to the aetiology of human myosin rod myopathies.
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Affiliation(s)
- Sheetal S Salvi
- Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560 012, India
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96
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Ackerman MJ, Priori SG, Willems S, Berul C, Brugada R, Calkins H, Camm AJ, Ellinor PT, Gollob M, Hamilton R, Hershberger RE, Judge DP, Le Marec H, McKenna WJ, Schulze-Bahr E, Semsarian C, Towbin JA, Watkins H, Wilde A, Wolpert C, Zipes DP. HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies this document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA). Heart Rhythm 2012; 8:1308-39. [PMID: 21787999 DOI: 10.1016/j.hrthm.2011.05.020] [Citation(s) in RCA: 729] [Impact Index Per Article: 60.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Indexed: 10/18/2022]
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97
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Tasca G, Ricci E, Monforte M, Laschena F, Ottaviani P, Rodolico C, Barca E, Silvestri G, Iannaccone E, Mirabella M, Broccolini A. Muscle imaging findings in GNE myopathy. J Neurol 2012; 259:1358-65. [PMID: 22231866 DOI: 10.1007/s00415-011-6357-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/22/2011] [Accepted: 12/05/2011] [Indexed: 11/25/2022]
Abstract
GNE myopathy (MIM 600737) is an autosomal recessive muscle disease caused by mutations in the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene. Besides the typical phenotype, characterized by the initial involvement of the distal leg muscles that eventually spreads proximally with sparing of the quadriceps, uncommon presentations with a non-canonical clinical phenotype, unusual muscle biopsy findings or both are increasingly recognized. The aim of our study was to characterize the imaging pattern of pelvic and lower limb muscles in GNE myopathy, thus providing additional diagnostic clues useful in the identification of patients with atypical features. We retrospectively evaluated muscle MRI and CT scans of a cohort of 13 patients heterogeneous for GNE mutations and degree of clinical severity. We found that severe involvement of the biceps femoris short head and, to a lesser extent, of the gluteus minimus, tibialis anterior, extensor hallucis and digitorum longus, soleus and gastrocnemius medialis was consistently present even in patients with early or atypical disease. The vastus lateralis, not the entire quadriceps, was the only muscle spared in advanced stages, while the rectus femoris, vastus intermedius and medialis showed variable signs of fatty replacement. Younger patients showed hyperintensities on T2-weighted sequences in muscles with a normal or, more often, abnormal T1-weighted signal. Our results define a pattern of muscle involvement that appears peculiar to GNE myopathy. Although these findings need to be further validated in a larger cohort, we believe that the recognition of this pattern may be instrumental in the initial clinical assessment of patients with possible GNE myopathy.
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98
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Udd B. Distal myopathies – New genetic entities expand diagnostic challenge. Neuromuscul Disord 2012; 22:5-12. [DOI: 10.1016/j.nmd.2011.10.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 10/02/2011] [Accepted: 10/04/2011] [Indexed: 10/14/2022]
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99
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Solmaz SR, Chauhan R, Blobel G, Melčák I. Molecular architecture of the transport channel of the nuclear pore complex. Cell 2011; 147:590-602. [PMID: 22036567 PMCID: PMC3431207 DOI: 10.1016/j.cell.2011.09.034] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Revised: 06/28/2011] [Accepted: 09/12/2011] [Indexed: 01/02/2023]
Abstract
The nuclear pore complex encloses a central channel for nucleocytoplasmic transport, which is thought to consist of three nucleoporins, Nup54, Nup58, and Nup62. However, the structure and composition of the channel are elusive. We determined the crystal structures of the interacting domains between these nucleoporins and pieced together the molecular architecture of the mammalian transport channel. Located in the channel midplane is a flexible Nup54⋅Nup58 ring that can undergo large rearrangements yielding diameter changes from ∼20 to ∼40 nm. Nup62⋅Nup54 triple helices project alternately up and down from either side of the midplane ring and form nucleoplasmic and cytoplasmic entries. The channel consists of as many as 224 copies of the three nucleoporins, amounting to a molar mass of 12.3 MDa and contributing 256 phenylalanine-glycine repeat regions. We propose that the occupancy of these repeat regions with transport receptors modulates ring diameter and transport activity.
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Affiliation(s)
- Sozanne R Solmaz
- Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
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100
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Ackerman MJ, Priori SG, Willems S, Berul C, Brugada R, Calkins H, Camm AJ, Ellinor PT, Gollob M, Hamilton R, Hershberger RE, Judge DP, Le Marec H, McKenna WJ, Schulze-Bahr E, Semsarian C, Towbin JA, Watkins H, Wilde A, Wolpert C, Zipes DP. HRS/EHRA expert consensus statement on the state of genetic testing for the channelopathies and cardiomyopathies: this document was developed as a partnership between the Heart Rhythm Society (HRS) and the European Heart Rhythm Association (EHRA). Europace 2011; 13:1077-109. [PMID: 21810866 DOI: 10.1093/europace/eur245] [Citation(s) in RCA: 569] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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