@article {737, title = {ASC-1 Is a Cell Cycle Regulator Associated with Severe and Mild Forms of Myopathy.}, journal = {Ann Neurol}, volume = {87}, year = {2020}, month = {2020 02}, pages = {217-232}, abstract = {

OBJECTIVE: Recently, the ASC-1 complex has been identified as a mechanistic link between amyotrophic lateral sclerosis and spinal muscular atrophy (SMA), and 3 mutations of the ASC-1 gene TRIP4 have been associated with SMA or congenital myopathy. Our goal was to define ASC-1 neuromuscular function and the phenotypical spectrum associated with TRIP4 mutations.

METHODS: Clinical, molecular, histological, and magnetic resonance imaging studies were made in 5 families with 7 novel TRIP4 mutations. Fluorescence activated cell sorting and Western blot were performed in patient-derived fibroblasts and muscles and in Trip4 knocked-down C2C12 cells.

RESULTS: All mutations caused ASC-1 protein depletion. The clinical phenotype was purely myopathic, ranging from lethal neonatal to mild ambulatory adult patients. It included early onset axial and proximal weakness, scoliosis, rigid spine, dysmorphic facies, cutaneous involvement, respiratory failure, and in the older cases, dilated cardiomyopathy. Muscle biopsies showed multiminicores, nemaline rods, cytoplasmic bodies, caps, central nuclei, rimmed fibers, and/or mild endomysial fibrosis. ASC-1 depletion in C2C12 and in patient-derived fibroblasts and muscles caused accelerated proliferation, altered expression of cell cycle proteins, and/or shortening of the G0/G1 cell cycle phase leading to cell size reduction.

INTERPRETATION: Our results expand the phenotypical and molecular spectrum of TRIP4-associated disease to include mild adult forms with or without cardiomyopathy, associate ASC-1 depletion with isolated primary muscle involvement, and establish TRIP4 as a causative gene for several congenital muscle diseases, including nemaline, core, centronuclear, and cytoplasmic-body myopathies. They also identify ASC-1 as a novel cell cycle regulator with a key role in cell proliferation, and underline transcriptional coregulation defects as a novel pathophysiological mechanism. ANN NEUROL 2020;87:217-232.

}, keywords = {Adult, Amino Acid Transport System y+, Cell Cycle, Cells, Cultured, Child, Child, Preschool, Female, Fibroblasts, Humans, Infant, Male, Middle Aged, Muscle Proteins, Muscle, Skeletal, Muscular Diseases, Mutation, Pedigree, Phenotype, Transcription Factors}, issn = {1531-8249}, doi = {10.1002/ana.25660}, author = {Villar-Quiles, Roc{\'\i}o N and Catervi, Fabio and Cabet, Eva and Juntas-Morales, Raul and Genetti, Casie A and Gidaro, Teresa and Koparir, Asuman and Yuksel, Adnan and Coppens, Sandra and Deconinck, Nicolas and Pierce-Hoffman, Emma and Lornage, Xavi{\`e}re and Durigneux, Julien and Laporte, Jocelyn and Rendu, John and Romero, Norma B and Beggs, Alan H and Servais, Laurent and Coss{\'e}e, Mireille and Oliv{\'e}, Montse and B{\"o}hm, Johann and Duband-Goulet, Isabelle and Ferreiro, Ana} } @article {756, title = {Congenital myasthenic syndrome with mild intellectual disability caused by a recurrent SLC25A1 variant.}, journal = {Eur J Hum Genet}, volume = {28}, year = {2020}, month = {2020 03}, pages = {373-377}, abstract = {

Congenital myasthenic syndromes (CMS) are a clinically and genetically heterogeneous group of disorders caused by mutations which lead to impaired neuromuscular transmission. SLC25A1 encodes a mitochondrial citrate carrier, associated mainly with the severe neurometabolic disease combined D-2- and L-2-hydroxyglutaric aciduria (D/L-2-HGA). We previously reported a single family with a homozygous missense variant in SLC25A1 with a phenotype restricted to relatively mild CMS with intellectual disability, but to date no additional cases of this CMS subtype had been reported. Here, we performed whole exome sequencing (WES) in three additional and unrelated families presenting with CMS and mild intellectual disability to identify the underlying causative gene. The WES analysis revealed the presence of a homozygous c.740G>A; p.(Arg247Gln) missense SLC25A1 variant, the same SLC25A1 variant as identified in the original family with this phenotype. Electron microscopy of muscle from two cases revealed enlarged and accumulated mitochondria. Haplotype analysis performed in two unrelated families suggested that this variant is a result of recurrent mutation and not a founder effect. This suggests that p.(Arg247Gln) is associated with a relatively mild CMS phenotype with subtle mitochondrial abnormalities, while other variants in this gene cause more severe neurometabolic disease. In conclusion, the p.(Arg247Gln) SLC25A1 variant should be considered in patients presenting with a presynaptic CMS phenotype, particularly with accompanying intellectual disability.

}, keywords = {Adult, Female, Haplotypes, Homozygote, Humans, Intellectual Disability, Male, Mitochondrial Proteins, Muscle, Skeletal, Mutation, Missense, Myasthenic Syndromes, Congenital, Organic Anion Transporters}, issn = {1476-5438}, doi = {10.1038/s41431-019-0506-2}, author = {Balaraju, Sunitha and Topf, Ana and McMacken, Grace and Kumar, Veeramani Preethish and Pechmann, Astrid and Roper, Helen and Vengalil, Seena and Polavarapu, Kiran and Nashi, Saraswati and MAHjan, Niranjan Prakash and Barbosa, Ines A and Deshpande, Charu and Taylor, Robert W and Cossins, Judith and Beeson, David and Laurie, Steven and Kirschner, Janbernd and Horvath, Rita and McFarland, Robert and Nalini, Atchayaram and Lochm{\"u}ller, Hanns} } @article {814, title = {Mutations in MYLPF Cause a Novel Segmental Amyoplasia that Manifests as Distal Arthrogryposis.}, journal = {Am J Hum Genet}, volume = {107}, year = {2020}, month = {2020 08 06}, pages = {293-310}, abstract = {

We identified ten persons in six consanguineous families with distal arthrogryposis (DA) who had congenital contractures, scoliosis, and short stature. Exome sequencing revealed that each affected person was homozygous for one of two different rare variants (c.470G>T [p.Cys157Phe] or c.469T>C [p.Cys157Arg]) affecting the same residue of myosin light chain, phosphorylatable, fast skeletal muscle (MYLPF). In a seventh family, a c.487G>A (p.Gly163Ser) variant in MYLPF arose de novo in a father, who transmitted it to his son. In an eighth family comprised of seven individuals with dominantly inherited DA, a c.98C>T (p.Ala33Val) variant segregated in all four persons tested. Variants in MYLPF underlie both dominant and recessively inherited DA. Mylpf protein models suggest that the residues associated with dominant DA interact with myosin whereas the residues altered in families with recessive DA only indirectly impair this interaction. Pathological and histological exam of a foot amputated from an affected child revealed complete absence of skeletal muscle (i.e., segmental amyoplasia). To investigate the mechanism for this finding, we generated an animal model for partial MYLPF impairment by knocking out zebrafish mylpfa. The mylpfa mutant had reduced trunk contractile force and complete pectoral fin paralysis, demonstrating that mylpf impairment most severely affects limb movement. mylpfa mutant muscle weakness was most pronounced in an appendicular muscle and was explained by reduced myosin activity and fiber degeneration. Collectively, our findings demonstrate that partial loss of MYLPF function can lead to congenital contractures, likely as a result of degeneration of skeletal muscle in the distal limb.

}, keywords = {Adolescent, Amino Acid Sequence, Animals, Arthrogryposis, Child, Contracture, Extremities, Female, Humans, Male, Muscle, Skeletal, Musculoskeletal Abnormalities, Mutation, Myosin Light Chains, Myosins, Pedigree, Young Adult, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2020.06.014}, author = {Chong, Jessica X and Talbot, Jared C and Teets, Emily M and Previs, Samantha and Martin, Brit L and Shively, Kathryn M and Marvin, Colby T and Aylsworth, Arthur S and Saadeh-Haddad, Reem and Schatz, Ulrich A and Inzana, Francesca and Ben-Omran, Tawfeg and Almusafri, Fatima and Al-Mulla, Mariam and Buckingham, Kati J and Harel, Tamar and Mor-Shaked, Hagar and Radhakrishnan, Periyasamy and Girisha, Katta M and Nayak, Shalini S and Shukla, Anju and Dieterich, Klaus and Faure, Julien and Rendu, John and Capri, Yline and Latypova, X{\'e}nia and Nickerson, Deborah A and Warshaw, David M and Janssen, Paul M L and Amacher, Sharon L and Bamshad, Michael J} } @article {978, title = {POGLUT1 biallelic mutations cause myopathy with reduced satellite cells, α-dystroglycan hypoglycosylation and a distinctive radiological pattern.}, journal = {Acta Neuropathol}, volume = {139}, year = {2020}, month = {2020 03}, pages = {565-582}, abstract = {

Protein O-glucosyltransferase 1 (POGLUT1) activity is critical for the Notch signaling pathway, being one of the main enzymes responsible for the glycosylation of the extracellular domain of Notch receptors. A biallelic mutation in the POGLUT1 gene has been reported in one family as the cause of an adult-onset limb-girdle muscular dystrophy (LGMD R21; OMIM$\#$ 617232). As the result of a collaborative international effort, we have identified the first cohort of 15 patients with LGMD R21, from nine unrelated families coming from different countries, providing a reliable phenotype-genotype and mechanistic insight. Patients carrying novel mutations in POGLUT1 all displayed a clinical picture of limb-girdle muscle weakness. However, the age at onset was broadened from adult to congenital and infantile onset. Moreover, we now report that the unique muscle imaging pattern of "inside-to-outside" fatty degeneration observed in the original cases is indeed a defining feature of POGLUT1 muscular dystrophy. Experiments on muscle biopsies from patients revealed a remarkable and consistent decrease in the level of the NOTCH1 intracellular domain, reduction of the pool of satellite cells (SC), and evidence of α-dystroglycan hypoglycosylation. In vitro biochemical and cell-based assays suggested a pathogenic role of the novel POGLUT1 mutations, leading to reduced enzymatic activity and/or protein stability. The association between the POGLUT1 variants and the muscular phenotype was established by in vivo experiments analyzing the indirect flight muscle development in transgenic Drosophila, showing that the human POGLUT1 mutations reduced its myogenic activity. In line with the well-known role of the Notch pathway in the homeostasis of SC and muscle regeneration, SC-derived myoblasts from patients{\textquoteright} muscle samples showed decreased proliferation and facilitated differentiation. Together, these observations suggest that alterations in SC biology caused by reduced Notch1 signaling result in muscular dystrophy in LGMD R21 patients, likely with additional contribution from α-dystroglycan hypoglycosylation. This study settles the muscular clinical phenotype linked to POGLUT1 mutations and establishes the pathogenic mechanism underlying this muscle disorder. The description of a specific imaging pattern of fatty degeneration and muscle pathology with a decrease of α-dystroglycan glycosylation provides excellent tools which will help diagnose and follow up LGMD R21 patients.

}, keywords = {Animals, Animals, Genetically Modified, Drosophila melanogaster, Dystroglycans, Female, Genetic Association Studies, Glucosyltransferases, Glycosylation, Humans, Male, Muscle, Skeletal, Muscular Dystrophies, Limb-Girdle, Mutation, Pedigree, Satellite Cells, Skeletal Muscle}, issn = {1432-0533}, doi = {10.1007/s00401-019-02117-6}, author = {Servi{\'a}n-Morilla, E and Cabrera-Serrano, M and Johnson, K and Pandey, A and Ito, A and Rivas, E and Chamova, T and Muelas, N and Mongini, T and Nafissi, S and Claeys, K G and Grewal, R P and Takeuchi, M and Hao, H and B{\"o}nnemann, C and Lopes Abath Neto, O and Medne, L and Brandsema, J and T{\"o}pf, A and Taneva, A and Vilchez, J J and Tournev, I and Haltiwanger, R S and Takeuchi, H and Jafar-Nejad, H and Straub, V and Paradas, Carmen} } @article {561, title = {Novel SPEG mutations in congenital myopathies: Genotype-phenotype correlations.}, journal = {Muscle Nerve}, volume = {59}, year = {2019}, month = {2019 03}, pages = {357-362}, abstract = {

INTRODUCTION: Centronuclear myopathies (CNMs) are a subtype of congenital myopathies (CMs) characterized by muscle weakness, predominant type 1 fibers, and increased central nuclei. SPEG (striated preferentially expressed protein kinase) mutations have recently been identified in 7 CM patients (6 with CNMs). We report 2 additional patients with SPEG mutations expanding the phenotype and evaluate genotype-phenotype correlations associated with SPEG mutations.

METHODS: Using whole exome/genome sequencing in CM families, we identified novel recessive SPEG mutations in 2 patients.

RESULTS: Patient 1, with severe muscle weakness requiring respiratory support, dilated cardiomyopathy, ophthalmoplegia, and findings of nonspecific CM on muscle biopsy carried a homozygous SPEG mutation (p.Val3062del). Patient 2, with milder muscle weakness, ophthalmoplegia, and CNM carried compound heterozygous mutations (p.Leu728Argfs*82) and (p.Val2997Glyfs*52).

CONCLUSIONS: The 2 patients add insight into genotype-phenotype correlations of SPEG-associated CMs. Clinicians should consider evaluating a CM patient for SPEG mutations even in the absence of CNM features. Muscle Nerve 59:357-362, 2019.

}, keywords = {Biopsy, Child, Child, Preschool, Consanguinity, Exome, Female, Genetic Association Studies, Humans, Infant, Male, Muscle Proteins, Muscle Weakness, Muscle, Skeletal, Mutation, Myopathies, Structural, Congenital, Protein-Serine-Threonine Kinases, Sequence Analysis}, issn = {1097-4598}, doi = {10.1002/mus.26378}, author = {Qualls, Anita E and Donkervoort, Sandra and Herkert, Johanna C and D{\textquoteright}Gama, Alissa M and Bharucha-Goebel, Diana and Collins, James and Chao, Katherine R and Foley, A Reghan and Schoots, Mirthe H and Jongbloed, Jan D H and B{\"o}nnemann, Carsten G and Agrawal, Pankaj B} } @article {571, title = {Recessive mutations in muscle-specific isoforms of FXR1 cause congenital multi-minicore myopathy.}, journal = {Nat Commun}, volume = {10}, year = {2019}, month = {2019 02 15}, pages = {797}, abstract = {

FXR1 is an alternatively spliced gene that encodes RNA binding proteins (FXR1P) involved in muscle development. In contrast to other tissues, cardiac and skeletal muscle express two FXR1P isoforms that incorporate an additional exon-15. We report that recessive mutations in this particular exon of FXR1 cause congenital multi-minicore myopathy in humans and mice. Additionally, we show that while Myf5-dependent depletion of all FXR1P isoforms is neonatal lethal, mice carrying mutations in exon-15 display non-lethal myopathies which vary in severity depending on the specific effect of each mutation on the protein.

}, keywords = {Animals, Cells, Cultured, Exons, Gene Expression, Genes, Recessive, Genetic Predisposition to Disease, HEK293 Cells, HeLa Cells, Humans, Mice, Transgenic, Muscle, Skeletal, Mutation, Myopathies, Structural, Congenital, Ophthalmoplegia, RNA-Binding Proteins, Ryanodine Receptor Calcium Release Channel}, issn = {2041-1723}, doi = {10.1038/s41467-019-08548-9}, author = {Esta{\~n}, Mar{\'\i}a Cristina and Fern{\'a}ndez-N{\'u}{\~n}ez, Elisa and Zaki, Maha S and Esteban, Mar{\'\i}a Isabel and Donkervoort, Sandra and Hawkins, Cynthia and Caparros-Martin, Jos{\'e} A and Saade, Dimah and Hu, Ying and Bolduc, Veronique and Chao, Katherine Ru-Yui and Nevado, Juli{\'a}n and Lamuedra, Ana and Largo, Raquel and Herrero-Beaumont, Gabriel and Regadera, Javier and Hernandez-Chico, Concepci{\'o}n and Tizzano, Eduardo F and Martinez-Glez, Victor and Carvajal, Jaime J and Zong, Ruiting and Nelson, David L and Otaify, Ghada A and Temtamy, Samia and Aglan, Mona and Issa, Mahmoud and B{\"o}nnemann, Carsten G and Lapunzina, Pablo and Yoon, Grace and Ruiz-Perez, Victor L} } @article {490, title = {Variants in EXOSC9 Disrupt the RNA Exosome and Result in Cerebellar Atrophy with Spinal Motor Neuronopathy.}, journal = {Am J Hum Genet}, volume = {102}, year = {2018}, month = {2018 05 03}, pages = {858-873}, abstract = {

The exosome is a conserved multi-protein complex that is essential for correct RNA processing. Recessive variants in exosome components EXOSC3, EXOSC8, and RBM7 cause various constellations of pontocerebellar hypoplasia (PCH), spinal muscular atrophy (SMA), and central nervous system demyelination. Here, we report on four unrelated affected individuals with recessive variants in EXOSC9 and the effect of the variants on the function of the RNA exosome in~vitro in affected individuals{\textquoteright} fibroblasts and skeletal muscle and in~vivo in zebrafish. The clinical presentation was severe, early-onset, progressive SMA-like motor neuronopathy, cerebellar atrophy, and in one affected individual, congenital fractures of the long bones. Three affected individuals of different ethnicity carried the homozygous c.41T>C (p.Leu14Pro) variant, whereas one affected individual was compound heterozygous for c.41T>C (p.Leu14Pro) and c.481C>T (p.Arg161). We detected reduced EXOSC9 in fibroblasts and skeletal muscle and observed a reduction of the whole multi-subunit exosome complex on blue-native polyacrylamide gel electrophoresis. RNA sequencing of fibroblasts and skeletal muscle detected significant >2-fold changes in genes involved in neuronal development and cerebellar and motor neuron degeneration, demonstrating the widespread effect of the variants. Morpholino oligonucleotide knockdown and CRISPR/Cas9-mediated mutagenesis of exosc9 in zebrafish recapitulated aspects of the human phenotype, as they have in other zebrafish models of exosomal disease. Specifically, portions of the cerebellum and hindbrain were absent, and motor neurons failed to develop and migrate properly. In summary, we show that variants in EXOSC9 result in a neurological syndrome combining cerebellar atrophy and spinal motoneuronopathy, thus expanding the list of human exosomopathies.

}, keywords = {Amino Acid Sequence, Animals, Atrophy, Base Sequence, Cerebellum, Child, Preschool, Exosome Multienzyme Ribonuclease Complex, Exosomes, Female, Fibroblasts, Gene Knockdown Techniques, Genetic Variation, Haplotypes, Humans, Infant, Male, Motor Neurons, Muscle, Skeletal, Pedigree, RNA-Binding Proteins, Spinal Cord, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2018.03.011}, author = {Burns, David T and Donkervoort, Sandra and M{\"u}ller, Juliane S and Knierim, Ellen and Bharucha-Goebel, Diana and Faqeih, Eissa Ali and Bell, Stephanie K and AlFaifi, Abdullah Y and Monies, Dorota and Millan, Francisca and Retterer, Kyle and Dyack, Sarah and MacKay, Sara and Morales-Gonzalez, Susanne and Giunta, Michele and Munro, Benjamin and Hudson, Gavin and Scavina, Mena and Baker, Laura and Massini, Tara C and Lek, Monkol and Hu, Ying and Ezzo, Daniel and Alkuraya, Fowzan S and Kang, Peter B and Griffin, Helen and Foley, A Reghan and Schuelke, Markus and Horvath, Rita and B{\"o}nnemann, Carsten G} } @article {443, title = {Complex phenotypes associated with STIM1 mutations in both coiled coil and EF-hand domains.}, journal = {Neuromuscul Disord}, volume = {27}, year = {2017}, month = {2017 Sep}, pages = {861-872}, abstract = {

Dominant mutations in STIM1 are a cause of three allelic conditions: tubular aggregate myopathy, Stormorken syndrome (a complex phenotype including myopathy, hyposplenism, hypocalcaemia and bleeding diathesis), and a platelet dysfunction disorder, York platelet syndrome. Previous reports have suggested a genotype-phenotype correlation with mutations in the N-terminal EF-hand domain associated with tubular aggregate myopathy, and a common mutation at p.R304W in a coiled coil domain associated with Stormorken syndrome. In this study individuals with STIM1 variants were identified by exome sequencing or STIM1 direct sequencing, and assessed for neuromuscular, haematological and biochemical evidence of the allelic disorders of STIM1. STIM1 mutations were investigated by fibroblast calcium imaging and 3D modelling. Six individuals with STIM1 mutations, including two novel mutations (c.262A>G (p.S88G) and c.911G>A (p.R304Q)), were identified. Extra-neuromuscular symptoms including thrombocytopenia, platelet dysfunction, hypocalcaemia or hyposplenism were present in 5/6 patients with mutations in both the EF-hand and CC domains. 3/6 patients had psychiatric disorders, not previously reported in STIM1 disease. Review of published STIM1 patients (n = 49) confirmed that neuromuscular symptoms are present in most patients. We conclude that the phenotype associated with activating STIM1 mutations frequently includes extra-neuromuscular features such as hypocalcaemia, hypo-/asplenia and platelet dysfunction regardless of mutation domain.

}, keywords = {Adult, Blood Platelet Disorders, Calcium, Cell Culture Techniques, DNA Mutational Analysis, Dyslexia, Erythrocytes, Abnormal, Family Health, Female, Fibroblasts, Genetic Association Studies, Humans, Ichthyosis, Magnetic Resonance Imaging, Male, Microscopy, Electron, Middle Aged, Migraine Disorders, Miosis, Models, Molecular, Muscle Fatigue, Muscle, Skeletal, Mutation, Myopathies, Structural, Congenital, NAD, Neoplasm Proteins, Spleen, Stromal Interaction Molecule 1}, issn = {1873-2364}, doi = {10.1016/j.nmd.2017.05.002}, author = {Harris, Elizabeth and Burki, Umar and Marini-Bettolo, Chiara and Neri, Marcella and Scotton, Chiara and Hudson, Judith and Bertoli, Marta and Evangelista, Teresinha and Vroling, Bas and Polvikoski, Tuomo and Roberts, Mark and Topf, Ana and Bushby, Kate and McArthur, Daniel and Lochm{\"u}ller, Hanns and Ferlini, Alessandra and Straub, Volker and Barresi, Rita} } @article {638, title = {A defect in myoblast fusion underlies Carey-Fineman-Ziter syndrome.}, journal = {Nat Commun}, volume = {8}, year = {2017}, month = {2017 07 06}, pages = {16077}, abstract = {

Multinucleate cellular syncytial formation is a hallmark of skeletal muscle differentiation. Myomaker, encoded by Mymk (Tmem8c), is a well-conserved plasma membrane protein required for myoblast fusion to form multinucleated myotubes in mouse, chick, and zebrafish. Here, we report that autosomal recessive mutations in MYMK (OMIM 615345) cause Carey-Fineman-Ziter syndrome in humans (CFZS; OMIM 254940) by reducing but not eliminating MYMK function. We characterize MYMK-CFZS as a congenital myopathy with marked facial weakness and additional clinical and pathologic features that distinguish it from other congenital neuromuscular syndromes. We show that a heterologous cell fusion assay in vitro and allelic complementation experiments in mymk knockdown and mymk zebrafish in vivo can differentiate between MYMK wild type, hypomorphic and null alleles. Collectively, these data establish that MYMK activity is necessary for normal muscle development and maintenance in humans, and expand the spectrum of congenital myopathies to include cell-cell fusion deficits.

}, keywords = {Adult, Amino Acid Sequence, Animals, Cell Fusion, Child, Disease Models, Animal, Embryo, Nonmammalian, Female, Gene Expression, Genes, Recessive, Genetic Complementation Test, Humans, Infant, Male, Membrane Proteins, Mobius Syndrome, Morphogenesis, Muscle Proteins, Muscle, Skeletal, Muscular Diseases, Mutation, Myoblasts, Pedigree, Pierre Robin Syndrome, Sequence Alignment, Sequence Homology, Amino Acid, Zebrafish, Zebrafish Proteins}, issn = {2041-1723}, doi = {10.1038/ncomms16077}, author = {Di Gioia, Silvio Alessandro and Connors, Samantha and Matsunami, Norisada and Cannavino, Jessica and Rose, Matthew F and Gilette, Nicole M and Artoni, Pietro and de Macena Sobreira, Nara Lygia and Chan, Wai-Man and Webb, Bryn D and Robson, Caroline D and Cheng, Long and Van Ryzin, Carol and Ramirez-Martinez, Andres and Mohassel, Payam and Leppert, Mark and Scholand, Mary Beth and Grunseich, Christopher and Ferreira, Carlos R and Hartman, Tyler and Hayes, Ian M and Morgan, Tim and Markie, David M and Fagiolini, Michela and Swift, Amy and Chines, Peter S and Speck-Martins, Carlos E and Collins, Francis S and Jabs, Ethylin Wang and B{\"o}nnemann, Carsten G and Olson, Eric N and Carey, John C and Robertson, Stephen P and Manoli, Irini and Engle, Elizabeth C} } @article {455, title = {Variants in the Oxidoreductase PYROXD1 Cause Early-Onset Myopathy with Internalized Nuclei and Myofibrillar Disorganization.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Nov 03}, pages = {1086-1105}, abstract = {

This study establishes PYROXD1 variants as a cause of early-onset myopathy and uses biospecimens and cell lines, yeast, and zebrafish models to elucidate the fundamental role of PYROXD1 in skeletal muscle. Exome sequencing identified recessive variants in PYROXD1 in nine probands from five families. Affected individuals presented in infancy or childhood with slowly progressive proximal and distal weakness, facial weakness, nasal speech, swallowing difficulties, and normal to moderately elevated creatine kinase. Distinctive histopathology showed abundant internalized nuclei, myofibrillar disorganization, desmin-positive inclusions, and thickened Z-bands. PYROXD1 is a nuclear-cytoplasmic pyridine nucleotide-disulphide reductase (PNDR). PNDRs are flavoproteins (FAD-binding) and catalyze pyridine-nucleotide-dependent (NAD/NADH) reduction of thiol residues in other proteins. Complementation experiments in yeast lacking glutathione reductase glr1 show that human PYROXD1 has reductase activity that is strongly impaired by the disease-associated missense mutations. Immunolocalization studies in human muscle and zebrafish myofibers demonstrate that PYROXD1 localizes to the nucleus and to striated sarcomeric compartments. Zebrafish with ryroxD1 knock-down recapitulate features of PYROXD1 myopathy with sarcomeric disorganization, myofibrillar aggregates, and marked swimming defect. We characterize variants in the oxidoreductase PYROXD1 as a cause of early-onset myopathy with distinctive histopathology and introduce altered redox regulation as a primary cause of congenital muscle disease.

}, keywords = {Amino Acid Sequence, Animals, Cell Nucleus, Cercopithecus aethiops, Cohort Studies, COS Cells, Creatine Kinase, Cytoplasm, Distal Myopathies, ELAV-Like Protein 4, Female, Flavoproteins, Gene Deletion, Genetic Variation, Genome-Wide Association Study, Glutathione Reductase, HEK293 Cells, Humans, Male, Muscle, Skeletal, Mutation, Missense, Myopathies, Structural, Congenital, Oxidoreductases, Pedigree, Protein Conformation, Saccharomyces cerevisiae Proteins, Zebrafish}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.09.005}, author = {O{\textquoteright}Grady, Gina L and Best, Heather A and Sztal, Tamar E and Schartner, Vanessa and Sanjuan-Vazquez, Myriam and Donkervoort, Sandra and Abath Neto, Osorio and Sutton, Roger Bryan and Ilkovski, Biljana and Romero, Norma Beatriz and Stojkovic, Tanya and Dastgir, Jahannaz and Waddell, Leigh B and Boland, Anne and Hu, Ying and Williams, Caitlin and Ruparelia, Avnika A and Maisonobe, Thierry and Peduto, Anthony J and Reddel, Stephen W and Lek, Monkol and Tukiainen, Taru and Cummings, Beryl B and Joshi, Himanshu and Nectoux, Juliette and Brammah, Susan and Deleuze, Jean-Fran{\c c}ois and Ing, Viola Oorschot and Ramm, Georg and Ardicli, Didem and Nowak, Kristen J and Talim, Beril and Topaloglu, Haluk and Laing, Nigel G and North, Kathryn N and MacArthur, Daniel G and Friant, Sylvie and Clarke, Nigel F and Bryson-Richardson, Robert J and B{\"o}nnemann, Carsten G and Laporte, Jocelyn and Cooper, Sandra T} } @article {322, title = {Facioscapulohumeral muscular dystrophy: consequences of chromatin relaxation.}, journal = {Curr Opin Neurol}, volume = {25}, year = {2012}, month = {2012 Oct}, pages = {614-20}, abstract = {

PURPOSE OF REVIEW: In recent years, we have seen remarkable progress in our understanding of the disease mechanism underlying facioscapulohumeral muscular dystrophy (FSHD). The purpose of this review is to provide a comprehensive overview of our current understanding of the disease mechanism and to discuss the observations supporting the possibility of a developmental defect in this disorder.

RECENT FINDINGS: In the majority of cases, FSHD is caused by contraction of the D4Z4 repeat array (FSHD1). This results in local chromatin relaxation and stable expression of the DUX4 retrogene in skeletal muscle, but only when a polymorphic DUX4 polyadenylation signal is present. In some cases (FSHD2), D4Z4 chromatin relaxation and stable DUX4 expression occur in the absence of D4Z4 array contraction. DUX4 is a germline transcription factor and its expression in skeletal muscle leads to activation of early stem cell and germline programs and transcriptional activation of retroelements.

SUMMARY: Recent studies have provided a plausible disease mechanism for FSHD in which FSHD results from inappropriate expression of the germline transcription factor DUX4. The genes regulated by DUX4 suggest several mechanisms of muscle damage, and provide potential biomarkers and therapeutic targets that should be investigated in future studies.

}, keywords = {Animals, Chromatin, Homeodomain Proteins, Humans, Muscle, Skeletal, Muscular Dystrophy, Facioscapulohumeral, Transcription, Genetic}, issn = {1473-6551}, doi = {10.1097/WCO.0b013e328357f22d}, author = {van der Maarel, Silv{\`e}re M and Miller, Daniel G and Tawil, Rabi and Filippova, Galina N and Tapscott, Stephen J} }