@article {824, title = {Collagen VI-related limb-girdle syndrome caused by frequent mutation in COL6A3 gene with conflicting reports of pathogenicity.}, journal = {Neuromuscul Disord}, volume = {30}, year = {2020}, month = {2020 06}, pages = {483-491}, abstract = {

Recently the scientific community has started to view Bethlem myopathy 1 and Ullrich congenital muscular dystrophy as two extremes of a collagen VI-related myopathy spectrum rather than two separate entities, as both are caused by mutations in one of the collagen VI genes. Here we report three individuals in two families who are homozygous for a COL6A3 mutation (c.7447A> G; p.Lys2483Glu), and compare their clinical features with seven previously published cases. Individuals carrying homozygous or compound heterozygous c.7447A> G, (p.Lys2483Glu) mutation exhibit mild phenotype without loss of ambulation, similar to the cases described previously as Collagen VI-related limb-girdle syndrome. The phenotype could arise due to an aberrant assembly of Von Willebrand factor A domains. Based on these data, we propose that c.7447A> G, (p.Lys2483Glu) is a common pathogenic mutation.

}, issn = {1873-2364}, doi = {10.1016/j.nmd.2020.03.010}, author = {Stavusis, Janis and Micule, Ieva and Wright, Nathan T and Straub, Volker and Topf, Ana and Panad{\'e}s-de Oliveira, Lu{\'\i}sa and Dom{\'\i}nguez-Gonz{\'a}lez, Cristina and Inashkina, Inna and Kidere, Dita and Chrestian, Nicolas and Lace, Baiba} } @article {943, title = {Expanding the disease phenotype of ADSSL1-associated myopathy in non-Korean patients.}, journal = {Neuromuscul Disord}, volume = {30}, year = {2020}, month = {2020 04}, pages = {310-314}, abstract = {

Adenylosuccinate synthase (ADSSL1) is a muscle specific enzyme involved in the purine nucleotide cycle and responsible for the conversion of inosine monophosphate to adenosine monophosphate. Since 2016, when mutations in the ADSSL1 gene were first described to be associated with an adult onset distal myopathy, nine patients with compound heterozygous variants in the ADSSL1 gene, all of Korean origin, have been identified. Here we report a novel ADSSL1 mutation and describe two sporadic cases of Turkish and Indian origin. Many of the clinical features of both patients and muscle histopathology and muscle MRI findings, were in accordance with previously reported findings in the adult onset distal myopathy individuals. However, one of our patients presented with progressive, proximally pronounced weakness, severe muscle atrophy and early contractures. Thus, mutations in ADSSL1 have to be considered in patients with both distal and proximal muscle weakness and across various ethnicities.

}, issn = {1873-2364}, doi = {10.1016/j.nmd.2020.02.006}, author = {Mroczek, Magdalena and Durmus, Hacer and Bijarnia-MAHy, Sunita and Topf, Ana and Ghaoui, Roula and Bryen, Samantha and Duff, Jennifer and England, Eleina and Cooper, Sandra T and MacArthur, Daniel G and Straub, Volker} } @article {973, title = {Four Individuals with a Homozygous Mutation in Exon 1f of the Gene and Associated Myasthenic Features.}, journal = {Genes (Basel)}, volume = {11}, year = {2020}, month = {2020 06 27}, abstract = {

We identified the known c.1_9del mutation in the gene in four unrelated females from consanguineous families of Turkish origin. All individuals presented with slowly progressive limb-girdle weakness without any dermatological findings, and dystrophic changes observed in their muscle biopsies. Additionally, the neurological examination revealed ptosis, facial weakness, fatigability, and muscle cramps in all four cases. In two patients, repetitive nerve stimulation showed a borderline decrement and a high jitter was detected in all patients by single-fiber electromyography. Clinical improvement was observed after treatment with pyridostigmine and salbutamol was started. We further characterize the phenotype of patients with limb-girdle muscular dystrophy R17 clinically, by muscle magnetic resonance imaging (MRI) features and by describing a common 3.8 Mb haplotype in three individuals from the same geographical region. In addition, we review the neuromuscular symptoms associated with mutations and the role of plectin in the neuromuscular junction.

}, keywords = {Adolescent, Adult, Child, Exons, Female, Homozygote, Humans, Muscular Dystrophies, Limb-Girdle, Mutation, Myasthenic Syndromes, Congenital, Phenotype, Plectin}, issn = {2073-4425}, doi = {10.3390/genes11070716}, author = {Mroczek, Magdalena and Durmus, Hacer and Topf, Ana and Parman, Yesim and Straub, Volker} } @article {713, title = {Recurrent TTN metatranscript-only c.39974-11T>G splice variant associated with autosomal recessive arthrogryposis multiplex congenita and myopathy.}, journal = {Hum Mutat}, volume = {41}, year = {2020}, month = {2020 02}, pages = {403-411}, abstract = {

We present eight families with arthrogryposis multiplex congenita and myopathy bearing a TTN intron 213 extended splice-site variant (NM_001267550.1:c.39974-11T>G), inherited in trans with a second pathogenic TTN variant. Muscle-derived RNA studies of three individuals confirmed mis-splicing induced by the c.39974-11T>G variant; in-frame exon 214 skipping or use of a cryptic 3{\textquoteright} splice-site effecting a frameshift. Confounding interpretation of pathogenicity is the absence of exons 213-217 within the described skeletal muscle TTN N2A isoform. However, RNA-sequencing from 365 adult human gastrocnemius samples revealed that 56\% specimens predominantly include exons 213-217 in TTN transcripts (inclusion rate >=66\%). Further, RNA-sequencing of five fetal muscle samples confirmed that 4/5 specimens predominantly include exons 213-217 (fifth sample inclusion rate 57\%). Contractures improved significantly with age for four individuals, which may be linked to decreased expression of pathogenic fetal transcripts. Our study extends emerging evidence supporting a vital developmental role for TTN isoforms containing metatranscript-only exons.

}, issn = {1098-1004}, doi = {10.1002/humu.23938}, author = {Bryen, Samantha J and Ewans, Lisa J and Pinner, Jason and MacLennan, Suzanna C and Donkervoort, Sandra and Castro, Diana and Topf, Ana and O{\textquoteright}Grady, Gina and Cummings, Beryl and Chao, Katherine R and Weisburd, Ben and Francioli, Laurent and Faiz, Fathimath and Bournazos, Adam M and Hu, Ying and Grosmann, Carla and Malicki, Denise M and Doyle, Helen and Witting, Nanna and Vissing, John and Claeys, Kristl G and Urankar, Kathryn and Beleza-Meireles, Ana and Baptista, Julia and Ellard, Sian and Savarese, Marco and Johari, Mridul and Vihola, Anna and Udd, Bjarne and Majumdar, Anirban and Straub, Volker and B{\"o}nnemann, Carsten G and MacArthur, Daniel G and Davis, Mark R and Cooper, Sandra T} } @article {911, title = {Sequential targeted exome sequencing of 1001 patients affected by unexplained limb-girdle weakness.}, journal = {Genet Med}, volume = {22}, year = {2020}, month = {2020 09}, pages = {1478-1488}, abstract = {

PURPOSE: Several hundred genetic muscle diseases have been described, all of which are rare. Their clinical and genetic heterogeneity means that a genetic diagnosis is challenging. We established an international consortium, MYO-SEQ, to aid the work-ups of muscle disease patients and to better understand disease etiology.

METHODS: Exome sequencing was applied to 1001 undiagnosed patients recruited from more than 40 neuromuscular disease referral centers; standardized phenotypic information was collected for each patient. Exomes were examined for variants in 429 genes associated with muscle conditions.

RESULTS: We identified suspected pathogenic variants in 52\% of patients across 87 genes. We detected 401 novel variants, 116 of which were recurrent. Variants in CAPN3, DYSF, ANO5, DMD, RYR1, TTN, COL6A2, and SGCA collectively accounted for over half of the solved cases; while variants in newer disease genes, such as BVES and POGLUT1, were also found. The remaining well-characterized unsolved patients (48\%) need further investigation.

CONCLUSION: Using our unique infrastructure, we developed a pathway to expedite muscle disease diagnoses. Our data suggest that exome sequencing should be used for pathogenic variant detection in patients with suspected genetic muscle diseases, focusing first on the most common disease genes described here, and subsequently in rarer and newly characterized disease genes.

}, keywords = {Anoctamins, Exome, Glucosyltransferases, Humans, Muscular Dystrophies, Limb-Girdle, Whole Exome Sequencing}, issn = {1530-0366}, doi = {10.1038/s41436-020-0840-3}, author = {Topf, Ana and Johnson, Katherine and Bates, Adam and Phillips, Lauren and Chao, Katherine R and England, Eleina M and Laricchia, Kristen M and Mullen, Thomas and Valkanas, Elise and Xu, Liwen and Bertoli, Marta and Blain, Alison and Casas{\'u}s, Ana B and Duff, Jennifer and Mroczek, Magdalena and Specht, Sabine and Lek, Monkol and Ensini, Monica and MacArthur, Daniel G and Straub, Volker} } @article {451, title = {Congenital Titinopathy: Comprehensive characterization and pathogenic insights.}, journal = {Ann Neurol}, volume = {83}, year = {2018}, month = {2018 Jun}, pages = {1105-1124}, abstract = {

OBJECTIVE: Comprehensive clinical characterization of congenital titinopathy to facilitate diagnosis and management of this important emerging disorder.

METHODS: Using massively parallel sequencing we identified 30 patients from 27 families with 2 pathogenic nonsense, frameshift and/or splice site TTN mutations in trans. We then undertook a detailed analysis of the clinical, histopathological and imaging features of these patients.

RESULTS: All patients had prenatal or early onset hypotonia and/or congenital contractures. None had ophthalmoplegia. Scoliosis and respiratory insufficiency typically developed early and progressed rapidly, whereas limb weakness was often slowly progressive, and usually did not prevent independent walking. Cardiac involvement was present in 46\% of patients. Relatives of 2 patients had dilated cardiomyopathy. Creatine kinase levels were normal to moderately elevated. Increased fiber size variation, internalized nuclei and cores were common histopathological abnormalities. Cap-like regions, whorled or ring fibers, and mitochondrial accumulations were also observed. Muscle magnetic resonance imaging showed gluteal, hamstring and calf muscle involvement. Western blot analysis showed a near-normal sized titin protein in all samples. The presence of 2 mutations predicted to impact both N2BA and N2B cardiac isoforms appeared to be associated with greatest risk of cardiac involvement. One-third of patients had 1 mutation predicted to impact exons present in fetal skeletal muscle, but not included within the mature skeletal muscle isoform transcript. This strongly suggests developmental isoforms are involved in the pathogenesis of this congenital/early onset disorder.

INTERPRETATION: This detailed clinical reference dataset will greatly facilitate diagnostic confirmation and management of patients, and has provided important insights into disease pathogenesis. Ann Neurol 2018;83:1105-1124.

}, issn = {1531-8249}, doi = {10.1002/ana.25241}, author = {Oates, Emily C and Jones, Kristi J and Donkervoort, Sandra and Charlton, Amanda and Brammah, Susan and Smith, John E and Ware, James S and Yau, Kyle S and Swanson, Lindsay C and Whiffin, Nicola and Peduto, Anthony J and Bournazos, Adam and Waddell, Leigh B and Farrar, Michelle A and Sampaio, Hugo A and Teoh, Hooi Ling and Lamont, Phillipa J and Mowat, David and Fitzsimons, Robin B and Corbett, Alastair J and Ryan, Monique M and O{\textquoteright}Grady, Gina L and Sandaradura, Sarah A and Ghaoui, Roula and Joshi, Himanshu and Marshall, Jamie L and Nolan, Melinda A and Kaur, Simranpreet and Punetha, Jaya and Topf, Ana and Harris, Elizabeth and Bakshi, Madhura and Genetti, Casie A and Marttila, Minttu and Werlauff, Ulla and Streichenberger, Nathalie and Pestronk, Alan and Mazanti, Ingrid and Pinner, Jason R and Vuillerot, Carole and Grosmann, Carla and Camacho, Ana and Mohassel, Payam and Leach, Meganne E and Foley, A Reghan and Bharucha-Goebel, Diana and Collins, James and Connolly, Anne M and Gilbreath, Heather R and Iannaccone, Susan T and Castro, Diana and Cummings, Beryl B and Webster, Richard I and Lazaro, Le{\"\i}la and Vissing, John and Coppens, Sandra and Deconinck, Nicolas and Luk, Ho-Ming and Thomas, Neil H and Foulds, Nicola C and Illingworth, Marjorie A and Ellard, Sian and McLean, Catriona A and Phadke, Rahul and Ravenscroft, Gianina and Witting, Nanna and Hackman, Peter and Richard, Isabelle and Cooper, Sandra T and Kamsteeg, Erik-Jan and Hoffman, Eric P and Bushby, Kate and Straub, Volker and Udd, Bjarne and Ferreiro, Ana and North, Kathryn N and Clarke, Nigel F and Lek, Monkol and Beggs, Alan H and B{\"o}nnemann, Carsten G and MacArthur, Daniel G and Granzier, Henk and Davis, Mark R and Laing, Nigel G} } @article {487, title = {Detection of variants in dystroglycanopathy-associated genes through the application of targeted whole-exome sequencing analysis to a large cohort of patients with unexplained limb-girdle muscle weakness.}, journal = {Skelet Muscle}, volume = {8}, year = {2018}, month = {2018 07 30}, pages = {23}, abstract = {

BACKGROUND: Dystroglycanopathies are a clinically and genetically heterogeneous group of disorders that are typically characterised by limb-girdle muscle weakness. Mutations in 18 different genes have been associated with dystroglycanopathies, the encoded proteins of which typically modulate the binding of α-dystroglycan to extracellular matrix ligands by altering its glycosylation. This results in a disruption of the structural integrity of the myocyte, ultimately leading to muscle degeneration.

METHODS: Deep phenotypic information was gathered using the PhenoTips online software for 1001 patients with unexplained limb-girdle muscle weakness from 43 different centres across 21 European and Middle Eastern countries. Whole-exome sequencing with at least 250~ng DNA was completed using an Illumina exome capture and a 38~Mb baited target. Genes known to be associated with dystroglycanopathies were analysed for disease-causing variants.

RESULTS: Suspected pathogenic variants were detected in DPM3, ISPD, POMT1 and FKTN in one patient each, in POMK in two patients, in GMPPB in three patients, in FKRP in eight patients and in POMT2 in ten patients. This indicated a frequency of 2.7\% for the disease group within the cohort of 1001 patients with unexplained limb-girdle muscle weakness. The phenotypes of the 27 patients were highly variable, yet with a fundamental presentation of proximal muscle weakness and elevated serum creatine kinase.

CONCLUSIONS: Overall, we have identified 27 patients with suspected pathogenic variants in dystroglycanopathy-associated genes. We present evidence for the genetic and phenotypic diversity of the dystroglycanopathies as a disease group, while also highlighting the advantage of incorporating next-generation sequencing into the diagnostic pathway of rare diseases.

}, keywords = {Adolescent, Adult, Aged, Aged, 80 and over, Child, Child, Preschool, Dystroglycans, Female, Genetic Predisposition to Disease, Genetic Variation, Glycosylation, Heterozygote, Homozygote, Humans, Male, Middle Aged, Muscle Proteins, Muscular Dystrophies, Limb-Girdle, Mutation, Phenotype, Whole Exome Sequencing, Young Adult}, issn = {2044-5040}, doi = {10.1186/s13395-018-0170-1}, author = {Johnson, Katherine and Bertoli, Marta and Phillips, Lauren and Topf, Ana and Van den Bergh, Peter and Vissing, John and Witting, Nanna and Nafissi, Shahriar and Jamal-Omidi, Shirin and {\L}usakowska, Anna and Kostera-Pruszczyk, Anna and Potulska-Chromik, Anna and Deconinck, Nicolas and Wallgren-Pettersson, Carina and Strang-Karlsson, Sonja and Colomer, Jaume and Claeys, Kristl G and De Ridder, Willem and Baets, Jonathan and von der Hagen, Maja and Fern{\'a}ndez-Torr{\'o}n, Roberto and Zulaica Ijurco, Miren and Espinal Valencia, Juan Bautista and Hahn, Andreas and Durmus, Hacer and Willis, Tracey and Xu, Liwen and Valkanas, Elise and Mullen, Thomas E and Lek, Monkol and MacArthur, Daniel G and Straub, Volker} } @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 {421, title = {Identification of GAA variants through whole exome sequencing targeted to a cohort of 606 patients with unexplained limb-girdle muscle weakness.}, journal = {Orphanet J Rare Dis}, volume = {12}, year = {2017}, month = {2017 11 17}, pages = {173}, abstract = {

BACKGROUND: Late-onset Pompe disease is a rare genetic neuromuscular disorder caused by a primary deficiency of α-glucosidase and the associated accumulation of glycogen in lysosomal vacuoles. The deficiency of α-glucosidase can often be detected using an inexpensive and readily accessible dried blood spot test when Pompe disease is suspected. Like several neuromuscular disorders, Pompe disease typically presents with progressive weakness of limb-girdle muscles and respiratory insufficiency. Due to the phenotypic heterogeneity of these disorders, however, it is often difficult for clinicians to reach a diagnosis for patients with Pompe disease. Six hundred and six patients from a European population were recruited onto our study. Inclusion criteria stipulated that index cases must present with limb-girdle weakness or elevated serum creatine kinase activity. Whole exome sequencing with at least 250~ng DNA was completed using an Illumina exome capture and a 38~Mb baited target. A panel of 169 candidate genes for limb-girdle weakness was analysed for disease-causing variants.

RESULTS: A total of 35 variants within GAA were detected. Ten distinct variants in eight unrelated index cases (and four siblings not sequenced in our study) were considered disease-causing, with the patients presenting with heterogeneous phenotypes. The eight unrelated individuals were compound heterozygotes for two variants. Six patients carried the intronic splice site c.-13~T > G transversion and two of the six patients also carried the exonic p.Glu176ArgfsTer45 frameshift. Four of the ten variants were novel in their association with Pompe disease.

CONCLUSIONS: Here, we highlight the advantage of using whole exome sequencing as a tool for detecting, diagnosing and treating patients with rare, clinically variable genetic disorders.

}, keywords = {Adolescent, Adult, Aged, Aged, 80 and over, alpha-Glucosidases, Child, Child, Preschool, Cohort Studies, Female, Genetic Variation, Glycogen Storage Disease Type II, Humans, Male, Middle Aged, Muscle Weakness, Muscular Dystrophies, Limb-Girdle, Whole Exome Sequencing, Young Adult}, issn = {1750-1172}, doi = {10.1186/s13023-017-0722-1}, author = {Johnson, Katherine and Topf, Ana and Bertoli, Marta and Phillips, Lauren and Claeys, Kristl G and Stojanovic, Vidosava Rakocevic and Peri{\'c}, Stojan and Hahn, Andreas and Maddison, Paul and Akay, Ela and Bastian, Alexandra E and {\L}usakowska, Anna and Kostera-Pruszczyk, Anna and Lek, Monkol and Xu, Liwen and MacArthur, Daniel G and Straub, Volker} } @article {364, title = {Improving genetic diagnosis in Mendelian disease with transcriptome sequencing.}, journal = {Sci Transl Med}, volume = {9}, year = {2017}, month = {2017 04 19}, abstract = {

Exome and whole-genome sequencing are becoming increasingly routine approaches in Mendelian disease diagnosis. Despite their success, the current diagnostic rate for genomic analyses across a variety of rare diseases is approximately 25 to 50\%. We explore the utility of transcriptome sequencing [RNA sequencing (RNA-seq)] as a complementary diagnostic tool in a cohort of 50 patients with genetically undiagnosed rare muscle disorders. We describe an integrated approach to analyze patient muscle RNA-seq, leveraging an analysis framework focused on the detection of transcript-level changes that are unique to the patient compared to more than 180 control skeletal muscle samples. We demonstrate the power of RNA-seq to validate candidate splice-disrupting mutations and to identify splice-altering variants in both exonic and deep intronic regions, yielding an overall diagnosis rate of 35\%. We also report the discovery of a highly recurrent de novo intronic mutation in that results in a dominantly acting splice-gain event, disrupting the critical glycine repeat motif of the triple helical domain. We identify this pathogenic variant in a total of 27 genetically unsolved patients in an external collagen VI-like dystrophy cohort, thus explaining approximately 25\% of patients clinically suggestive of having collagen VI dystrophy in whom prior genetic analysis is negative. Overall, this study represents a large systematic application of transcriptome sequencing to rare disease diagnosis and highlights its utility for the detection and interpretation of variants missed by current standard diagnostic approaches.

}, keywords = {Collagen Type VI, High-Throughput Nucleotide Sequencing, Humans, Muscular Diseases, Mutation, Transcriptome}, issn = {1946-6242}, doi = {10.1126/scitranslmed.aal5209}, author = {Cummings, Beryl B and Marshall, Jamie L and Tukiainen, Taru and Lek, Monkol and Donkervoort, Sandra and Foley, A Reghan and Bolduc, Veronique and Waddell, Leigh B and Sandaradura, Sarah A and O{\textquoteright}Grady, Gina L and Estrella, Elicia and Reddy, Hemakumar M and Zhao, Fengmei and Weisburd, Ben and Karczewski, Konrad J and O{\textquoteright}Donnell-Luria, Anne H and Birnbaum, Daniel and Sarkozy, Anna and Hu, Ying and Gonorazky, Hernan and Claeys, Kristl and Joshi, Himanshu and Bournazos, Adam and Oates, Emily C and Ghaoui, Roula and Davis, Mark R and Laing, Nigel G and Topf, Ana and Kang, Peter B and Beggs, Alan H and North, Kathryn N and Straub, Volker and Dowling, James J and Muntoni, Francesco and Clarke, Nigel F and Cooper, Sandra T and B{\"o}nnemann, Carsten G and MacArthur, Daniel G} }