@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 {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 {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} }