@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 {17, title = {The sensitivity of exome sequencing in identifying pathogenic mutations for LGMD in the United States.}, journal = {J Hum Genet}, volume = {62}, year = {2017}, month = {2017 Feb}, pages = {243-252}, abstract = {

The current study characterizes a cohort of limb-girdle muscular dystrophy (LGMD) in the United States using whole-exome sequencing. Fifty-five families affected by LGMD were recruited using an institutionally approved protocol. Exome sequencing was performed on probands and selected parental samples. Pathogenic mutations and cosegregation patterns were confirmed by Sanger sequencing. Twenty-two families (40\%) had novel and previously reported pathogenic mutations, primarily in LGMD genes, and also in genes for Duchenne muscular dystrophy, facioscapulohumeral muscular dystrophy, congenital myopathy, myofibrillar myopathy, inclusion body myopathy and Pompe disease. One family was diagnosed via clinical testing. Dominant mutations were identified in COL6A1, COL6A3, FLNC, LMNA, RYR1, SMCHD1 and VCP, recessive mutations in ANO5, CAPN3, GAA, LAMA2, SGCA and SGCG, and X-linked mutations in DMD. A previously reported variant in DMD was confirmed to be benign. Exome sequencing is a powerful diagnostic tool for LGMD. Despite careful phenotypic screening, pathogenic mutations were found in other muscle disease genes, largely accounting for the increased sensitivity of exome sequencing. Our experience suggests that broad sequencing panels are useful for these analyses because of the phenotypic overlap of many neuromuscular conditions. The confirmation of a benign DMD variant illustrates the potential of exome sequencing to help determine pathogenicity.

}, keywords = {Base Sequence, Distal Myopathies, Exome, Female, Genetic Testing, Glycogen Storage Disease Type II, Humans, Male, Muscular Dystrophies, Limb-Girdle, Muscular Dystrophy, Duchenne, Muscular Dystrophy, Facioscapulohumeral, Mutation, Myopathies, Structural, Congenital, Sequence Analysis, DNA, United States}, issn = {1435-232X}, doi = {10.1038/jhg.2016.116}, author = {Reddy, Hemakumar M and Cho, Kyung-Ah and Lek, Monkol and Estrella, Elicia and Valkanas, Elise and Jones, Michael D and Mitsuhashi, Satomi and Darras, Basil T and Amato, Anthony A and Lidov, Hart Gw and Brownstein, Catherine A and Margulies, David M and Yu, Timothy W and Salih, Mustafa A and Kunkel, Louis M and MacArthur, Daniel G and Kang, Peter B} }