Publications by authors named "Roula Ghaoui"

17 Publications

  • Page 1 of 1

Expanding the disease phenotype of ADSSL1-associated myopathy in non-Korean patients.

Neuromuscul Disord 2020 04 14;30(4):310-314. Epub 2020 Feb 14.

John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Central Parkway, Newcastle upon Tyne NE1 3BZ, UK. Electronic address:

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.
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http://dx.doi.org/10.1016/j.nmd.2020.02.006DOI Listing
April 2020

Pathogenic Abnormal Splicing Due to Intronic Deletions that Induce Biophysical Space Constraint for Spliceosome Assembly.

Am J Hum Genet 2019 09 22;105(3):573-587. Epub 2019 Aug 22.

Kids Neuroscience Centre, Kids Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia; Discipline of Child and Adolescent Health, Sydney Medical School, University of Sydney, Sydney, NSW 2006, Australia; The Children's Medical Research Institute, 214 Hawkesbury Road, Sydney, NSW 2145, Australia. Electronic address:

A precise genetic diagnosis is the single most important step for families with genetic disorders to enable personalized and preventative medicine. In addition to genetic variants in coding regions (exons) that can change a protein sequence, abnormal pre-mRNA splicing can be devastating for the encoded protein, inducing a frameshift or in-frame deletion/insertion of multiple residues. Non-coding variants that disrupt splicing are extremely challenging to identify. Stemming from an initial clinical discovery in two index Australian families, we define 25 families with genetic disorders caused by a class of pathogenic non-coding splice variant due to intronic deletions. These pathogenic intronic deletions spare all consensus splice motifs, though they critically shorten the minimal distance between the 5' splice-site (5'SS) and branchpoint. The mechanistic basis for abnormal splicing is due to biophysical constraint precluding U1/U2 spliceosome assembly, which stalls in A-complexes (that bridge the 5'SS and branchpoint). Substitution of deleted nucleotides with non-specific sequences restores spliceosome assembly and normal splicing, arguing against loss of an intronic element as the primary causal basis. Incremental lengthening of 5'SS-branchpoint length in our index EMD case subject defines 45-47 nt as the critical elongation enabling (inefficient) spliceosome assembly for EMD intron 5. The 5'SS-branchpoint space constraint mechanism, not currently factored by genomic informatics pipelines, is relevant to diagnosis and precision medicine across the breadth of Mendelian disorders and cancer genomics.
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http://dx.doi.org/10.1016/j.ajhg.2019.07.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6731365PMC
September 2019

Recessive DES cardio/myopathy without myofibrillar aggregates: intronic splice variant silences one allele leaving only missense L190P-desmin.

Eur J Hum Genet 2019 08 25;27(8):1267-1273. Epub 2019 Apr 25.

Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW, 2145, Australia.

We establish autosomal recessive DES variants p.(Leu190Pro) and a deep intronic splice variant causing inclusion of a frameshift-inducing artificial exon/intronic fragment, as the likely cause of myopathy with cardiac involvement in female siblings. Both sisters presented in their twenties with slowly progressive limb girdle weakness, severe systolic dysfunction, and progressive, severe respiratory weakness. Desmin is an intermediate filament protein typically associated with autosomal dominant myofibrillar myopathy with cardiac involvement. However a few rare cases of autosomal recessive desminopathy are reported. In this family, a paternal missense p.(Leu190Pro) variant was viewed unlikely to be causative of autosomal dominant desminopathy, as the father and brothers carrying this variant were clinically unaffected. Clinical fit with a DES-related myopathy encouraged closer scrutiny of all DES variants, identifying a maternal deep intronic variant within intron-7, predicted to create a cryptic splice site, which segregated with disease. RNA sequencing and studies of muscle cDNA confirmed the deep intronic variant caused aberrant splicing of an artificial exon/intronic fragment into maternal DES mRNA transcripts, encoding a premature termination codon, and potently activating nonsense-mediate decay (92% paternal DES transcripts, 8% maternal). Western blot showed 60-75% reduction in desmin levels, likely comprised only of missense p.(Leu190Pro) desmin. Biopsy showed fibre size variation with increased central nuclei. Electron microscopy showed extensive myofibrillar disarray, duplication of the basal lamina, but no inclusions or aggregates. This study expands the phenotypic spectrum of recessive DES cardio/myopathy, and emphasizes the continuing importance of muscle biopsy for functional genomics pursuit of 'tricky' variants in neuromuscular conditions.
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http://dx.doi.org/10.1038/s41431-019-0393-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6777463PMC
August 2019

Genetic mimics of cerebral palsy.

Mov Disord 2019 05 26;34(5):625-636. Epub 2019 Mar 26.

Department of Neurogenetics, Kolling Institute, Royal North Shore Hospital and University of Sydney, St Leonards, NSW, Australia.

The term "cerebral palsy mimic" is used to describe a number of neurogenetic disorders that may present with motor symptoms in early childhood, resulting in a misdiagnosis of cerebral palsy. Cerebral palsy describes a heterogeneous group of neurodevelopmental disorders characterized by onset in infancy or early childhood of motor symptoms (including hypotonia, spasticity, dystonia, and chorea), often accompanied by developmental delay. The primary etiology of a cerebral palsy syndrome should always be identified if possible. This is particularly important in the case of genetic or metabolic disorders that have specific disease-modifying treatment. In this article, we discuss clinical features that should alert the clinician to the possibility of a cerebral palsy mimic, provide a practical framework for selecting and interpreting neuroimaging, biochemical, and genetic investigations, and highlight selected conditions that may present with predominant spasticity, dystonia/chorea, and ataxia. Making a precise diagnosis of a genetic disorder has important implications for treatment, and for advising the family regarding prognosis and genetic counseling. © 2019 International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.27655DOI Listing
May 2019

Congenital Titinopathy: Comprehensive characterization and pathogenic insights.

Ann Neurol 2018 06;83(6):1105-1124

Harry Perkins Institute, University of Western Australia, Nedlands, Western Australia, Australia.

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.
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http://dx.doi.org/10.1002/ana.25241DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105519PMC
June 2018

Movement disorders in mitochondrial disease.

J Neurol 2018 May 6;265(5):1230-1240. Epub 2018 Jan 6.

Department of Neurogenetics, Kolling Institute, Royal North Shore Hospital, University of Sydney, Sydney, NSW, Australia.

Mitochondrial disease presents with a wide spectrum of clinical manifestations that may appear at any age and cause multisystem dysfunction. A broad spectrum of movement disorders can manifest in mitochondrial diseases including ataxia, Parkinsonism, myoclonus, dystonia, choreoathetosis, spasticity, tremor, tic disorders and restless legs syndrome. There is marked heterogeneity of movement disorder phenotypes, even in patients with the same genetic mutation. Moreover, the advent of new technologies, such as next-generation sequencing, is likely to identify novel causative genes, expand the phenotype of known disease genes and improve the genetic diagnosis in these patients. Identification of the underlying genetic basis of the movement disorder is also a crucial step to allow for targeted therapies to be implemented as well as provide the basis for a better understanding of the molecular pathophysiology of the disease process. The aim of this review is to discuss the spectrum of movement disorders associated with mitochondrial disease.
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http://dx.doi.org/10.1007/s00415-017-8722-6DOI Listing
May 2018

A 'limb-girdle muscular dystrophy' responsive to asthma therapy.

Pract Neurol 2017 Aug 22;17(4):327-331. Epub 2017 Apr 22.

Department of Neurology, Auckland City Hospital, Auckland, New Zealand.

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http://dx.doi.org/10.1136/practneurol-2017-001598DOI Listing
August 2017

Improving genetic diagnosis in Mendelian disease with transcriptome sequencing.

Sci Transl Med 2017 04;9(386)

Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA.

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.
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http://dx.doi.org/10.1126/scitranslmed.aal5209DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5548421PMC
April 2017

Targeted Re-Sequencing Emulsion PCR Panel for Myopathies: Results in 94 Cases.

J Neuromuscul Dis 2016 05;3(2):209-225

Research Center for Genetic Medicine, Children's National Medical Center, Washington DC, USA.

Background: Molecular diagnostics in the genetic myopathies often requires testing of the largest and most complex transcript units in the human genome (DMD, TTN, NEB). Iteratively targeting single genes for sequencing has traditionally entailed high costs and long turnaround times. Exome sequencing has begun to supplant single targeted genes, but there are concerns regarding coverage and needed depth of the very large and complex genes that frequently cause myopathies.

Objective: To evaluate efficiency of next-generation sequencing technologies to provide molecular diagnostics for patients with previously undiagnosed myopathies.

Methods: We tested a targeted re-sequencing approach, using a 45 gene emulsion PCR myopathy panel, with subsequent sequencing on the Illumina platform in 94 undiagnosed patients. We compared the targeted re-sequencing approach to exome sequencing for 10 of these patients studied.

Results: We detected likely pathogenic mutations in 33 out of 94 patients with a molecular diagnostic rate of approximately 35%. The remaining patients showed variants of unknown significance (35/94 patients) or no mutations detected in the 45 genes tested (26/94 patients). Mutation detection rates for targeted re-sequencing vs. whole exome were similar in both methods; however exome sequencing showed better distribution of reads and fewer exon dropouts.

Conclusions: Given that costs of highly parallel re-sequencing and whole exome sequencing are similar, and that exome sequencing now takes considerably less laboratory processing time than targeted re-sequencing, we recommend exome sequencing as the standard approach for molecular diagnostics of myopathies.
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http://dx.doi.org/10.3233/JND-160151DOI Listing
May 2016

TOR1AIP1 as a cause of cardiac failure and recessive limb-girdle muscular dystrophy.

Neuromuscul Disord 2016 08 24;26(8):500-3. Epub 2016 May 24.

Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, NSW 2145, Australia; Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW 2006, Australia. Electronic address:

TorsinA-interacting protein 1 (TOR1AIP1) gene is a novel gene that has recently been described to cause limb-girdle muscular dystrophy (LGMD) with mild dilated cardiomyopathy. We report a family with mutations in TOR1AIP1 where the striking clinical feature is severe cardiac failure requiring cardiac transplant in two siblings, in addition to musculoskeletal weakness and muscular dystrophy. We demonstrate an absence of TOR1AIP1 protein expression in cardiac and skeletal muscles of affected siblings. We expand the phenotype of this gene to demonstrate the cardiac involvement and the importance of cardiac surveillance in patients with mutations in TOR1AIP1.
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http://dx.doi.org/10.1016/j.nmd.2016.05.013DOI Listing
August 2016

Diagnosis and etiology of congenital muscular dystrophy: We are halfway there.

Ann Neurol 2016 07 25;80(1):101-11. Epub 2016 May 25.

Institute for Neuroscience and Muscle Research, Kids Research Institute, Children's Hospital at Westmead, Westmead, New South Wales, Australia.

Objective: To evaluate the diagnostic outcomes in a large cohort of congenital muscular dystrophy (CMD) patients using traditional and next generation sequencing (NGS) technologies.

Methods: A total of 123 CMD patients were investigated using the traditional approaches of histology, immunohistochemical analysis of muscle biopsy, and candidate gene sequencing. Undiagnosed patients available for further testing were investigated using NGS.

Results: Muscle biopsy and immunohistochemical analysis found deficiencies of laminin α2, α-dystroglycan, or collagen VI in 50% of patients. Candidate gene sequencing and chromosomal microarray established a genetic diagnosis in 32% (39 of 123). Of 85 patients presenting in the past 20 years, 28 of 51 who lacked a confirmed genetic diagnosis (55%) consented to NGS studies, leading to confirmed diagnoses in a further 11 patients. Using the combination of approaches, a confirmed genetic diagnosis was achieved in 51% (43 of 85). The diagnoses within the cohort were heterogeneous. Forty-five of 59 probands with confirmed or probable diagnoses had variants in genes known to cause CMD (76%), and 11 of 59 (19%) had variants in genes associated with congenital myopathies, reflecting overlapping features of these conditions. One patient had a congenital myasthenic syndrome, and 2 had microdeletions. Within the cohort, 5 patients had variants in novel (PIGY and GMPPB) or recently published genes (GFPT1 and MICU1), and 7 had variants in TTN or RYR1, large genes that are technically difficult to Sanger sequence.

Interpretation: These data support NGS as a first-line tool for genetic evaluation of patients with a clinical phenotype suggestive of CMD, with muscle biopsy reserved as a second-tier investigation. Ann Neurol 2016;80:101-111.
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http://dx.doi.org/10.1002/ana.24687DOI Listing
July 2016

Prominent scapulae mimicking an inherited myopathy expands the phenotype of CHD7-related disease.

Eur J Hum Genet 2016 08 27;24(8):1216-9. Epub 2016 Jan 27.

Institute for Neuroscience and Muscle Research, Kids Research Institute, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.

CHD7 variants are a well-established cause of CHARGE syndrome, a disabling multi-system malformation disorder that is often associated with deafness, visual impairment and intellectual disability. Less severe forms of CHD7-related disease are known to exist, but the full spectrum of phenotypes remains uncertain. We identified a de novo missense variant in CHD7 in a family presenting with musculoskeletal abnormalities as the main manifestation of CHD7-related disease, representing a new phenotype. The proband presented with prominent scapulae, mild shoulder girdle weakness and only subtle dysmorphic features. Investigation revealed hypoplasia of the trapezius and sternocleidomastoid muscles and semicircular canal defects, but he did not fulfill diagnostic criteria for CHARGE syndrome. Although the shoulders are often sloping and anteverted in CHARGE syndrome, the underlying neuromuscular cause has never been investigated. This report expands the phenotypes associated with CHD7 mutations to include a musculoskeletal presentation, with hypoplasia of the shoulder and neck muscles. CHD7 should be considered in patients presenting in childhood with stable scapular winging, particularly if accompanied by dysmorphic features and balance difficulties.
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http://dx.doi.org/10.1038/ejhg.2015.276DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4970689PMC
August 2016

Mutations in HSPB8 causing a new phenotype of distal myopathy and motor neuropathy.

Neurology 2016 Jan 30;86(4):391-8. Epub 2015 Dec 30.

From the Institute for Neuroscience and Muscle Research (R.G., L.W., S.K., N.C.), Kids Research Institute, Children's Hospital at Westmead & University of Sydney, Australia; Neuromuscular Research Center, Department of Neurology (J.P., S.P., M.L., B.U.), and Department of Pathology, Fimlab Laboratories (S.H.), Tampere University Hospital and University of Tampere, Finland; Department of Pathology (J.B.), Royal North Shore Hospital, Sydney, Australia; Broad Institute of Harvard and MIT (M.L., D.G.M.), Cambridge, MA; Western Australian Neurosciences Research Institute (M.N.), University of Western Australia, Perth; Folkhälsan Institute of Genetics and Department of Medical Genetics (A.E., P.H., P.H.-J., A.V., B.U.), University of Helsinki, Finland; Department of Neurogenetics (R.L.D., C.Y., C.M.S.), Kolling Institute, Royal North Shore Hospital and University of Sydney; Murdoch Children's Research Institute (K.N.), The Royal Children's Hospital, Melbourne, Australia; Analytic and Translational Genetics Unit (M.L., D.G.M.), Massachusetts General Hospital, Boston; and Department of Neurology (B.U.), Vaasa Central Hospital, Finland.

Objective: To report novel disease and pathology due to HSPB8 mutations in 2 families with autosomal dominant distal neuromuscular disease showing both myofibrillar and rimmed vacuolar myopathy together with neurogenic changes.

Methods: We performed whole-exome sequencing (WES) in tandem with linkage analysis and candidate gene approach as well as targeted next-generation sequencing (tNGS) to identify causative mutations in 2 families with dominant rimmed vacuolar myopathy and a motor neuropathy. Pathogenic variants and familial segregation were confirmed using Sanger sequencing.

Results: WES and tNGS identified a heterozygous change in HSPB8 in both families: c.421A > G p.K141E in family 1 and c.151insC p.P173SfsX43 in family 2. Affected patients had a distal myopathy that showed myofibrillar aggregates and rimmed vacuoles combined with a clear neurogenic component both on biopsy and neurophysiologic studies. MRI of lower limb muscles demonstrated diffuse tissue changes early in the disease stage progressing later to fatty replacement typical of a myopathy.

Conclusion: We expand the understanding of disease mechanisms, tissue involvement, and phenotypic outcome of HSPB8 mutations. HSPB8 is part of the chaperone-assisted selective autophagy (CASA) complex previously only associated with Charcot-Marie-Tooth type 2L (OMIM 60673) and distal hereditary motor neuronopathy type IIa. However, we now demonstrate that patients can develop a myopathy with histologic features of myofibrillar myopathy with aggregates and rimmed vacuoles, similar to the pathology in myopathies due to gene defects in other compounds of the CASA complex such as BAG3 and DNAJB6 after developing the early neurogenic effects.
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http://dx.doi.org/10.1212/WNL.0000000000002324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4776089PMC
January 2016

Use of Whole-Exome Sequencing for Diagnosis of Limb-Girdle Muscular Dystrophy: Outcomes and Lessons Learned.

JAMA Neurol 2015 Dec;72(12):1424-32

Institute for Neuroscience and Muscle Research, Kid's Research Institute, Children's Hospital at Westmead, Sydney, New South Wales, Australia2Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, Sydney, New South Wales.

Importance: To our knowledge, the efficacy of transferring next-generation sequencing from a research setting to neuromuscular clinics has never been evaluated.

Objective: To translate whole-exome sequencing (WES) to clinical practice for the genetic diagnosis of a large cohort of patients with limb-girdle muscular dystrophy (LGMD) for whom protein-based analyses and targeted Sanger sequencing failed to identify the genetic cause of their disorder.

Design, Setting, And Participants: We performed WES on 60 families with LGMDs (100 exomes). Data analysis was performed between January 6 and December 19, 2014, using the xBrowse bioinformatics interface (Broad Institute). Patients with LGMD were ascertained retrospectively through the Institute for Neuroscience and Muscle Research Biospecimen Bank between 2006 and 2014. Enrolled patients had been extensively investigated via protein studies and candidate gene sequencing and remained undiagnosed. Patients presented with more than 2 years of muscle weakness and with dystrophic or myopathic changes present in muscle biopsy specimens.

Main Outcomes And Measures: The diagnostic rate of LGMD in Australia and the relative frequencies of the different LGMD subtypes. Our central goals were to improve the genetic diagnosis of LGMD, investigate whether the WES platform provides adequate coverage of known LGMD-related genes, and identify new LGMD-related genes.

Results: With WES, we identified likely pathogenic mutations in known myopathy genes for 27 of 60 families. Twelve families had mutations in known LGMD-related genes. However, 15 families had variants in disease-related genes not typically associated with LGMD, highlighting the clinical overlap between LGMD and other myopathies. Common causes of phenotypic overlap were due to mutations in congenital muscular dystrophy-related genes (4 families) and collagen myopathy-related genes (4 families). Less common myopathies included metabolic myopathy (2 families), congenital myasthenic syndrome (DOK7), congenital myopathy (ACTA1), tubular aggregate myopathy (STIM1), myofibrillar myopathy (FLNC), and mutation of CHD7, usually associated with the CHARGE syndrome. Inclusion of family members increased the diagnostic efficacy of WES, with a diagnostic rate of 60% for "trios" (an affected proband with both parents) vs 40% for single probands. A follow-up screening of patients whose conditions were undiagnosed on a targeted neuromuscular disease-related gene panel did not improve our diagnostic yield.

Conclusions And Relevance: With WES, we achieved a diagnostic success rate of 45.0% in our difficult-to-diagnose cohort of patients with LGMD. We expand the clinical phenotypes associated with known myopathy genes, and we stress the importance of accurate clinical examination and histopathological results for interpretation of WES, with many diagnoses requiring follow-up review and ancillary investigations of biopsy specimens or serum samples.
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http://dx.doi.org/10.1001/jamaneurol.2015.2274DOI Listing
December 2015

Expanding the phenotype of GMPPB mutations.

Brain 2015 Apr 12;138(Pt 4):836-44. Epub 2015 Feb 12.

1 Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, Perth, WA, Australia.

Dystroglycanopathies are a heterogeneous group of diseases with a broad phenotypic spectrum ranging from severe disorders with congenital muscle weakness, eye and brain structural abnormalities and intellectual delay to adult-onset limb-girdle muscular dystrophies without mental retardation. Most frequently the disease onset is congenital or during childhood. The exception is FKRP mutations, in which adult onset is a common presentation. Here we report eight patients from five non-consanguineous families where next generation sequencing identified mutations in the GMPPB gene. Six patients presented as an adult or adolescent-onset limb-girdle muscular dystrophy, one presented with isolated episodes of rhabdomyolysis, and one as a congenital muscular dystrophy. This report expands the phenotypic spectrum of GMPPB mutations to include limb-girdle muscular dystrophies with adult onset with or without intellectual disability, or isolated rhabdomyolysis.
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http://dx.doi.org/10.1093/brain/awv013DOI Listing
April 2015

Axonal excitability in primary amyloidotic neuropathy.

Muscle Nerve 2015 Mar 16;51(3):443-5. Epub 2015 Jan 16.

Department of Neurology and Clinical Neurophysiology, Royal North Shore Hospital, Reserve Road, St Leonards, New South Wales, 2065, Australia.

Introduction: Acquired and hereditary amyloidosis can cause peripheral neuropathy, but the mechanisms by which this occurs have not been established. Threshold tracking techniques allow in vivo assessment of the properties of the axonal membrane and may shed light on pathogenetic mechanisms underlying neuropathic disorders.

Methods: We studied 10 subjects with primary amyloidosis using conventional nerve conduction studies and quantitative sensory, autonomic, and axonal excitability testing of median motor and sensory fibers.

Results: As expected, subjects with amyloidosis had evidence of small- and large-fiber neuropathy on conventional testing. There was no significant difference in axonal excitability between subjects and controls apart from the stimulus required to activate sensory fibers.

Conclusions: Amyloid-related neuropathy does not produce a change in membrane potential as either a primary or secondary event. This suggests that ischemia and axonal compression are unlikely mechanisms for the neuropathy.
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http://dx.doi.org/10.1002/mus.24508DOI Listing
March 2015

UDP-glucuronosyltransferase-dependent bioactivation of clofibric acid to a DNA-damaging intermediate in mouse hepatocytes.

Chem Biol Interact 2003 May;145(2):201-11

Molecular Toxicology Research Group, Department of Clinical and Experimental Pharmacology, University of Adelaide, Adelaide, SA 5005, Australia.

Glucuronidation of a number of carboxyl-containing drugs generates reactive acyl glucuronide metabolites. These electrophilic species alkylate cell proteins and may be implicated in the pathogenesis of a number of toxic syndromes seen in patients receiving the parent aglycones. Whether acyl glucuronides also attack nuclear DNA is unknown, although the acyl glucuronide formed from clofibric acid was recently found to decrease the transfection efficiency of phage DNA and generate strand breaks in plasmid DNA in vitro. To determine if such a DNA damage occurs within a cellular environment, the comet assay (i.e. single-cell gel electrophoresis) was used to detect DNA lesions in the nuclear genome of isolated mouse hepatocytes cultured with clofibric acid. Overnight exposure to 50 microM and higher concentrations of clofibric acid produced concentration-dependent increases in the comet areas of hepatocyte nuclei, with 1 mM clofibrate producing a 3.6-fold elevation over controls. These effects closely coincided with culture medium concentrations of the glucuronide metabolite formed from clofibric acid, 1-O-beta-clofibryl glucuronide. Consistent with a role for glucuronidation in the DNA damage observed, the glucuronidation inhibitor borneol diminished glucuronide formation from 100 microM clofibrate by 98% and returned comet areas to baseline levels. Collectively, these results suggest that the acyl glucuronide formed from clofibric acid is capable of migrating from its site of formation within the endoplasmic reticulum to generate strand nicks in nuclear DNA.
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http://dx.doi.org/10.1016/s0009-2797(02)00253-3DOI Listing
May 2003