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1.  Pontocerebellar hypoplasia type 1 
Neurology  2013;80(5):438-446.
Objectives:
Pontocerebellar hypoplasia with spinal muscular atrophy, also known as PCH1, is a group of autosomal recessive disorders characterized by generalized muscle weakness and global developmental delay commonly resulting in early death. Gene defects had been discovered only in single patients until the recent identification of EXOSC3 mutations in several families with relatively mild course of PCH1. We aim to genetically stratify subjects in a large and well-defined cohort to define the clinical spectrum and genotype–phenotype correlation.
Methods:
We documented clinical, neuroimaging, and morphologic data of 37 subjects from 27 families with PCH1. EXOSC3 gene sequencing was performed in 27 unrelated index patients of mixed ethnicity.
Results:
Biallelic mutations in EXOSC3 were detected in 10 of 27 families (37%). The most common mutation among all ethnic groups was c.395A>C, p.D132A, responsible for 11 (55%) of the 20 mutated alleles and ancestral in origin. The mutation-positive subjects typically presented with normal pregnancy, normal birth measurements, and relative preservation of brainstem and cortical structures. Psychomotor retardation was profound in all patients but lifespan was variable, with 3 subjects surviving beyond the late teens. Abnormal oculomotor function was commonly observed in patients surviving beyond the first year. Major clinical features previously reported in PCH1, including intrauterine abnormalities, postnatal hypoventilation and feeding difficulties, joint contractures, and neonatal death, were rarely observed in mutation-positive infants but were typical among the mutation-negative subjects.
Conclusion:
EXOSC3 mutations account for 30%–40% of patients with PCH1 with variability in survival and clinical severity that is correlated with the genotype.
doi:10.1212/WNL.0b013e31827f0f66
PMCID: PMC3590055  PMID: 23284067
2.  The TREAT-NMD care and trial site registry: an online registry to facilitate clinical research for neuromuscular diseases 
Background
Rare diseases pose many research challenges specific to their scarcity. Advances in potential therapies have made it more important than ever to be able to adequately identify not only patients with particular genotypes (via patient registries) but also the medical professionals who provide care for them at particular specialist centres of expertise and who may be competent to participate in trials. Work within the neuromuscular field provides an example of how this may be achieved.
Methods
This paper describes the development of the TREAT-NMD Care and Trial Site Registry (CTSR), an initiative of an EU-funded Network of Excellence, and its utility in providing an infrastructure for clinical trial feasibility, recruitment, and other studies.
Results
285 CTSR-registered centres, reporting 35,495 neuromuscular patients, are described alongside an analysis of their provision for DMD. Site characteristics vary by country: the average number of DMD patients seen per site in the United States (96) is more than in Germany (25), and paediatric/adult breakdown is also markedly distinct. Over 70% of sites have previous trial experience, with a majority including a Clinical Trials Unit. Most sites also have MLPA diagnostic capability and access to a range of medical specialists. However, in the three countries reporting most sites (US, the UK and Germany), few had access to all core DMD specialists internally. Over 60% of sites did not report any form of transition arrangement.
Conclusions
Registries of care and trial sites have significant utility for research into rare conditions such as neuromuscular diseases, demonstrated by the significant engagement by industry and other researchers with the CTSR. We suggest that this approach may be applicable to other fields needing to identify centres of expertise with the potential to carry out clinical research and engage in clinical trials. Such registries also lend themselves to the developing context of European Reference Networks (ERNs), which seek to build networks of centres of expertise which fit specific criteria, and which may themselves aid the sustainability of such registries. This is particularly the case given the utility of registries such as the CTSR in enabling networks of best-practice care centres.
doi:10.1186/1750-1172-8-171
PMCID: PMC3819466  PMID: 24148153
Rare diseases; Registries; Clinical trials; Trial sites; Care sites; Centres of expertise; CTSR; Reference networks; ERN; CARE-NMD
3.  Prion-like domain mutations in hnRNPs cause multisystem proteinopathy and ALS 
Nature  2013;495(7442):467-473.
Summary
Algorithms designed to identify canonical yeast prions predict that ~250 human proteins, including several RNA-binding proteins associated with neurodegenerative disease, harbor a distinctive prion-like domain (PrLD) enriched in uncharged polar amino acids and glycine. PrLDs in RNA-binding proteins are essential for the assembly of ribonucleoprotein granules. However, the interplay between human PrLD function and disease is not understood. Here, we define pathogenic mutations in PrLDs of hnRNPA2/B1 and hnRNPA1 in families with inherited degeneration affecting muscle, brain, motor neuron and bone, and a case of familial ALS. Wild-type hnRNPA2 and hnRNPA1 display an intrinsic tendency to assemble into self-seeding fibrils, which is exacerbated by the disease mutations. Indeed, the pathogenic mutations strengthen a ‘steric zipper’ motif in the PrLD, which accelerates formation of self-seeding fibrils that cross-seed polymerization of wild-type hnRNP. Importantly, the disease mutations promote excess incorporation of hnRNPA2 and hnRNPA1 into stress granules and drive the formation of cytoplasmic inclusions in animal models that recapitulate the human pathology. Thus, dysregulated polymerization caused by a potent mutant ‘steric zipper’ motif in a PrLD can initiate degenerative disease. Related proteins with PrLDs must be considered candidates for initiating and perhaps propagating proteinopathies of muscle, brain, motor neuron and bone.
doi:10.1038/nature11922
PMCID: PMC3756911  PMID: 23455423
4.  Guidance in Social and Ethical Issues Related to Clinical, Diagnostic Care and Novel Therapies for Hereditary Neuromuscular Rare Diseases: “Translating“ the Translational 
PLoS Currents  2013;5:ecurrents.md.f90b49429fa814bd26c5b22b13d773ec.
Drug trials in children engage with many ethical issues, from drug-related safety concerns to communication with patients and parents, and recruitment and informed consent procedures. This paper addresses the field of neuromuscular disorders where the possibility of genetic, mutation-specific treatments, has added new complexity. Not only must trial design address issues of equity of access, but researchers must also think through the implications of adopting a personalised medicine approach, which requires a precise molecular diagnosis, in addition to other implications of developing orphan drugs. It is against this background of change and complexity that the Project Ethics Council (PEC) was established within the TREAT-NMD EU Network of Excellence. The PEC is a high level advisory group that draws upon the expertise of its interdisciplinary membership which includes clinicians, lawyers, scientists, parents, representatives of patient organisations, social scientists and ethicists. In this paper we describe the establishment and terms of reference of the PEC, give an indication of the range and depth of its work and provide some analysis of the kinds of complex questions encountered. The paper describes how the PEC has responded to substantive ethical issues raised within the TREAT-NMD consortium and how it has provided a wider resource for any concerned parent, patient, or clinician to ask a question of ethical concern. Issues raised range from science related ethical issues, issues related to hereditary neuromuscular diseases and the new therapeutic approaches and questions concerning patients rights in the context of patient registries and bio-banks. We conclude by recommending the PEC as a model for similar research contexts in rare diseases.
doi:10.1371/currents.md.f90b49429fa814bd26c5b22b13d773ec
PMCID: PMC3544553  PMID: 23330068
5.  Muscle-fiber transdifferentiation in an experimental model of respiratory chain myopathy 
Arthritis Research & Therapy  2012;14(5):R233.
Introduction
Skeletal muscle fiber composition and muscle energetics are not static and change in muscle disease. This study was performed to determine whether a mitochondrial myopathy is associated with adjustments in skeletal muscle fiber-type composition.
Methods
Ten rats were treated with zidovudine, an antiretroviral nucleoside reverse transcriptase inhibitor that induces a myopathy by interfering with mitochondrial functions. Soleus muscles were examined after 21 weeks of treatment. Ten untreated rats served as controls.
Results
Zidovudine induced a myopathy with mitochondrial DNA depletion, abnormalities in mitochondrial ultrastructure, and reduced cytochrome c oxidase activity. Mitochondrial DNA was disproportionally more diminished in type I compared with type II fibers, whereas atrophy predominated in type II fibers. Compared with those of controls, zidovudine-exposed soleus muscles contained an increased proportion (256%) of type II fibers, whereas neonatal myosin heavy chains remained repressed, indicating fiber-type transformation in the absence of regeneration. Microarray gene-expression analysis confirmed enhanced fast-fiber isoforms, repressed slow-fiber transcripts, and reduced neonatal fiber transcripts in the mitochondrial myopathy. Respiratory chain transcripts were diminished, whereas the enzymes of glycolysis and glycogenolysis were enhanced, indicating a metabolic adjustment from oxidative to glycolytic capacities. A coordinated regulation was found of transcription factors known to orchestrate type II fiber formation (upregulation of MyoD, Six1, Six2, Eya1, and Sox6, and downregulation of myogenin and ERRγ).
Conclusions
The type I to type II fiber transformation in mitochondrial myopathy implicates mitochondrial function as a new regulator of skeletal muscle fiber type.
doi:10.1186/ar4076
PMCID: PMC3580545  PMID: 23107834
6.  Drug treatment of Duchenne muscular dystrophy: available evidence and perspectives 
Acta Myologica  2012;31(1):4-8.
Duchenne muscular dystrophy (DMD) is a disease linked to the X-chromosome which affects 1 in 3,600-6,000 newborn males. It is manifested by the absence of the dystrophin protein in muscle fibres, which causes progressive damage leading to death in the third decade of life. The only medication so far shown to be effective in delaying the progression of this illness are corticosteroids, which have been shown to increase muscle strength in randomised controlled studies; long-term studies have demonstrated that they prolong walking time and retard the progression of respiratory dysfunction, dilated cardiomyopathy and scoliosis. Several potential drugs are now being investigated. Genetic therapy, involving the insertion of a dystrophin gene through a vector, has proven effective in animals but not humans. Currently under clinical study is Ataluren, a molecule that binds with ribosomes and may allow the insertion of an aminoacid in the premature termination codon, and exon-skipping, which binds with RNA and excludes specific sites of RNA splicing, producing a dystrophin that is smaller but functional. There are also studies attempting to modulate other muscular proteins, such as myostatin and utrophin, to reduce symptoms. This paper does not address cardiomyopathy treatment in DMD patients.
PMCID: PMC3440798  PMID: 22655510
Duchenne muscular dystrophy; drug treatment; clinical trials
7.  ORAI1 deficiency and lack of store-operated Ca2+ entry cause immunodeficiency, myopathy and ectodermal dysplasia 
Background
Defects in the development or activation of T cells result in immunodeficiency associated with severe infections early in life. T cell activation requires Ca2+ influx through Ca2+-release activated Ca2+ (CRAC) channels encoded by the gene ORAI1.
Objective
Investigation of the genetic causes and the clinical phenotype of immunodeficiency in patients with impaired Ca2+ influx and CRAC channel function.
Methods
DNA sequence analysis for mutations in the genes ORAI1, ORAI2, ORAI3, stromal interaction molecules (STIM) 1 and 2 as well as mRNA and protein expression analysis of ORAI1 in immunodeficient patients. Immunohistochemical analysis of ORAI1 tissue distribution in healthy human donors.
Results
We identified mutations in ORAI1 in patients from two unrelated families. One patient is homozygous for a nonsense mutation in ORAI1 (ORAI1-A88SfsX25) and a second patient is compound heterozygous for two missense mutations in ORAI1 (ORAI1-A103E/L194P). All three mutations abolish ORAI1 expression and impair Ca2+ influx and CRAC channel function. The clinical syndrome associated with ORAI1 deficiency is characterized by immunodeficiency with a defect in the function but not the development of lymphocytes, congenital myopathy and anhydrotic ectodermal dysplasia (EDA) with a defect in dental enamel calcification. In contrast to the limited clinical phenotype, we found ORAI1 protein expression in a wide variety of cell types and organs.
Conclusion
Ca2+ influx through ORAI1 is crucial for lymphocyte function in vivo. Despite almost ubiquitous ORAI1 expression, the channel has a non-redundant role in only a few cell-types judging from the limited clinical phenotype in ORAI1 deficient patients.
doi:10.1016/j.jaci.2009.10.007
PMCID: PMC2829767  PMID: 20004786
ORAI1; STIM1; CRAC; calcium channel; Ca2+; store-operated Ca2+ entry; T cells; immunodeficiency; signal transduction; congenital myopathy; anhydrotic ectodermal dysplasia; dental enamel; amelogenesis imperfecta
8.  Proteomic identification of FHL1 as the protein mutated in human reducing body myopathy 
Reducing body myopathy (RBM) is a rare disorder causing progressive muscular weakness characterized by aggresome-like inclusions in the myofibrils. Identification of genes responsible for RBM by traditional genetic approaches has been impossible due to the frequently sporadic occurrence in affected patients and small family sizes. As an alternative approach to gene identification, we used laser microdissection of intracytoplasmic inclusions identified in patient muscle biopsies, followed by nanoflow liquid chromatography–tandem mass spectrometry and proteomic analysis. The most prominent component of the inclusions was the Xq26.3-encoded four and a half LIM domain 1 (FHL1) protein, expressed predominantly in skeletal but also in cardiac muscle. Mutational analysis identified 4 FHL1 mutations in 2 sporadic unrelated females and in 2 families with severely affected boys and less-affected mothers. Transfection of kidney COS-7 and skeletal muscle C2C12 cells with mutant FHL1 induced the formation of aggresome-like inclusions that incorporated both mutant and wild-type FHL1 and trapped other proteins in a dominant-negative manner. Thus, a novel laser microdissection/proteomics approach has helped identify both inherited and de novo mutations in FHL1, thereby defining a new X-linked protein aggregation disorder of muscle.
doi:10.1172/JCI34450
PMCID: PMC2242623  PMID: 18274675

Results 1-8 (8)