Reduced serum myostatin concentrations associated with genetic muscle disease progression.

Myostatin is a highly conserved protein secreted primarily from skeletal muscle that can potently suppress muscle growth. This ability to regulate skeletal muscle mass has sparked intense interest in the development of anti-myostatin therapies for a wide array of muscle disorders including sarcopenia, cachexia and genetic neuromuscular diseases. While a number of studies have examined the circulating myostatin concentrations in healthy and sarcopenic populations, very little data are available from inherited muscle disease patients.

Structural analysis of pathogenic mutations in the DYRK1A gene in patients with developmental disorders.

Haploinsufficiency in DYRK1A is associated with a recognizable developmental syndrome, though the mechanism of action of pathogenic missense mutations is currently unclear. Here we present 19 de novo mutations in this gene, including five missense mutations, identified by the Deciphering Developmental Disorder study. Protein structural analysis reveals that the missense mutations are either close to the ATP or peptide binding-sites within the kinase domain, or are important for protein stability, suggesting they lead to a loss of the protein's function mechanism.

Clinical and neuroimaging findings in two brothers with limb girdle muscular dystrophy due to LAMA2 mutations.

Recessive mutations in LAMA2 commonly cause congenital muscular dystrophy (MDC1A) and, rarely, limb girdle muscular dystrophy (LGMD). We report 2 brothers who presented in adulthood with LGMD due to novel mutations in LAMA2 identified by whole exome sequencing (WES). Muscle biopsy more than 30 years ago demonstrated dystrophic changes but was not available for immunoanalysis.

The Human Phenotype Ontology in 2017.

Deep phenotyping has been defined as the precise and comprehensive analysis of phenotypic abnormalities in which the individual components of the phenotype are observed and described. The three components of the Human Phenotype Ontology (HPO; www.human-phenotype-ontology.

Recessive mutations in the kinase ZAK cause a congenital myopathy with fibre type disproportion.

Congenital myopathies define a heterogeneous group of neuromuscular diseases with neonatal or childhood hypotonia and muscle weakness. The genetic cause is still unknown in many patients, precluding genetic counselling and better understanding of the physiopathology. To identify novel genetic causes of congenital myopathies, exome sequencing was performed in three consanguineous families.

Economic Evaluation in Duchenne Muscular Dystrophy: Model Frameworks for Cost-Effectiveness Analysis.

Background: Several treatments are on the horizon for Duchenne muscular dystrophy (DMD), a terminal orphan disease. In many jurisdictions, decisions regarding pricing and reimbursement of these health technologies comprise evidence of value for money.

Objective: The objective of this study was to develop a cost-effectiveness model based on the Duchenne muscular dystrophy Functional Ability Self-Assessment Tool (DMDSAT), a new rating scale created specifically to measure disease progression in clinical practice and trials and model DMD in economic evaluations, and compare it with two alternative model structures.

Association Study of Exon Variants in the NF-κB and TGFβ Pathways Identifies CD40 as a Modifier of Duchenne Muscular Dystrophy.

The expressivity of Mendelian diseases can be influenced by factors independent from the pathogenic mutation: in Duchenne muscular dystrophy (DMD), for instance, age at loss of ambulation (LoA) varies between individuals whose DMD mutations all abolish dystrophin expression. This suggests the existence of trans-acting variants in modifier genes. Common single nucleotide polymorphisms (SNPs) in candidate genes (SPP1, encoding osteopontin, and LTBP4, encoding latent transforming growth factor β [TGFβ]-binding protein 4) have been established as DMD modifiers.

The Clinical Outcome Study for dysferlinopathy: An international multicenter study.

Objective: To describe the baseline clinical and functional characteristics of an international cohort of 193 patients with dysferlinopathy.

Methods: The Clinical Outcome Study for dysferlinopathy (COS) is an international multicenter study of this disease, evaluating patients with genetically confirmed dysferlinopathy over 3 years. We present a cross-sectional analysis of 193 patients derived from their baseline clinical and functional assessments.

Why are some patients with Duchenne muscular dystrophy dying young: An analysis of causes of death in North East England.

Introduction: Duchenne muscular dystrophy (DMD) is the most common inherited muscle disease in children. Recent years have seen an increase in age of survival into adulthood following the introduction of proactive standards of care. We reviewed mortality in DMD in our population in order to identify potential underlying risk factors for premature death and improve clinical care.

Cardiac involvement in hereditary myopathy with early respiratory failure: A cohort study.

Objective: To assess whether hereditary myopathy with early respiratory failure (HMERF) due to the c.951434T>C; (p.Cys31712Arg) TTN missense mutation also includes a cardiac phenotype.

Prospective exploratory muscle biopsy, imaging, and functional assessment in patients with late-onset Pompe disease treated with alglucosidase alfa: The EMBASSY Study.

Background: Late-onset Pompe disease is characterized by progressive skeletal myopathy followed by respiratory muscle weakness, typically leading to loss of ambulation and respiratory failure. In this population, enzyme replacement therapy (ERT) with alglucosidase alfa has been shown to stabilize respiratory function and improve mobility and muscle strength. Muscle pathology and glycogen clearance from skeletal muscle in treatment-naïve adults after ERT have not been extensively examined.

Muscle hypertrophy as the presenting sign in a patient with a complete FHL1 deletion.

Four and a half LIM protein 1 (FHL1/SLIM1) has recently been identified as the causative gene mutated in four distinct diseases affecting skeletal muscle that have overlapping features, including reducing body myopathy, X-linked myopathy, X-linked dominant scapuloperoneal myopathy and Emery-Dreifuss muscular dystrophy. FHL1 localises to the sarcomere and the sarcolemma and is believed to participate in muscle growth and differentiation as well as in sarcomere assembly. We describe in this case report a boy with a deletion of the entire FHL1 gene who is now 15 years of age and presented with muscle hypertrophy, reduced subcutaneous fat, rigid spine and short stature.

Stakeholder cooperation to overcome challenges in orphan medicine development: the example of Duchenne muscular dystrophy.

Duchenne muscular dystrophy is a rare, progressive, muscle-wasting disease leading to severe disability and premature death. Treatment is currently symptomatic, but several experimental therapies are in development. Implemented care standards, validated outcome measures correlating with clinical benefit, and comprehensive information about the natural history of the disease are essential for regulatory approval of any treatment.

A heterozygous 21-bp deletion in CAPN3 causes dominantly inherited limb girdle muscular dystrophy.

Limb girdle muscular dystrophy type 2A is the most common limb girdle muscular dystrophy form worldwide. Although strict recessive inheritance is assumed, patients carrying a single mutation in the calpain 3 gene (CAPN3) are reported. Such findings are commonly attributed to incomplete mutation screening.

Prevalence of Pompe disease in 3,076 patients with hyperCKemia and limb-girdle muscular weakness.

Objective: We prospectively screened a large European cohort of patients presenting with hyperCKemia and/or limb-girdle muscular weakness (LGMW) for acid α-glucosidase (GAA) deficiency by dried blood spot (DBS) investigation.

Methods: DBS were collected from 3,076 consecutive adult patients from 7 German and British neuromuscular centers. All specimens were investigated for GAA deficiency by fluorometry.

Limb-girdle muscular dystrophies - international collaborations for translational research.

The limb-girdle muscular dystrophies (LGMDs) are a diverse group of genetic neuromuscular conditions that usually manifest in the proximal muscles of the hip and shoulder girdles. Since the identification of the first gene associated with the phenotype in 1994, an extensive body of research has identified the genetic defects responsible for over 30 LGMD subtypes, revealed an increasingly varied phenotypic spectrum, and exposed the need to move towards a systems-based understanding of the molecular pathways affected. New sequencing technologies, including whole-exome and whole-genome sequencing, are continuing to expand the range of genes and phenotypes associated with the LGMDs, and new computational approaches are helping clinicians to adapt to this new genomic medicine paradigm.

Quantifying the burden of caregiving in Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a rare pediatric neuromuscular disease associated with progressive muscle degeneration and extensive care needs. Our objective was to estimate the caregiver burden associated with DMD. We made cross-sectional assessments of caregiver health-related quality of life (HRQL) and burden using the EuroQol EQ-5D, a Visual Analogue Scale (VAS), the SF-12 Health Survey, and the Zarit Caregiver Burden Interview (ZBI) administered online.

Deep RNA profiling identified CLOCK and molecular clock genes as pathophysiological signatures in collagen VI myopathy.

Collagen VI myopathies are genetic disorders caused by mutations in collagen 6 A1, A2 and A3 genes, ranging from the severe Ullrich congenital muscular dystrophy to the milder Bethlem myopathy, which is recapitulated by collagen-VI-null (Col6a1(-/-)) mice. Abnormalities in mitochondria and autophagic pathway have been proposed as pathogenic causes of collagen VI myopathies, but the link between collagen VI defects and these metabolic circuits remains unknown. To unravel the expression profiling perturbation in muscles with collagen VI myopathies, we performed a deep RNA profiling in both Col6a1(-/-)mice and patients with collagen VI pathology.

Muscle-Derived Proteins as Serum Biomarkers for Monitoring Disease Progression in Three Forms of Muscular Dystrophy.

Background: Identifying translatable, non-invasive biomarkers of muscular dystrophy that better reflect the disease pathology than those currently available would aid the development of new therapies, the monitoring of disease progression and the response to therapy.

Objective: The goal of this study was to evaluate a panel of serum protein biomarkers with the potential to specifically detect skeletal muscle injury.

Method: Serum concentrations of skeletal troponin I (sTnI), myosin light chain 3 (Myl3), fatty acid binding protein 3 (FABP3) and muscle-type creatine kinase (CKM) proteins were measured in 74 Duchenne muscular dystrophy (DMD), 38 Becker muscular dystrophy (BMD) and 49 Limb-girdle muscular dystrophy type 2B (LGMD2B) patients and 32 healthy controls.

Compliance to Care Guidelines for Duchenne Muscular Dystrophy.

Background: International care guidelines for Duchenne muscular dystrophy (DMD) were published in 2010, but compliance in clinical practice is unknown.

Objective: The objective of our study was to compare real-world DMD care in Germany, Italy, the UK, and the US with the clinical recommendations.

Methods: DMD patients from Germany, Italy, the UK, and the US were identified through Translational Research in Europe - Assessment & Treatment of Neuromuscular Diseases (TREAT-NMD) registries and invited with a caregiver to complete a questionnaire with questions regarding DMD-related healthcare.

Improving the informed consent process in international collaborative rare disease research: effective consent for effective research.

The increased international sharing of data in research consortia and the introduction of new technologies for sequencing challenge the informed consent (IC) process, adding complexities that require coordination between research centres worldwide. Rare disease consortia present special challenges since available data and samples may be very limited. Thus, it is especially relevant to ensure the best use of available resources but at the same time protect patients' right to integrity.

Where do we stand in trial readiness for autosomal recessive limb girdle muscular dystrophies?

Autosomal recessive limb girdle muscular dystrophies (LGMD2) are a group of genetically heterogeneous diseases that are typically characterised by progressive weakness and wasting of the shoulder and pelvic girdle muscles. Many of the more than 20 different conditions show overlapping clinical features with other forms of muscular dystrophy, congenital, myofibrillar or even distal myopathies and also with acquired muscle diseases. Although individually extremely rare, all types of LGMD2 together form an important differential diagnostic group among neuromuscular diseases.

Elusive sources of variability of dystrophin rescue by exon skipping.

Background: Systemic delivery of anti-sense oligonucleotides to Duchenne muscular dystrophy (DMD) patients to induce de novo dystrophin protein expression in muscle (exon skipping) is a promising therapy. Treatment with Phosphorodiamidate morpholino oligomers (PMO) lead to shorter de novo dystrophin protein in both animal models and DMD boys who otherwise lack dystrophin; however, restoration of dystrophin has been observed to be highly variable. Understanding the factors causing highly variable induction of dystrophin expression in pre-clinical models would likely lead to more effective means of exon skipping in both pre-clinical studies and human clinical trials.

Prophylactic oral bisphosphonate therapy in duchenne muscular dystrophy.

Introduction: We assessed prophylactic use of bisphosphonate (BP) in Duchenne muscular dystrophy (DMD) patients on glucocorticoid (GC) therapy.

Methods: Fifty-two DMD patients on daily GC were offered BP (oral risedronate). Patients were reviewed for tolerability, side effects, bone pain, and fracture frequency.