Phenotypic Spectrum of α-Dystroglycanopathies Associated With the c.919T>a Variant in the FKRP Gene in Humans and Mice

Mutations in the fukutin-related protein gene, FKRP, are the most frequent single cause of α-dystroglycanopathy. Rare FKRP mutations are clinically not well characterized. Here, we review the phenotype associated with the rare c.919T>A mutation in FKRP in humans and mice. We describe clinical and paraclinical findings in 6 patients, 2 homozygous, and 4-compound heterozygous for c.919T>A, and compare findings with a mouse model we generated, which is homozygous for the same mutation. In patients, the mutation at the homozygous state is associated with a severe congenital muscular dystrophy phenotype invariably characterized by severe multisystem disease and early death. Compound heterozygous patients have a severe limb-girdle muscular dystrophy phenotype, loss of ambulation before age 20 and respiratory insufficiency. In contrast, mice homozygous for the same mutation show no symptoms or signs of muscle disease. Evidence therefore defines the FKRP c.919T>A as a very severe mutation in humans. The huge discrepancy between phenotypes in humans and mice suggests that differences in protein folding/processing exist between human and mouse Fkrp. This emphasizes the need for more detailed structural analyses of FKRP and shows the challenges of developing appropriate animal models of dystroglycanopathies that mimic the disease course in humans

A behavioral analysis of investor diversification

This paper studies the link between individual investors’ portfolio diversification levels and various personal traits that proxy informational advantages and overconfidence. The analysis is based on objective data from the largest Turkish brokerage house tracking 59,951 individual investors’ accounts with a total of 3,248,654 million transactions over the period 2008–2010. Wealthier, highly educated, older investors working in the finance sector and those trading relatively often show higher diversification levels possibly because they are better equipped to obtain and process information. Finance professionals, married investors, and those placing high-volume orders through investment centers show poorer diversification possibly as a reflection of overconfidence. Our analysis reveals important nonlinear effects, implying that the marginal impact of overconfidence on diversification is not uniform across investors but varies according to the investor's information gathering and processing abilities

Results of an open label feasibility study of sodium valproate in people with McArdle disease

McArdle disease results from a lack of muscle glycogen phosphorylase in skeletal muscle tissue. Regenerating skeletal muscle fibres can express the brain glycogen phosphorylase isoenzyme. Stimulating expression of this enzyme could be a therapeutic strategy. Animal model studies indicate that sodium valproate (VPA) can increase expression of phosphorylase in skeletal muscle affected with McArdle disease. This study was designed to assess whether VPA can modify expression of brain phosphorylase isoenzyme in people with McArdle disease. This phase II, open label, feasibility pilot study to assess efficacy of six months treatment with VPA (20 mg/kg/day) included 16 people with McArdle disease. Primary outcome assessed changes in VO2peak during an incremental cycle test. Secondary outcomes included: phosphorylase enzyme expression in post-treatment muscle biopsy, total distance walked in 12 min, plasma lactate change (forearm exercise test) and quality of life (SF36). Safety parameters. 14 participants completed the trial, VPA treatment was well tolerated; weight gain was the most frequently reported drug-related adverse event. There was no clinically meaningful change in any of the primary or secondary outcome measures including: VO2peak, 12 min walk test and muscle biopsy to look for a change in the number of phosphorylase positive fibres between baseline and 6 months of treatment. Although this was a small open label feasibility study, it suggests that a larger randomised controlled study of VPA, may not be worthwhile

A comparative study of the factors shaping postsecondary aspirations for low-income students in greater Boston and greater London

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordThis project investigated the postsecondary education aspirations of 27 secondary schoolaged students living in greater London, England and greater Boston, Massachusetts, USA. An innovative research design was implemented to support a technology-facilitated international focus group allowing for exchanges between the U.S. and English students. Using human ecology theory, the findings show that differences in students’ exosystems, specifically the financial aid and loan repayment processes, influence student postsecondary education and career aspirations. U.S. student concerns about affordability and loan repayment made aspirations lower and more localized. In contrast, English participants felt comforted by their government’s deferred loan repayment process, so they did not express as strong constraints on aspirations based on financial considerations. Both English and U.S. students were influenced similarly by the mesosystem when making decisions about which postsecondary institution to attend. In conclusion, altering exosystem policy and influencing mesosystem relationships could impact postsecondary education aspirations for low-income students

From exercise intolerance to functional improvement: The second wind phenomenon in the identification of McArdle disease

McArdle disease is the most common of the glycogen storage diseases. Onset of symptoms is usually in childhood with muscle pain and restricted exercise capacity. Signs and symptoms are often ignored in children or put down to 'growing pains' and thus diagnosis is often delayed. Misdiagnosis is not uncommon because several other conditions such as muscular dystrophy and muscle channelopathies can manifest with similar symptoms. A simple exercise test performed in the clinic can however help to identify patients by revealing the second wind phenomenon which is pathognomonic of the condition. Here a patient is reported illustrating the value of using a simple 12 minute walk test.RSS is funded by Ciências sem Fronteiras/CAPES Foundation. The authors would like to thank the Association for Glycogen Storage Disease (UK), the EUROMAC Registry funded by the European Union, the Muscular Dystrophy Campaign, the NHS National Specialist Commissioning Group and the Myositis Support Group for funding

Low survival rate and muscle fiber-dependent aging effects in the McArdle disease mouse model

Altres ajuts: The present study was funded by grants received from the Fondo de Investigaciones Sanitarias (FIS, grant PI16/01492 and PI15/00558) and cofunded by 'Fondos FEDER'. Gisela Nogales-Gadea is supported by a Trampoline Grant #21108 from AMF Telethon.McArdle disease is an autosomal recessive disorder caused by the absence of the muscle glycogen phosphorylase, which leads to impairment of glycogen breakdown. The McArdle mouse, a model heavily affected by glycogen accumulation and exercise intolerance, was used to characterize disease progression at three different ages. The molecular and histopathological consequences of the disease were analyzed in five different hind-limb muscles (soleus, extensor digitorum longus, tibialis anterior, gastrocnemius and quadriceps) of young (8-week-old), adult (35-week-old) and old (70-week-old) mice. We found that McArdle mice have a high perinatal and post-weaning mortality. We also observed a progressive muscle degeneration, fibrosis and inflammation process that was not associated with an increase in muscle glycogen content during aging. Additionally, this progressive degeneration varied among muscle and fiber types. Finally, the lack of glycogen content increase was associated with the inactivation of glycogen synthase and not with compensatory expression of the Pygl and/or Pygb genes in mature muscle

Efficacy and safety of rozanolixizumab in moderate to severe generalized myasthenia gravis : a phase 2 randomized control trial

OBJECTIVE: To explore the clinical efficacy and safety of subcutaneous (SC) rozanolixizumab, an anti-neonatal Fc receptor humanized monoclonal antibody, in patients with generalized myasthenia gravis (gMG). METHODS: In this phase 2a, randomized, double-blind, placebo-controlled, 2-period, multicenter trial (NCT03052751), patients were randomized (1:1) in period 1 (days 1-29) to 3 once-weekly (Q1W) SC infusions of rozanolixizumab 7 mg/kg or placebo. In period 2 (days 29-43), patients were re-randomized to either rozanolixizumab 7 mg/kg or 4 mg/kg (3 Q1W SC infusions), followed by an observation period (days 44-99). Primary endpoint was change from baseline to day 29 in Quantitative Myasthenia Gravis (QMG) score. Secondary endpoints were change from baseline to day 29 in MG-Activities of Daily Living (MG-ADL) and MG-Composite (MGC) scores and safety. RESULTS: Forty-three patients were randomized (rozanolixizumab 21, placebo 22 [period 1]). Least squares (LS) mean change from baseline to day 29 for rozanolixizumab vs placebo was as follows: QMG (LS mean -1.8 vs -1.2, difference -0.7, 95% upper confidence limit [UCL] 0.8; p = 0.221; not statistically significant), MG-ADL (LS mean -1.8 vs -0.4, difference -1.4, 95% UCL -0.4), and MGC (LS mean -3.1 vs -1.2, difference -1.8, 95% UCL 0.4) scores. Efficacy measures continued to improve with rozanolixizumab 7 mg/kg in period 2. The most common adverse event in period 1 was headache (rozanolixizumab 57%, placebo 14%). CONCLUSION: Whereas change from baseline in QMG was not statistically significant, the data overall suggest rozanolixizumab may provide clinical benefit in patients with gMG and was generally well tolerated. Phase 3 evaluation is ongoing (NCT03971422). CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that for patients with gMG, rozanolixizumab is well-tolerated, but did not significantly improve QMG score

Low aerobic capacity in McArdle disease : A role for mitochondrial network impairment?

McArdle disease is caused by myophosphorylase deficiency and results in complete inability for muscle glycogen breakdown. A hallmark of this condition is muscle oxidation impairment (e.g., low peak oxygen uptake (VO)), a phenomenon traditionally attributed to reduced glycolytic flux and Krebs cycle anaplerosis. Here we hypothesized an additional role for muscle mitochondrial network alterations associated with massive intracellular glycogen accumulation. We analyzed in depth mitochondrial characteristics-content, biogenesis, ultrastructure-and network integrity in skeletal-muscle from McArdle/control mice and two patients. We also determined VO in patients (both sexes, N = 145) and healthy controls (N = 133). Besides corroborating very poor VO values in patients and impairment in muscle glycolytic flux, we found that, in McArdle muscle: (a) damaged fibers are likely those with a higher mitochondrial and glycogen content, which show major disruption of the three main cytoskeleton components-actin microfilaments, microtubules and intermediate filaments-thereby contributing to mitochondrial network disruption in skeletal muscle fibers; (b) there was an altered subcellular localization of mitochondrial fission/fusion proteins and of the sarcoplasmic reticulum protein calsequestrin-with subsequent alteration in mitochondrial dynamics/function; impairment in mitochondrial content/biogenesis; and (c) several OXPHOS-related complex proteins/activities were also affected. In McArdle disease, severe muscle oxidative capacity impairment could also be explained by a disruption of the mitochondrial network, at least in those fibers with a higher capacity for glycogen accumulation. Our findings might pave the way for future research addressing the potential involvement of mitochondrial network alterations in the pathophysiology of other glycogenoses

Ocular, bulbar, limb, and cardiopulmonary involvement in oculopharyngeal muscular dystrophy

OBJECTIVES: To assess skeletal muscle weakness and progression as well as the cardiopulmonary involvement in oculopharyngeal muscular dystrophy (OPMD). MATERIALS AND METHODS: Cross-sectional study including symptomatic patients with genetically confirmed OPMD. Patients were assessed by medical history, ptosis, ophthalmoplegia, facial and limb strength, and swallowing capability. Cardiopulmonary function was evaluated using forced expiratory capacity in 1 s (FEV1), electrocardiogram (ECG), Holter monitoring, and echocardiography. RESULTS: We included 13 symptomatic patients (six males, mean age; 64 years (41-80) from 8 families. Ptosis was the first symptom in 8/13 patients followed by limb weakness in the remaining 5 patients Dysphagia was never the presenting symptom. At the time of examination, all affected patients had ptosis or had previously been operated for ptosis, while ophthalmoplegia was found in 9 patients. Dysphagia, tested by cold-water swallowing test, was abnormal in 9 patients (17-116 s, ref <8 s). Six patients could not climb stairs of whom two were wheelchair bound and one used a rollator. Six patients had reduced FEV1 (range 23%-59%). No cardiac involvement was identified. CONCLUSIONS: Limiting limb weakness is common in OPMD and can even be the presenting symptom of the disease. In contrast, dysphagia was not the initial symptom in any of our patients, although it was obligatory for diagnosing OPMD before genetic testing became available. Mild respiratory dysfunction, but no cardiac involvement, was detected

Impairments in contractility and cytoskeletal organisation cause nuclear defects in nemaline myopathy

Nemaline myopathy (NM) is a skeletal muscle disorder caused by mutations in genes that are generally involved in muscle contraction, in particular those related to the structure and/or regulation of the thin filament. Many pathogenic aspects of this disease remain largely unclear. Here, we report novel pathological defects in skeletal muscle fibres of mouse models and patients with NM: irregular spacing and morphology of nuclei; disrupted nuclear envelope; altered chromatin arrangement; and disorganisation of the cortical cytoskeleton. Impairments in contractility are the primary cause of these nuclear defects. We also establish the role of microtubule organisation in determining nuclear morphology, a phenomenon which is likely to contribute to nuclear alterations in this disease. Our results overlap with findings in diseases caused directly by mutations in nuclear envelope or cytoskeletal proteins. Given the important role of nuclear shape and envelope in regulating gene expression, and the cytoskeleton in maintaining muscle fibre integrity, our findings are likely to explain some of the hallmarks of NM, including contractile filament disarray, altered mechanical properties and broad transcriptional alterations