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Desaphy J.-F.,University of Bari | Carbonara R.,University of Bari | D'Amico A.,Unit of Neuromuscular and Neurodegenerative Disorders | Modoni A.,Catholic University of the Sacred Heart | And 6 more authors.
Neurology | Year: 2016

Objective: We performed a clinical, functional, and pharmacologic characterization of the novel p.P1158L Nav1.4 mutation identified in a young girl presenting a severe myotonic phenotype. Methods: Wild-type hNav1.4 channel and P1158L mutant were expressed in tsA201 cells for functional and pharmacologic studies using patch-clamp. Results: The patient shows pronounced myotonia, slowness of movements, and generalized muscle hypertrophy. Because of general discomfort with mexiletine, she was given flecainide with satisfactory response. In vitro, mutant channels show a slower current decay and a rightward shift of the voltage dependence of fast inactivation. The voltage dependence of activation and slow inactivation were not altered. Mutant channels were less sensitive to mexiletine, whereas sensitivity to flecainide was not altered. The reduced inhibition of mutant channels by mexiletine was also observed using clinically relevant drug concentrations in a myotonic-like condition. Conclusions: Clinical phenotype and functional alterations of P1158L support the diagnosis of myotonia permanens. Impairment of fast inactivation is consistent with the possible role of the channel domain III S4-S5 loop in the inactivation gate docking site. The reduced sensitivity of P1158L to mexiletine may have contributed to the unsatisfactory response of the patient. The success of flecainide therapy underscores the usefulness of in vitro functional studies to help in the choice of the best drug for each individual. © 2016 American Academy of Neurology. Source

Lo Monaco M.,Catholic University of the Sacred Heart | D'Amico A.,Unit of Neuromuscular and Neurodegenerative Disorders | Luigetti M.,Catholic University of the Sacred Heart | Desaphy J.-F.,University of Bari | Modoni A.,Catholic University of the Sacred Heart
Clinical Neurophysiology | Year: 2015

Objective: We aim to demonstrate the effect of mexiletine on the compound muscle action potential (CMAP) amplitude transitory depression (TD) in a cohort of patients with recessive myotonia congenita. Methods: We evaluated 21 patients with recessive myotonia congenita referred to our institute from 1990 to 2013 and treated with mexiletine chlorhydrate. All patients underwent prolonged 3. Hz repetitive nerve stimulation (3. Hz-PLRS) before and after the beginning of treatment. Results: We observed in all subjects a reduction of CMAP amplitude TD after the beginning of treatment. The mean value of the TD nadir before starting mexiletine treatment was -62.0% and reduced to -28.8% after the therapy was started (51.6% reduction, p< 0.001). Conclusions: The 3. Hz-PLRS is configured as a neurophysiological test able to indirectly detect and quantify, through the measurement of TD, the clinical phenomenon of the transitory weakness that occurs in myotonic syndromes due to CLCN1 mutations. Significance: This neurophysiological test might be considered a helpful tool to assess the effect of anti-myotonic drugs, as mexiletine, in recessive myotonia congenita. © 2014 International Federation of Clinical Neurophysiology. Source

Ayoglu B.,KTH Royal Institute of Technology | Chaouch A.,Northumbria University | Lochmuller H.,Northumbria University | Politano L.,The Second University of Naples | And 20 more authors.
EMBO Molecular Medicine | Year: 2014

Despite the recent progress in the broad-scaled analysis of proteins in body fluids, there is still a lack in protein profiling approaches for biomarkers of rare diseases. Scarcity of samples is the main obstacle hindering attempts to apply discovery driven protein profiling in rare diseases. We addressed this challenge by combining samples collected within the BIO-NMD consortium from four geographically dispersed clinical sites to identify protein markers associated with muscular dystrophy using an antibody bead array platform with 384 antibodies. Based on concordance in statistical significance and confirmatory results obtained from analysis of both serum and plasma, we identified eleven proteins associated with muscular dystrophy, among which four proteins were elevated in blood from muscular dystrophy patients: carbonic anhydrase III (CA3) and myosin light chain 3 (MYL3), both specifically expressed in slow-twitch muscle fibers and mitochondrial malate dehydrogenase 2 (MDH2) and electron transfer flavoprotein A (ETFA). Using age-matched sub-cohorts, 9 protein profiles correlating with disease progression and severity were identified, which hold promise for the development of new clinical tools for management of dystrophinopathies. © 2014 The Authors. Source

Maggi L.,Neuromuscular Diseases and Neuroimmunology | D'Amico A.,Unit of Neuromuscular and Neurodegenerative Disorders | Pini A.,IRCCS Institute of Neurological science | Sivo S.,Catholic University | And 28 more authors.
Neurology | Year: 2014

Objectives: Our aim was to conduct a comparative study in a large cohort of myopathic patients carrying LMNA gene mutations to evaluate clinical and molecular features associated with different phenotypes. Methods: We performed a retrospective cohort study of 78 myopathic patients with LMNA mutation and 30 familial cases with LMNA mutation without muscle involvement. We analyzed features characterizing the various forms of LMNA-related myopathy through correlation statistics. Results: Of the 78 patients, 37 (47%) had limb-girdle muscular dystrophy 1B (LGMD1B), 18 (23%) congenital muscular dystrophy (MDCL), 17 (22%) autosomal dominant Emery-Dreifuss muscular dystrophy 2 (EDMD2), and 6 (8%) an atypical myopathy. The myopathic phenotypes shared a similar cardiac impairment. Cardioverter defibrillator or pacemaker was implanted in 41 (53%) myopathic patients compared to 7 (23%) familial cases without muscle involvement (p = 0.005). Heart transplantation was performed in 8 (10.3%) myopathic patients and in none of the familial cases. Ten (12.8%) myopathic patients died; there were no deaths among the familial cases (p = 0.032). Missense mutations were found in 14 patients (82%) with EDMD2 and 14 patients (78%) with MDCL compared to 17 patients (45%) with LGMD1B and 4 (67%) atypical patients. Frameshift mutations were detected in 17 (45%) LGMD1B compared to 3 (18%) EDMD2, 1 (6%) MDCL, and 2 (33%) with atypical myopathy (p = 0.021). Furthermore, frameshift mutations were found in 30 of 73 patients (41%) with heart involvement compared to 4 of 35 (11%) without heart involvement (p = 0.004). Conclusions: Our data provided new insights in LMNA-related myopathies, whose natural history appears to be dominated by cardiac involvement and related complications. © 2014 American Academy of Neurology. Source

Peverelli L.,Neuromuscular and Rare Diseases Unit | Testolin S.,Neuromuscular and Rare Diseases Unit | Villa L.,Neuromuscular and Rare Diseases Unit | D'Amico A.,Laboratory of Molecular Medicine for Muscular and Neurodegenerative Diseases | And 9 more authors.
Neurology | Year: 2015

Objective: Duchenne muscular dystrophy (DMD) is a lethal disease. The outcome measures used in numerous therapeutic trials include skeletal muscle biopsy. We studied the natural history of DMD from the standpoint of muscle histology with the aim of providing a reproducible tool for use in evaluating and comparing any histologic changes occurring in patients with DMD undergoing treatment and hence be able to determine how therapy modulates the histologic evolution of the disease. Methods: Three independent operators analyzed 56 muscle biopsies from 40 patients not treated with steroids, aged 1 to 10 years and 16 individuals treated with steroids, aged 7 to 10 years. We analyzed morphologic measures, normalized every measure for the average number of fibers observed for each year of age, and calculated intraclass correlation coefficients. Results: The average proportion of connective tissue in patients not treated with steroids was 16.98% from ages 1 to 6 years and 30% from ages 7 to 10 years (p < 0.0001). The average proportion in patients treated with steroids was 24.90%. Muscle fiber area mirrored that of connective tissue in both groups. Conclusions: Having provided a reproducible tool for evaluation and comparison of histologic changes occurring in patients undergoing clinical trials, it was observed that at ages 6 to 7 years, fibrotic tissue rapidly peaks to 29.85%; this is a crucial moment when muscle tissue loses its self-regeneration ability, veering toward fibrotic degeneration. These data should be considered when deciding the most suitable time to begin therapy. © 2015 American Academy of Neurology. Source

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