Centronuclear myopathy (CNM) is a genetically heterogeneous disorder associated with general skeletal muscle weakness, type I fiber predominance and atrophy, and abnormally centralized nuclei. Autosomal dominant CNM is due to mutations in the large GTPase dynamin 2 (DNM2), a mechanochemical enzyme regulating cytoskeleton and membrane trafficking in cells. To date, 40 families with CNM-related DNM2 mutations have been described, and here we report 60 additional families encompassing a broad genotypic and phenotypic spectrum. In total, 18 different mutations are reported in 100 families and our cohort harbors nine known and four new mutations, including the first splice-site mutation. Genotype–phenotype correlation hypotheses are drawn from the published and new data, and allow an efficient screening strategy for molecular diagnosis. In addition to CNM, dissimilar DNM2 mutations are associated with Charcot–Marie–Tooth (CMT) peripheral neuropathy (CMTD1B and CMT2M), suggesting a tissue-specific impact of the mutations. In this study, we discuss the possible clinical overlap of CNM and CMT, and the biological significance of the respective mutations based on the known functions of dynamin 2 and its protein structure. Defects in membrane trafficking due to DNM2 mutations potentially represent a common pathological mechanism in CNM and CMT.

Exercise intolerance due to impaired oxidative metabolism is a prominent symptom in patients with mitochondrial myopathy (MM), but it is still uncertain whether L-carnitine supplementation is beneficial for patients with MM. The aim of our study was to investigate the effects of L-carnitine on exercise performance in MM. Twelve MM subjects (mean age±SD=35.4±10.8 years) with chronic progressive external ophthalmoplegia (CPEO) were first compared to 10 healthy controls (mean age±SD=29±7.8 years) before they were randomly assigned to receive L-carnitine supplementation (3 g/daily) or placebo in a double-blind crossover design. Clinical status, body composition, respiratory function tests, peripheral muscle strength (isokinetic and isometric torque) and cardiopulmonary exercise tests (incremental to peak exercise and at 70% of maximal), constant work rate (CWR) exercise test, to the limit of tolerance [Tlim]) were assessed after 2 months of L-carnitine/placebo administration. Patients with MM presented with lower mean height, total body weight, fat-free mass, and peripheral muscle strength compared to controls in the pre-test evaluation. After L-carnitine supplementation, the patients with MM significantly improved their Tlim (14±1.9 vs 11±1.4 min) and oxygen consumption (V˙O2) at CWR exercise, both at isotime (1151±115 vs 1049±104 mL/min) and at Tlim (1223±114 vs 1060±108 mL/min). These results indicate that L-carnitine supplementation may improve aerobic capacity and exercise tolerance during high-intensity CWRs in MM patients with CPEO.

The model including TLL to predict the walked distance by healthy children explained more of the variation on the walked distance in the 6MWT than the model using the height but without significant difference between the models.

[Purpose] This systematic review evaluated the presence of sleep-disordered breathing in patients with myasthenia gravis and clarified the role of physiotherapy. [Subjects and Methods] We followed the PRISMA declaration criteria. The evaluation was performed in accordance with the STROBE statement for observational and cross-sectional studies and the CONSORT checklist for clinical trials. Searches were followed by hand on MEDLINE, EMBASE, SciELO, PubMed Central, and the Cochrane Central Register of Controlled Trials. [Results] Our searches yielded a total of 36 studies published between 1970 and 2014. The number of patients involved ranged from 9–490. Of the 36 studies, 19 articles were excluded because they did not meet the inclusion criteria. Therefore, 17 observational, cross-sectional, or clinical studies assessing the quality of sleep and prevalence of sleep disorders in patients with myasthenia gravis were eligible for our review. [Conclusion] Some studies of patients with MG show that patients with MG are associated with poor sleep quality, excessive daytime sleepiness, presence of restless syndrome, and a higher incidence of SDB, while other studies do not report such associations. Therefore, given the current inconclusive evidence and limited literature, further study of sleep disturbances in patients with MG is needed.