Limb girdle muscular dystrophy type 2 (LGMD2) is a genetically heterogeneous autosomal recessive disorder caused by mutations in 15 known genes. DNA sequencing of all candidate genes can be expensive and laborious, whereas a selective sequencing approach often fails to provide a molecular diagnosis. We aimed to efficiently identify pathogenic mutations via homozygosity mapping in a population in which the genetics of LGMD2 has not been well characterized. Thirteen consanguineous families containing a proband with LGMD2 were recruited from Saudi Arabia, and for 11 of these families, selected individuals were genotyped at 10,204 single nucleotide polymorphisms. Linkage analysis excluded all but one or two known genes in ten of 11 genotyped families, and haplotype comparisons between families allowed further reduction in the number of candidate genes that were screened. Mutations were identified by DNA sequencing in all 13 families, including five novel mutations in four genes, by sequencing at most two genes per family. One family was reclassified as having a different myopathy based on genetic and clinical data after linkage analysis excluded all known LGMD2 genes. LGMD2 subtypes A and B were notably absent from our sample of patients, indicating that the distribution of LGMD2 mutations in Saudi Arabian families may be different than in other populations. Our data demonstrate that homozygosity mapping in consanguineous pedigrees offers a more efficient means of discovering mutations that cause heterogeneous disorders than comprehensive sequencing of known candidate genes.

Duchenne muscular dystrophy (DMD) is an X-linked form of muscular dystrophy characterized by progressive limb-girdle distribution of muscle weakness. Morbidity related to cardiomyopathy (CMO) is common, but cerebral infarction (CI) is relatively rare in these patients. We report a case of a pontine infarct in a patient with DMD and advanced CMO, and review the published data on CMO and CI in patients with DMD. Copyright © 2010 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Exon-skipping oligonucleotides are a well-researched therapeutic strategy for Duchenne’s muscular dystrophy (DMD). Despite remarkable successes in animal models with intramuscular and intravenous delivery of unmodified oligonucleotides, the ability to specifically target both normal and dystrophic muscle with a simple peptide ligand could decrease the therapeutic dose required and reduce the potential for toxicity. Thus, 3 rounds of in vivo phage display utilizing a 12-mer peptide library were performed with mdx mice and a peptide motif with potential for targeting to muscle but not liver was identified. This motif was shown to have enhanced binding affinity to C2C12 myoblasts over a scrambled control peptide and in vivo application of a fluorescein-labeled peptide containing the identified motif resulted in increased specificity for the heart and quadriceps muscle after tail-vein administration in C57BL/6 mice. This work has many potential applications for oligonucleotide or drug delivery to muscle for myopathies. Copyright © 2010. Published by Elsevier Inc.

This study was aimed to identify Fukutin (FKTN)-related congenital muscular dystrophies (CMD) with defective alpha-dystroglycan glycosylation in Korea and to discuss their genotype-phenotype spectrum focusing on detailed brain magnetic resonance imaging (MRI) findings. FKTN mutations were found in nine of the 12 CMD patients with defective alpha-dystroglycan glycosylation patients (75%). Two patients were homozygous for the Japanese founder retrotransposal insertion mutation. Seven patients were heterozygous for the retrotransposal insertion mutation, five of whom carried a novel intronic mutation that activates a pseudoexon between exons 5 and 6 (c.647+2084G>T). Compared with individuals that were homozygous for the retrotransposal insertion mutation, the seven heterozygotes for the retrotransposal insertion mutation, including five patients with the novel pseudoexon mutation, exhibited a more severe clinical phenotype in terms of motor abilities and more extensive brain MRI abnormalities (i.e., a wider distribution of cortical malformation and pons and cerebellar hypoplasia). FKTN mutations are the most common genetic cause of CMD with defective alpha-dystroglycan glycosylation in Korea. Compound heterozygosity of the retrotransposal insertion and the novel pseudoexon mutation is the most prevalent genotype in Korea and is associated with a more severe clinical and radiological phenotype compared with homozygosity for the retrotransposal insertion mutation. Copyright © 2010. Published by Elsevier B.V.

ABSTRACT: BACKGROUND: The administration of rituximab (RTX) in vivo results in B-cell depletion, but evidence for multiple mechanisms of action have been reported. Surprisingly, B cell depletion produced a response in patients with polymyositis, which is characterized as a T cell-mediated autoimmune disorder with biopsy findings similar to Miyoshi myopathy (MM). Indeed, in dysferlinopathies, there is evidence of immune system involvement including the presence of muscle inflammation and a down regulation of the complement inhibitory factor, CD55. METHODS: Two patients were treated with four weekly infusions of RTX 375 mg/m2. To measure the improvement in muscle strength after treatment, the isometric hand grip maximal voluntary contraction (MVC) was measured by load cell four times during treatment, and again after one year. In order to assess the reproducibility of our grip assessment, we determined the hand MVC analysis in 16 healthy subjects. Moreover, we measured the number of B cells present in patients by flow cytometric analysis during the course of treatment. RESULTS: The analysis of B cell number during the course of treatment showed that CD20- and CD19-positive cells were depleted to 0-0.01%. The decrease in B cells was followed by an improvement in the mobility of the pelvic and shoulder girdles as shown by the MRC%. The MVC values of both patients began at values lower than normal whereas during treatment patients had improved percentage of muscle strength. The strength peak in both patients coincided with the minimum B cell values. There were no severe adverse events associated with an infusion of RTX. CONCLUSION: We consider the increase in muscle strength observed in both treated patients to be a consequence of their treatment with RTX. To our knowledge, these are the first cases of increased muscle strength in patients with MM. Furthermore, the results of this study indicate that B cell depletion with RTX may be useful in the treatment of patients affected by MM, suggesting a possible role for B cells in the pathophysiology of this muscle disorder.

ABSTRACT Aims: Glucocorticoids are the sole drugs clinically used in Duchenne muscular dystrophy, in spite of the relevant side effects. Combination of glucocorticoids with synergistic drugs may be one strategy to lower doses and control side effects, meanwhile providing wider control of the complex pathology. This study is a pre-clinical evaluation of the effect of a combined treatment of alpha-methyl-prednisolone (PDN) with taurine, a safe aminoacid with positive effects on some pathology-related events. Methods: PDN (1 mg/kg/day i.p.) and taurine (1g/kg/day orally) were administered either alone or in combination, for 4-8 weeks to male dystrophic mdx mice chronically exercised on a treadmill. Effects were assessed in vivo and ex vivo with a variety of methodological approaches. Results: In vivo, each treatment significantly increased fore-limb strength, a marked synergistic effect being observed with the combination PDN+taurine. Ex vivo, PDN+taurine completely restored the mechanical threshold, an electrophysiological index of calcium homeostasis, of EDL myofibres and the benefit was greater than for PDN alone. In parallel, the over-activity of voltage-independent cation channels in dystrophic myofibres was reduced. No effects were observed on plasma levels of creatine kinase, while lactate dehydrogenase was decreased by taurine and, to a minor extent, by PDN + taurine. A similar histology profile was observed in PDN and PDN + taurine treated-muscles. PDN + taurine significantly increased taurine level in fast-twitch muscle and brain, by HPLC analysis. Conclusions: The combination PDN+taurine has additive actions on in vivo and ex vivo functional end-points, with less evident advantages on histopathology and biochemical markers of the disease.

Aberrant intracellular Ca(2+) regulation is believed to contribute to the development of cardiomyopathy in Duchenne muscular dystrophy. Here, we tested whether inhibition of protein kinase A (PKA) phosphorylation of ryanodine receptor type 2 (RyR2) prevents dystrophic cardiomyopathy by reducing SR Ca(2+) leak in the mdx mouse model of Duchenne muscular dystrophy. mdx mice were crossed with RyR2-S2808A mice, in which PKA phosphorylation site S2808 on RyR2 is inactivated by alanine substitution. Compared with mdx mice that developed age-dependent heart failure, mdx-S2808A mice exhibited improved fractional shortening and reduced cardiac dilation. Whereas application of isoproterenol severely depressed cardiac contractility and caused 95% mortality in mdx mice, contractility was preserved with only 19% mortality in mdx-S2808A mice. SR Ca(2+) leak was greater in ventricular myocytes from mdx than mdx-S2808A mice. Myocytes from mdx mice had a higher incidence of isoproterenol-induced diastolic Ca(2+) release events than myocytes from mdx-S2808A mice. Thus, inhibition of PKA phosphorylation of RyR2 reduced SR Ca(2+) leak and attenuated cardiomyopathy in mdx mice, suggesting that enhanced PKA phosphorylation of RyR2 at S2808 contributes to abnormal Ca(2+) homeostasis associated with dystrophic cardiomyopathy.

Duchenne muscular dystrophy (DMD) is the most common genetic muscle disease affecting 1 in 3,500 live male births. It is an X-linked recessive disease caused by a defective dystrophin gene. The disease is characterized by progressive limb weakness, respiratory and cardiac failure, and premature death. Fibrosis is a prominent pathological feature of muscle biopsies from patients with DMD. It directly causes muscle dysfunction and contributes to the lethal DMD phenotype. Although gene therapy and cell therapy may ultimately provide a cure for DMD, currently the disease is devastating, with no effective therapies. Recent studies have demonstrated that amelioratingmuscle fibrosis may represent a viable therapeutic approach for DMD. By reducing scar formation, antifibrotic therapies may not onlyimprove muscle function but also enhance muscle regeneration and promote gene and stem cell engraftment. Antifibrotic therapy mayserve as a necessary addition to gene and cell therapies to treat DMD in the future. Therefore, understanding cellular and molecular mechanisms underlying muscle fibrogenesis associated with dystrophin deficiency is key to the development of effective antifibrotic therapies for DMD.

The health-related quality of life of children with multiple sclerosis was compared with that of healthy children and of those with other neurologic diseases. The Pediatric Quality of Life Inventory Version 4.0 was administered to children with multiple sclerosis and clinically isolated syndrome and their parents (proxy reporters) at the University of California, San Francisco (UCSF), Regional Pediatric Multiple Sclerosis Center. Scores were compared with those of siblings and to those of children seen at the UCSF Pediatric Muscular Dystrophy Association Center. After adjustment for age and sex, children with multiple sclerosis or clinically isolated syndrome (P = 0.003) and their parents (P = 0.001) reported worse overall health-related quality of life than their siblings. Although overall scores for those with early multiple sclerosis or clinically isolated syndrome were better than for children with neuromuscular disease, their self-reported psychosocial scores were similar. The main predictor of reduced self-reported health-related quality of life among children with multiple sclerosis or clinically isolated syndrome was greater neurologic disability, whereas parents reported worse scores for girls, older children, and those with longer disease duration. Although it is better than for children with chronic neuromuscular diseases, children with multiple sclerosis or clinically isolated syndrome have substantial reductions in health-related quality of life. Copyright © 2010 Elsevier Inc. All rights reserved.