A cysteine 3340 substitution in the dystroglycan-binding domain of dystrophin associated with Duchenne muscular dystrophy, mental retardation and absence of the ERG b-wave

We report the first C-terminal missense mutation in a Duchenne muscular dystrophy patient. A G10227A transition of the dystrophin gene was found which resulted in the substitution of a highly conserved cysteine at position 3340 within the second half of the dystroglycan-binding domain. Residual amounts of 427 kDa dystrophin were detected in western blot analysis of the patient's muscle tissue, and immunohistological examination revealed weak traces of dystrophin on all fibers. Sarcolemmal staining intensity of 43 kDa beta-dystroglycan was also reduced. Mental retardation in our patient and absence of the b-wave in his electroretinogram indicate that central nervous functions of dystrophin isoforms also depend on the presence of cysteine 3340.      

The ZZ Domain of Dystrophin in DMD: Making Sense of Missense Mutations

Duchenne muscular dystrophy (DMD) is associated with the loss of dystrophin, which plays an important role in myofiber integrity via interactions with β‐dystroglycan and other members of the transmembrane dystrophin‐associated protein complex. The ZZ domain, a cysteine‐rich zinc‐finger domain near the dystrophin C‐terminus, is implicated in forming a stable interaction between dystrophin and β‐dystroglycan, but the mechanism of pathogenesis of ZZ missense mutations has remained unclear because not all such mutations have been shown to alter β‐dystroglycan binding in previous experimental systems. We engineered three ZZ mutations (p.Cys3313Phe, p.Asp3335His, and p.Cys3340Tyr) into a short construct similar to the Dp71 dystrophin isoform for in vitro and in vivo studies and delineated their effect on protein expression, folding properties, and binding partners. Our results demonstrate two distinct pathogenic mechanisms for ZZ missense mutations. The cysteine mutations result in diminished or absent subsarcolemmal expression because of protein instability, likely due to misfolding. In contrast, the aspartic acid mutation disrupts binding with β‐dystroglycan despite an almost normal expression at the membrane, confirming a role for the ZZ domain in β‐dystroglycan binding but surprisingly demonstrating that such binding is not required for subsarcolemmal localization of dystrophin, even in the absence of actin binding domains.     

Loss of the sarcoglycan complex and sarcospan leads to muscular dystrophy in beta-sarcoglycan-deficient mice.

beta-Sarcoglycan, one of the subunits of the sarcoglycan complex, is a transmembranous glycoprotein which associates with dystrophin and is the molecule responsible for beta-sarcoglycanopathy, a Duchenne-like autosomal recessive muscular dystrophy. To develop an animal model of beta-sarcoglycanopathy and to clarify the role of beta-sarcoglycan in the pathogenesis of the muscle degeneration in vivo, we developed beta-sarcoglycan-deficient mice using a gene targeting technique. beta-Sarcoglycan-deficient mice (BSG(-)(/-)mice) exhibited progressive muscular dystrophy with extensive degeneration and regeneration. The BSG(-)(/-)mice also exhibited muscular hypertrophy characteristic of beta-sarcoglycanopathy. Immunohistochemical and immunoblot analyses of BSG(-)(/-)mice demonstrated that deficiency of beta-sarcoglycan also caused loss of all of the other sarcoglycans as well as of sarcospan in the sarcolemma. On the other hand, laminin-alpha2, alpha- and beta-dystroglycan and dystrophin were still present in the sarcolemma. However, the dystrophin-dystroglycan complex in BSG(-)(/-)mice was unstable compared with that in the wild-type mice. Our data suggest that loss of the sarcoglycan complex and sarcospan alone is sufficient to cause muscular dystrophy, that beta-sarcoglycan is an important protein for formation of the sarcoglycan complex associated with sarcospan and that the role of the sarcoglycan complex and sarcospan may be to strengthen the dystrophin axis connecting the basement membrane with the cytoskeleton.     

Chylomicronemia mutations yield new insights into interactions between lipoprotein lipase and GPIHBP1

Lipoprotein lipase (LPL) is a 448-amino-acid head-to-tail dimeric enzyme that hydrolyzes triglycerides within capillaries. LPL is secreted by parenchymal cells into the interstitial spaces; it then binds to GPIHBP1 (glycosylphosphatidylinositol-anchored high density lipoprotein-binding protein 1) on the basolateral face of endothelial cells and is transported to the capillary lumen. A pair of amino acid substitutions, C418Y and E421K, abolish LPL binding to GPIHBP1, suggesting that the C-terminal portion of LPL is important for GPIHBP1 binding. However, a role for LPL's N terminus has not been excluded, and published evidence has suggested that only full-length homodimers are capable of binding GPIHBP1. Here, we show that LPL's C-terminal domain is sufficient for GPIHBP1 binding. We found, serendipitously, that two LPL missense mutations, G409R and E410V, render LPL susceptible to cleavage at residue 297 (a known furin cleavage site). The C terminus of these mutants (residues 298-448), bound to GPIHBP1 avidly, independent of the N-terminal fragment. We also generated an LPL construct with an in-frame deletion of the N-terminal catalytic domain (residues 50-289); this mutant was secreted but also was cleaved at residue 297. Once again, the C-terminal domain (residues 298-448) bound GPIHBP1 avidly. The binding of the C-terminal fragment to GPIHBP1 was eliminated by C418Y or E421K mutations. After exposure to denaturing conditions, the C-terminal fragment of LPL refolds and binds GPIHBP1 avidly. Thus, the binding of LPL to GPIHBP1 requires only the C-terminal portion of LPL and does not depend on full-length LPL homodimers.     

Internal deletion compromises the stability of dystrophin

Duchenne muscular dystrophy (DMD) is a deadly and common childhood disease caused by mutations that disrupt dystrophin protein expression. Several miniaturized dystrophin/utrophin constructs are utilized for gene therapy, and while these constructs have shown promise in mouse models, the functional integrity of these proteins is not well described. Here, we compare the biophysical properties of full-length dystrophin and utrophin with therapeutically relevant miniaturized constructs using an insect cell expression system. Full-length utrophin, like dystrophin, displayed a highly cooperative melting transition well above 37°C. Utrophin constructs involving N-terminal, C-terminal or internal deletions were remarkably stable, showing cooperative melting transitions identical to full-length utrophin. In contrast, large dystrophin deletions from either the N- or C-terminus exhibited variable stability, as evidenced by melting transitions that differed by 20°C. Most importantly, deletions in the large central rod domain of dystrophin resulted in a loss of cooperative unfolding with increased propensity for aggregation. Our results suggest that the functionality of dystrophin therapeutics based on mini- or micro-constructs may be compromised by the presence of non-native protein junctions that result in protein misfolding, instability and aggregation.     

Is the maintainance of the C-terminus domain of dystrophin enough to ensure a milder Becker muscular dystrophy phenotype?

The severe Duchenne muscular dystrophy (DMD) and the more benignBecker type (BMD) are allelic conditions, controlled by a defectivegene at Xp21, caused by the absence (DMD) or a defect in quantityor quality (BMD) of the protein dystrophin. It has been suggestedthat the C-terminus domain of dystrophin is fundamental to ensurethe proper protein sub-cellular localization and function. Wewish to report our dystrophin findings in 4 among 142 DMD patientsstudied for DNA deletions and dystrophin analysis. Althoughthey have a severe clinical course, a positive dystrophin immunofluorescencepattern was seen using C-terminal antibody, and a dystrophinband of reduced molecular weight (corresponding to their DNAdeletions), but which maintained the C-terminus was seen throughWestern blot (WB). Based on these findings, we suggest thatin order to partially maintain its function, resulting in amilder phenotype, dystrophin may carry large internal deletionsbut in addition to the C-terminus, the region encompassing boththe N-terminus and the proximal region of the rod domain cannotbe absent. Therefore, the prognosis of a Becker phenotype ina young patient should be done with caution if based only onthe presence or not of dystrophin.     

Processing of beta-dystroglycan by matrix metalloproteinase disrupts the link between the extracellular matrix and cell membrane via the dystroglycan complex

The dystroglycan complex is a membrane-spanning complex composed of two subunits, alpha- and beta-dystroglycan. alpha-dystroglycan is a cell surface peripheral membrane protein which binds to the extracellular matrix (ECM), whereas beta-dystroglycan is an integral membrane protein which anchors alpha-dystroglycan to the cell membrane. The dystroglycan complex provides a tight link between the ECM and cell membrane. Dysfunction of the dystroglycan complex has commonly been implicated in the molecular pathogenesis of severe forms of hereditary neuromuscular diseases, including Duchenne muscular dystrophy, Fukuyama-type congenital muscular dystrophy and sarcoglycanopathy (LGMD2C, -D, -E and -F). To begin to clarify the pathway by which the dysfunction of the dystroglycan complex could lead to muscle cell degeneration, we investigated the proteolytic processing of the dystroglycan complex in this study. We demonstrate that (i) a 30 kDa fragment of beta-dystroglycan is expressed in peripheral nerve, kidney, lung and smooth muscle, but not skeletal muscle, cardiac muscle or brain, and (ii) this fragment is the product of proteolytic processing of the extracellular domain of beta-dystroglycan by the membrane-associated matrix metalloproteinase (MMP) activity. Importantly, furthermore, we demonstrate that this processing disintegrates the dystroglycan complex. Our results indicate that the processing of beta-dystroglycan by MMP causes the disruption of the link between the ECM and cell membrane via the dystroglycan complex, which could have profound effects on cell viability. Based on these and previously reported findings, we propose a hypothesis that this processing may play a crucial role in the molecular pathogenesis of sarcoglycanopathy.     

Five novel androgen receptor gene mutations associated with complete androgen insensitivity syndrome

Mutations in the androgen receptor (AR) gene result in androgen insensitivity syndrome (AIS). We have identified five novel mutations that result in a complete loss in AR function and are associated with complete AIS. The mutations span all three AR major functional domains. In two cases, the loss of AR function could be explained on the basis of the current knowledge of AR molecular structure and function. N-terminal mutation c.256C>T (p.Gln86X) leads to an early stop codon and abolishes all DNA and ligand binding. The DNA-binding domain mutation c.1685G>A (p.Cys562Tyr) is located in the N-terminal part of the first zinc finger; a mutation in this position is likely to impair the association of the mutated AR with the androgen response element of target genes. The splice site mutation at intron 2/exon 3 junction (c.1766-1G>A) is shown to lead to c.1765_1766 ins69 (p.[Gly589_Lys590ins23;Gly589Glu]). The two novel ligand-binding domain mutations identified were recreated by site-directed mutagenesis. Both mutations c.2171G>T (p.Gly724Val) and c.2435T>C (p.Leu812Pro) abolished AR ligand binding and severely impaired AR mediated transactivation. Residue p.Gly724 is located in the ligand binding domain, between helices 3 and 4. This region is known to be involved not only in ligand binding but also in AR N/C-terminal interactions. The mutation p.Leu812Pro is located in the C-terminal end of helix 8. This domain is highly conserved and critical for ligand binding. This study extends current understanding of AR mutations associated with CAIS.     

Spectrin-like repeats from dystrophin and alpha-actinin-2 are not functionally interchangeable

Mutations in the dystrophin gene result in Duchenne muscular dystrophy (DMD). Dystrophin is a multidomain protein that functions to stabilize the sarcolemmal membrane during muscle contraction. The central rod domain has been proposed to act as a shock absorber, as a force transducer or as a spacer separating important N- and C-terminal domains that interact with actin and the dystrophin-glycoprotein complex (DGC). Structure/function studies demonstrated that deletion of large portions of the rod domain can result in the production of smaller, yet highly functional, dystrophin proteins. In a dramatic example, a 'micro-dystrophin' transgene containing only four dystrophin spectrin-like repeats resulted in complete correction of most of the symptoms associated with dystrophy in the mdx mouse model for DMD. Dystrophin shares considerable homology with the multidomain, actin-crosslinking protein alpha-actinin. To explore the hypothesis that the dystrophin rod domain acts as a spacer region, a chimeric micro-dystrophin transgene containing the four-repeat rod domain of alpha-actinin-2 was expressed in mdx mice. This chimeric transgene was incapable of correcting the morphological pathology of the mdx mouse, but still functioned to assemble the DGC at the membrane and provided some protection from contraction-induced injury. These data demonstrated that different spectrin-like repeats are not equivalent, and reinforced the suggestion that the dystrophin rod domain is not merely a spacer but likely contributes an important mechanical role to overall dystrophin function.     

Mini-dystrophin efficiently incorporates into the dystrophin protein complex in living cells

Dystrophin is a critical muscle cell structural protein which when deficient results in Duchenne muscular dystrophy. Recently miniature versions of the dystrophin gene have been constructed that ameliorate the pathology in mouse models. To characterize mini-dystrophin’s incorporation into the dystrophin protein complex in living cells, two fusion proteins were constructed where mini-dystrophin is fused to the N- or C-terminus of an enhanced green fluorescent protein reporter gene. Both fusion proteins correctly localize at the plasma membrane in vitro and in vivo. Live cell microscopy establishes that mini-dystrophin translocates directly to the PM of differentiating muscle cells, within 4 h of expression. Latrunculin A treatment, actin and β-dystroglycan binding domain deletion constructs, and co-immunoprecipitation assays demonstrate that mini-dystrophin is firmly anchored to the sarcolemma primarily through its connections to β-dystroglycan, mimicking effects seen with wild type dystrophin. Furthermore, point mutations made within the putative β-dystroglycan anchoring ZZ domain of mini-dystrophin result in an ablation of β-dystroglycan binding and a nuclear translocation of the protein. These results demonstrate that mini-dystrophin is efficiently bound and incorporated into the dystrophin protein complex, via β-dystroglycan in living cells, similarly to the full length dystrophin protein.Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

Additional dystrophin fragment in Becker muscular dystrophy may result from proteolytic cleavage at deletion junctions.

Becker muscular dystrophy is usually caused by intragenic dystrophin gene deletions that result in production of an internally deleted protein. Previous studies have detected what appears to be a unique dystrophin degradation product that appears only in muscle biopsies from patients with Becker muscular dystrophy. This dystrophin fragment is always seen in addition to the "full-size" dystrophin of the expected size for a given gene deletion. It is only found in biopsies from patients with mutations in the deletion-prone region encompassing exons 45-53, but it does not appear to correlate with any observable phenotype at the clinical level. By correlating the size and locations of dystrophin gene deletions with the size of this degradation product, together with use of region-specific dystrophin antisera, we find that proteolytic cleavage may occur at the deletion breakpoints, perhaps due to alterations of the secondary and/or tertiary structures of the protein. This cleavage results in loss of the carboxy-terminal domains that are thought to be important for interactions between dystrophin and other membrane-bound proteins.     

Localization of Functional Domains of the Mitogenic Toxin of Pasteurella multocida

The locations of the catalytic and receptor-binding domains of the Pasteurella multocida toxin (PMT) were investigated. N- and C-terminal fragments of PMT were cloned and expressed as fusion proteins with affinity tags. Purified fusion proteins were assessed in suitable assays for catalytic activity and cell-binding ability. A C-terminal fragment (amino acids 681 to 1285) was catalytically active. When microinjected into quiescent Swiss 3T3 cells, it induced changes in cell morphology typical of toxin-treated cells and stimulated DNA synthesis. An N-terminal fragment with a His tag at the C terminus (amino acids 1 to 506) competed with full-length toxin for binding to surface receptors and therefore contains the cell-binding domain. The inactive mutant containing a mutation near the C terminus (C1165S) also bound to cells in this assay. Polyclonal antibodies raised to the N-terminal PMT region bound efficiently to full-length native toxin, suggesting that the N terminus is surface located. Antibodies to the C terminus of PMT were microinjected into cells and inhibited the activity of toxin added subsequently to the medium, confirming that the C terminus contains the active site. Analysis of the PMT sequence predicted a putative transmembrane domain with predicted hydrophobic and amphipathic helices near the N terminus over the region of homology to the cytotoxic necrotizing factors. The C-terminal end of PMT was predicted to be a mixed alpha/beta domain, a structure commonly found in catalytic domains. Homology to proteins of known structure and threading calculations supported these assignments.     

Additional dystrophin fragment in Becker muscular dystrophy may result from proteolytic cleavage at deletion junctions

Becker muscular dystrophy is usually caused by intragenic dystrophin gene deletions that result in production of an internally deleted protein. Previous studies have detected what appears to be a unique dystrophin degradation product that appears only in muscle biopsies from patients with Becker muscular dystrophy. This dystrophin fragment is always seen in addition to the “full-size” dystrophin of the expected size for a given gene deletion. It is only found in biopsies from patients with mutations in the deletion-prone region encompassing exons 45–53, but it does not appear to correlate with any observable phenotype at the clinical level. By correlating the size and locations of dystrophin gene deletions with the size of this degradation product, together with use of region-specific dystrophin antisera, we find that proteolytic cleavage may occur at the deletion breakpoints, perhaps due to alterations of the secondary and/or tertiary structures of the protein. This cleavage results in loss of the carboxy-terminal domains that are thought to be important for interactions between dystrophin and other membrane-bound proteins. © Wiley-Liss, Inc.     

A highly functional mini-dystrophin/GFP fusion gene for cell and gene therapy studies of Duchenne muscular dystrophy

A promising approach for treating Duchenne muscular dystrophy (DMD) is by autologous cell transplantation of myogenic stem cells transduced with a therapeutic expression cassette. Development of this method has been hampered by a low frequency of cellular engraftment, the difficulty of tracing transplanted cells, the rapid loss of autologous cells carrying marker genes that are unable to halt muscle necrosis and the difficulty of stable transfer of a large dystrophin gene into myogenic stem cells. We engineered a 5.7 kb miniDys-GFP fusion gene by replacing the dystrophin C-terminal domain (DeltaCT) with an eGFP coding sequence and removing much of the dystrophin central rod domain (DeltaH2-R19). In a transgenic mdx(4Cv) mouse expressing the miniDys-GFP fusion protein under the control of a skeletal muscle-specific promoter, the green fusion protein localized on the sarcolemma, where it assembled the dystrophin-glycoprotein complex and completely prevented the development of dystrophy in transgenic mdx(4Cv) muscles. When myogenic and other stem cells from these mice were transplanted into mdx(4Cv) recipients, donor cells can be readily identified in skeletal muscle by direct green fluorescence or by using antibodies against GFP or dystrophin. In mdx(4Cv) mice reconstituted with bone marrow cells from the transgenic mice, we monitored engraftment in various muscle groups and found the number of miniDys-GFP(+) fibers increased with time. We suggest that these transgenic mdx(4Cv) mice are highly useful for developing autologous cell therapies for DMD.     

计算机三维重构验证Dystrophin疏水区段与Duchenne型肌营养不良的发病

背景：Duchenne型肌营养不良和Becker型进行性肌营养不良都是dystrophin基因突变所致,但后者临床表型较轻。“阅读框规则”可解释大部分基因型与临床型关系,但累及疏水区段的整码突变也可导致Duchenne型肌营养不良。因此很有必要了解疏水区域在dystrophin中的功能,且这些疏水区段的三维结构及功能在发病机制中所起的具体作用仍未阐明。 目的：通过Kyte&Doolittle平均疏水轮廓分析研究dystrophin的疏水区段。利用swiss-model三维重构dystrophin的疏水区段阐述其在发病机制中所起的作用。 方法：参考莱顿开放数据库(http://www.dmd.nl/)及收集中山大学附属第一医院2002年至2013年确诊Duchenne型进行性肌营养不良或Becker型进行性肌营养不良的缺失型整码突变患者资料共1 038例,分析其临床型与基因型关系。使用bioedit软件计算dystrophin的平均疏水轮廓及利用swiss-model三维重构疏水区段,结合临床型和基因型关系确定dystrophin重要功能区。 结果与结论：dystrophin存在4个疏水区段,分别为肌动蛋白结合区内的Calponin同源区2、中央棒区内的重复区16、第三铰链区和EF手型区。第1,2,4疏水区段是dystrophin糖蛋白复合物中dystrophin与其他糖蛋白的结合区域,其破坏严重影响dystrophin糖蛋白复合物功能,临床症状重。中央棒区在第三铰链区附近断裂后,HⅢ的无规则卷结构不容易与断端重复区的螺旋结构恢复连接。但第三铰链区同时缺失,其两端的重复区较容易重新连接,所以第3疏水区破坏后其临床症状反而较轻。提示dystrophin的疏水区段是其重要功能区,多是dystrophin糖蛋白复合物中dystrophin与相关蛋白的结合部位,在Duchenne型肌营养不良的发病机制中起重要作用。 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程全文链接：     

Expression of Dp260 in muscle tethers the actin cytoskeleton to the dystrophin-glycoprotein complex and partially prevents dystrophy

Dystrophin forms a mechanical link between the actin cytoskeleton and the extracellular matrix in muscle that helps maintain sarcolemmal integrity. Two regions of dystrophin have been shown to bind actin: the N-terminal domain and rod domain repeats 11-17. To better understand the roles of these two domains and whether the rod domain actin-binding domain alone can support a mechanically functional link with actin, we constructed transgenic mice expressing Dp260 in skeletal muscle. Dp260, the retinal isoform of dystrophin, lacks the N-terminal domain and a significant portion of the rod domain, but retains the rod domain actin-binding domain. Our results indicate that Dp260 expression restores a stable association between costameric actin and the sarcolemma, assembles the dystrophin-glycoprotein complex, and significantly slows the progression of the dystrophy in the dystrophin-deficient mdx mouse. We assessed the functional integrity of the mechanical link in Dp260 transgenic mdx mice and found that Dp260 muscles showed normal resistance to contraction-induced injury, but dramatic reductions in force generation similar to those found with mdx muscles. Morphologically, Dp260 muscles displayed reduced amounts of inflammation and fibrosis, but still showed a significant, albeit reduced, amount of degeneration/regeneration. These data demonstrate that protection from contraction-induced injury can dramatically ameliorate, but not completely halt, the dystrophic process. We suggest that a non-mechanical defect, attributed to the loss of the N terminus of dystrophin, is likely responsible for the residual dystrophy observed.     

Dystrophin and utrophin influence fiber type composition and post-synaptic membrane structure

The X-linked muscle wasting disease Duchenne muscular dystrophy is caused by the lack of dystrophin in muscle. Protein structure predictions, patient mutations, in vitro binding studies and transgenic and knockout mice suggest that dystrophin plays a mechanical role in skeletal muscle, linking the subsarcolemmal cytoskeleton with the extracellular matrix through its direct interaction with the dystrophin-associated protein complex (DAPC). Although a signaling role for dystrophin has been postulated, definitive data have been lacking. To identify potential non-mechanical roles of dystrophin, we tested the ability of various truncated dystrophin transgenes to prevent any of the skeletal muscle abnormalities associated with the double knockout mouse deficient for both dystrophin and the dystrophin-related protein utrophin. We show that restoration of the DAPC with Dp71 does not prevent the structural abnormalities of the post-synaptic membrane or the abnormal oxidative properties of utrophin/dystrophin-deficient muscle. In marked contrast, a dystrophin protein lacking the cysteine-rich domain, which is unable to prevent dystrophy in the mdx mouse, is able to ameliorate these abnormalities in utrophin/dystrophin-deficient mice. These experiments provide the first direct evidence that in addition to a mechanical role and relocalization of the DAPC, dystrophin and utrophin are able to alter both structural and biochemical properties of skeletal muscle. In addition, these mice provide unique insights into skeletal muscle fiber type composition.     

Clinical and pathological characteristics of four Korean patients with limb-girdle muscular dystrophy type 2B

Limb-girdle muscular dystrophy type 2B (LGMD2B), a subtype of autosomal recessive limb-girdle muscular dystrophy (ARLGMD), is characterized by a relatively late onset and slow progressive course. LGMD2B is known to be caused by the loss of the dysferlin protein at sarcolemma in muscle fibers. In this study, the clinical and pathological characteristics of Korean LGMD2B patients were investigated. Seventeen patients with ARLGMD underwent muscle biopsy and the histochemical examination was performed. For the immunocytochemistry, a set of antibodies against dystrophin, alpha, beta, gamma, delta-sarcoglycans, dysferlin, caveolin-3, and beta-dystroglycan was used. Four patients (24%) showed selective loss of immunoreactivity against dysferlin at the sarcolemma on the muscle specimens. Therefore, they were classified into the LGMD2B category. The age at the onset of disease ranged from 9 yr to 33 yr, and none of the patients was wheelchair bound at the neurological examination. The serum creatine kinase (CK) was high in all the patients (4010-5310 IU/L). The pathologic examination showed mild to moderate dystrophic features. These are the first Korean LGMD2B cases with a dysferlin deficiency confirmed by immunocytochemistry. The clinical, pathological, and immunocytochemical findings of the patients with LGMD2B in this study were in accordance with those of other previous reports.