A Case of Myotonic Dystrophy Type I With Rimmed Vacuoles in Skeletal Muscle Pathology

IntroductionRimmed vacuolar myopathies (RVMs) are a group of genetically heterogeneous diseases that share histopathological characteristics on muscle biopsy, including the aberrant accumulation of autophagic vacuoles. However, the presence of non-coding sequences and structural mutations, some of which remain undetectable, confound the identification of pathogenic mutations responsible for RVMs. Therefore, we assessed the clinical profiles and muscle magnetic resonance imaging (MRI) changes in 36 Chinese patients with RVMs, emphasizing the role of muscle MRI in disease identification and differential diagnosis to propose a comprehensive literature-based imaging pattern to facilitate improved diagnostic workup.MethodsAll patients presented with rimmed vacuoles with varying degrees of muscular dystrophic changes and underwent a comprehensive evaluation using clinical, morphological, muscle MRI and molecular genetic analysis. We assessed muscle changes in the Chinese RVMs and provided an overview of the RVMs, focusing on the patterns of muscle involvement on MRI.ResultsA total of 36 patients, including 24 with confirmed distal myopathy and 12 with limb-girdle phenotype, had autophagic vacuoles with RVMs. Hierarchical clustering of patients according to the predominant effect of the distal or proximal lower limbs revealed that most patients with RVMs could be distinguished. GNE myopathy was the most prevalent form of RVMs observed in this study. Moreover, MRI helped identify the causative genes in some diseases (e.g., desminopathy and hereditary myopathy with early respiratory failure) and confirmed the pathogenicity of a novel mutation (e.g., adult-onset proximal rimmed vacuolar titinopathy) detected using next-generation sequencing.DiscussionCollectively, our findings expand our knowledge of the genetic spectrum of RVMs in China and suggest that muscle imaging should be an integral part of assisting genetic testing and avoiding misdiagnosis in the diagnostic workup of RVM.

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Quantitative proteomics analysis reveals the pathogenesis of obstructed defecation syndrome caused by abnormal expression of dystrophin

Li,

Xiong,

Wang

et al. 2024

World J Gastroenterol

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BACKGROUND Obstructed defecation syndrome (ODS) represents the most prevalent form of chronic constipation, affecting a diverse patient population, leading to numerous complications, and imposing a significant burden on healthcare resources. Most ODS patients have insufficient rectal propulsion, but the exact mechanism underlying the pathogenesis of ODS remains unclear. AIM To explore the molecular mechanism underlying the pathogenesis of ODS. METHODS A total of 30 pairs of rectal samples were collected from patients with ODS (ODS group) or grade IV prolapsed hemorrhoids without constipation (control group) for quantitative proteomic and bioinformatic analysis. Subsequently, 50 pairs of paraffin-embedded rectal specimens were selected for immunohistochemistry and immunofluorescence studies to validate the analysis results. Human intestinal smooth cell contractile function experiments and electrophysiological experiments were conducted to verify the physiological functions of target proteins. Cellular ultrastructure was detected using transmission electron microscopy. RESULTS In comparison to the control group, the expression level of dystrophin (DMD) in rectal specimens from ODS patients was markedly reduced. This finding was corroborated using immunohistochemistry and immunofluorescence techniques. The diminished expression of DMD compromised the contractile function of intestinal smooth muscle cells. At the molecular level, nucleoporin protein 153 and L-type voltage-gated calcium channel were found to be overexpressed in intestinal smooth muscle cells exhibiting downregulated DMD expression. Electrophysiological experiments confirmed an excessive influx of calcium ions into these cells. Moreover, vacuolar-like structures which may be associated with excessive calcium influx were observed in the cells by transmission electron microscopy. CONCLUSION Decreased DMD expression in intestinal smooth muscle may upregulate L-type voltage-gated calcium channel expression, leading to excessive calcium influx which may cause a decrease in rectal propulsion, thereby contributing to the pathogenesis of ODS.

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A Case of Myotonic Dystrophy Type I With Rimmed Vacuoles in Skeletal Muscle Pathology

Cited by 3 publications

References 2 publications

TLR4 activation inhibits the proliferation and osteogenic differentiation of skeletal muscle stem cells by downregulating LGI1

TLR4 activation inhibits the proliferation and osteogenic differentiation of skeletal muscle stem cells by downregulating LGI1

Clinical-pathological features and muscle imaging findings in 36 Chinese patients with rimmed vacuolar myopathies: case series study and review of literature

Quantitative proteomics analysis reveals the pathogenesis of obstructed defecation syndrome caused by abnormal expression of dystrophin

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