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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Emery-Dreifuss muscular dystrophy is an X-linked neuromuscular disorder caused by defects in the STA gene on Xq28, which codes for a nuclear protein named emerin. Affected patients usually present in early adolescence with scapulo-peroneal muscle weakness and wasting, and contractures of the tendo Achilles, elbows and paraspinal muscles, resulting in spine rigidity. We present here a case of Emery-Dreifuss muscular dystrophy with an unusually severe, early presentation. He presented at 2.5 years with predominantly proximal weakness and mild equinovarus deformity of the right foot. Serum creatine kinase activity was elevated (1994 IU/I) and a muscle biopsy at the age of 4 years showed marked dystrophic abnormalities. Normal expression of dystrophin, and no detectable deletion in the corresponding gene, excluded a diagnosis of Duchenne muscular dystrophy. Similarly, normal expression of alpha-sarcoglycan made a limb-girdle muscular dystrophy caused by a defect in a sarcoglycan unlikely. Several years later, examination of the proband's maternal cousin, aged 14 years, suggested Emery-Dreifuss muscular dystrophy. This was confirmed in both affected boys by the absence of emerin in muscle and leucocytes, and identification of a mutation in exon 4 of the STA gene. Carrier status in both mothers was also confirmed by mutational and protein analysis. Emery-Dreifuss muscular dystrophy should therefore be considered in the differential diagnosis of cases of early onset muscular dystrophy, even in the absence of the typical clinical features.
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PMID:Early presentation of X-linked Emery-Dreifuss muscular dystrophy resembling limb-girdle muscular dystrophy. 960 59

Emerin encoded by the STA gene is the first nuclear protein linked with a muscular dystrophy. Emerin is a 34 kDa, predominantly hydrophilic protein with a single hydrophobic region supposed to serve as a transmembrane domain. It was classified as a type II integral membrane protein localized at the inner nuclear membrane/nuclear lamina with an ubiquitous tissue distribution. It is speculated that emerin is required for the stability and normal function of rigorously moving nuclei in skeletal muscle and heart. During mitosis, emerin is cell-cycle-dependent phosphorylated and shows stage-dependent changes in distribution and localization suggesting that it plays a role in re-assembly of nuclear membranes. Mutations of the emerin gene have been associated with X-linked Emery-Dreifuss muscular dystrophy clinically defined by early joint contractures, progressive muscle weakness, and cardiomyopathy. Hopefully, identification of the protein defect may promote new therapeutic strategies concerning muscle fiber development and stability.
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PMID:Emerin. 1053 81

Our understanding of the neuromuscular disorders of childhood has been rapidly expanding. This is mostly because of the discovery of the underlying genetic loci for the vast majority of these diseases and the abnormal proteins produced caused by these mutations. Spinal muscular atrophy is the second most frequent autosomal recessive disease of childhood and the most fatal. It has been mapped to chromosome 5q11.2-13.3, an area with three distinct genes associated with spinal muscular atrophy. Charcot-Marie-Tooth is the most common inherited peripheral neuropathy. Three genes encoding for myelin proteins and one for a nuclear protein have been associated with this group of disorders. Finally, since dystrophin was cloned in 1986, many proteins assisting dystrophin in anchoring the muscle cytoskeleton to the extracellular matrix have been discovered. Mutations in these genes lead to various forms of muscular dystrophy.
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PMID:Genetics of pediatric neuromuscular disease. 1110 73

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant neuromuscular disorder that is not due to a classical mutation within a protein-coding gene. Instead, almost all FSHD patients carry deletions of an integral number of tandem 3.3-kilobase repeat units, termed D4Z4, located on chromosome 4q35 (ref. 3). D4Z4 contains a transcriptional silencer whose deletion leads to inappropriate overexpression in FSHD skeletal muscle of 4q35 genes located upstream of D4Z4 (ref. 4). To identify the gene responsible for FSHD pathogenesis, we generated transgenic mice selectively overexpressing in skeletal muscle the 4q35 genes FRG1, FRG2 or ANT1. We find that FRG1 transgenic mice develop a muscular dystrophy with features characteristic of the human disease; by contrast, FRG2 and ANT1 transgenic mice seem normal. FRG1 is a nuclear protein and several lines of evidence suggest it is involved in pre-messenger RNA splicing. We find that in muscle of FRG1 transgenic mice and FSHD patients, specific pre-mRNAs undergo aberrant alternative splicing. Collectively, our results suggest that FSHD results from inappropriate overexpression of FRG1 in skeletal muscle, which leads to abnormal alternative splicing of specific pre-mRNAs.
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PMID:Facioscapulohumeral muscular dystrophy in mice overexpressing FRG1. 1634 Dec 2

The Emery-Dreifuss muscular dystrophy is a form of muscular dystrophy that frequently presents early contractures and cardiac conduction defects, caused by emerin deficiency in the inner nuclear membrane of the muscular fibers. A 19-years-old man it presented muscle weakness and hypotrophy in the proximal upper and lower limbs, dysphagia and early contractures in elbows and ankles, with familiar history compatible with X-linked inheritance form. The investigation showed increased serum creatinekinase levels electrocardiogram had a first degree atrioventricular block and right bundle branch block normal electromyography and nerve conduction study muscle biopsy disclosed myopathic characteristics and nuclear protein immunohystochemical analysis showed deficiency of emerin. The clinical and genetics manifestations, laboratorial and electromyography changes, as well as, the study of the pattern of inheritance for genetic counseling are discussed.
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PMID:[Emery-Dreifuss muscular dystrophy: case report]. 1679 77

Lamins are intermediate filament proteins that form a scaffold, termed nuclear lamina, at the nuclear periphery. A small fraction of lamins also localize throughout the nucleoplasm. Lamins bind to a growing number of nuclear protein complexes and are implicated in both nuclear and cytoskeletal organization, mechanical stability, chromatin organization, gene regulation, genome stability, differentiation, and tissue-specific functions. The lamin-based complexes and their specific functions also provide insights into possible disease mechanisms for human laminopathies, ranging from muscular dystrophy to accelerated aging, as observed in Hutchinson-Gilford progeria and atypical Werner syndromes.
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PMID:Lamins: nuclear intermediate filament proteins with fundamental functions in nuclear mechanics and genome regulation. 2574 1

Duchenne muscular dystrophy (DMD) is a genetic disorder in which the absence of dystrophin leads to progressive muscle degeneration and weakness. Although the genetic basis is known, the pathophysiology of dystrophic skeletal muscle remains unclear. We examined nuclear movement in wild-type (WT) and muscular dystrophy mouse model for DMD (MDX) (dystrophin-null) mouse myofibers. We also examined expression of proteins in the linkers of nucleoskeleton and cytoskeleton (LINC) complex, as well as nuclear transcriptional activity via histone H3 acetylation and polyadenylate-binding nuclear protein-1. Because movement of nuclei is not only LINC dependent but also microtubule dependent, we analyzed microtubule density and organization in WT and MDX myofibers, including the application of a unique 3D tool to assess microtubule core structure. Nuclei in MDX myofibers were more mobile than in WT myofibers for both distance traveled and velocity. MDX muscle shows reduced expression and labeling intensity of nesprin-1, a LINC protein that attaches the nucleus to the microtubule and actin cytoskeleton. MDX nuclei also showed altered transcriptional activity. Previous studies established that microtubule structure at the cortex is disrupted in MDX myofibers; our analyses extend these findings by showing that microtubule structure in the core is also disrupted. In addition, we studied malformed MDX myofibers to better understand the role of altered myofiber morphology vs. microtubule architecture in the underlying susceptibility to injury seen in dystrophic muscles. We incorporated morphological and microtubule architectural concepts into a simplified finite element mathematical model of myofiber mechanics, which suggests a greater contribution of myofiber morphology than microtubule structure to muscle biomechanical performance.NEW & NOTEWORTHY Microtubules provide the means for nuclear movement but show altered organization in the muscular dystrophy mouse model (MDX) (dystrophin-null) muscle. Here, MDX myofibers show increased nuclear movement, altered transcriptional activity, and altered linkers of nucleoskeleton and cytoskeleton complex expression compared with healthy myofibers. Microtubule architecture was incorporated in finite element modeling of passive stretch, revealing a role of fiber malformation, commonly found in MDX muscle. The results suggest that alterations in microtubule architecture in MDX muscle affect nuclear movement, which is essential for muscle function.
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PMID:Altered nuclear dynamics in MDX myofibers. 2797 87