Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene, leading to the absence of the dystrophin protein in striated muscle. A significant number of these mutations are premature stop codons. On the basis of the observation that aminoglycoside treatment can suppress stop codons in cultured cells, we tested the effect of gentamicin on cultured muscle cells from the mdx mouse - an animal model for DMD that possesses a premature stop codon in the dystrophin gene. Exposure of mdx myotubes to gentamicin led to the expression and localization of dystrophin to the cell membrane. We then evaluated the effects of differing dosages of gentamicin on expression and functional protection of the muscles of mdx mice. We identified a treatment regimen that resulted in the presence of dystrophin in the cell membrane in all striated muscles examined and that provided functional protection against muscular injury. To our knowledge, our results are the first to demonstrate that aminoglycosides can suppress stop codons not only in vitro but also in vivo. Furthermore, these results raise the possibility of a novel treatment regimen for muscular dystrophy and other diseases caused by premature stop codon mutations. This treatment could prove effective in up to 15% of patients with DMD.
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PMID:Aminoglycoside antibiotics restore dystrophin function to skeletal muscles of mdx mice. 1044 26

Duchenne muscular dystrophy (DMD), with an incidence of one in 3500 male new borns, and its milder variant, Becker muscular dystrophy (BMD), are allelic X-linked recessive disorders, caused by mutations in the gene coding for dystrophin, a 427 kD cytoskeleton protein. There are no available molecular markers to differentiate these two. The purpose of this study was to study genetic polymorphism in muscular dystrophy and explore its potential in discriminating these two allelic forms of the disease. The results revealed unambiguously the presence of three transcripts : 598bp, 849bp and 1583bp long which are selectively expressed in the muscles afflicted with muscular dystrophy as compared to the normal muscle. 1583bp gene transcript was conspicuously present in the muscle tissues of both DMD and BMD patients whereas 598bp and 849bp long transcripts were exclusively present in DMD but not in BMD patients or normal human subjects. These gene transcripts had no sequence homology with dystrophin gene and these were also present in the families belonging to DMD and BMD patients. These results point to the fact that based upon the selective expression of these three gene transcripts, one could not only differentiate between DMD and BMD diseases at the molecular level, but also between normal and dystrophic muscle. Further, these findings also reveal that apart from dystrophin gene, these gene transcripts may also be responsible for the differential progression of DMD/BMD phenotype.
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PMID:Genetic polymorphism in muscle biopsies of Duchenne and Becker muscular dystrophy patients. 1051 83

Ten different mutations have been identified in patients with Becker (n = 1) or Duchenne (n = 9) muscular dystrophy using reverse transcription of total RNA, polymerase chain reaction amplification of the whole coding region of the gene and protein truncation test (PTT) analysis. Seven mutations had not been reported previously, and these consist in three nonsense mutations (Q2522X, E2726X, R3381X), three frameshifting deletions (3686-3687delGT, 5126delA, 5759delC), and four splicing defects of which the effects on the muscle dystrophin mRNA transcripts have been analyzed. In one case, a 3' splice-site mutation (IVS74-2A-->G) resulted in a complex pattern of exon skipping involving exons of the C-terminal domain. In the three other cases, nucleotide substitutions in splice donor (IVS26+2T-->A, IVS65+1G-->A) or acceptor (IVS8-15A-->G) recognition sequences led to the use of cryptic splice sites, with consequent insertions of intronic sequences in the processed mRNA. Up to 34% (70/203) of the point mutations reported to date in the dystrophin database (http://www.dmd.nl) affect splice sites of the dystrophin gene. However, altered mRNA splicing has been confirmed experimentally in only 23% of cases (16/70). Combined with PTT, the transcript analysis protocol defined in this study permits direct determination of the impact of intronic variations on the structure of dystrophin mRNA and of the resulting consequences on the translational reading frame. We present evidence for a frequent use of cryptic splice sites as a result of splicing defects.
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PMID:Point mutations in the dystrophin gene: evidence for frequent use of cryptic splice sites as a result of splicing defects. 1053 61

Mutations in the dystrophin gene (DMD) and in genes encoding several dystrophin-associated proteins result in Duchenne and other forms of muscular dystrophy. alpha-Dystroglycan (Dg) binds to laminins in the basement membrane surrounding each myofibre and docks with beta-Dg, a transmembrane protein, which in turn interacts with dystrophin or utrophin in the subplasmalemmal cytoskeleton. alpha- and beta-Dgs are thought to form the functional core of a larger complex of proteins extending from the basement membrane to the intracellular cytoskeleton, which serves as a superstructure necessary for sarcolemmal integrity. Dgs have also been implicated in the formation of synaptic densities of acetylcholine receptors (AChRs) on skeletal muscle. Here we report that chimaeric mice generated with ES cells targeted for both Dg alleles have skeletal muscles essentially devoid of Dgs and develop a progressive muscle pathology with changes emblematic of muscular dystrophies in humans. In addition, many neuromuscular junctions are disrupted in these mice. The ultrastructure of basement membranes and the deposition of laminin within them, however, appears unaffected in Dg-deficient muscles. We conclude that Dgs are necessary for myofibre survival and synapse differentiation or stability, but not for the formation of the muscle basement membrane, and that Dgs may have more than a purely structural function in maintaining muscle integrity.
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PMID:Chimaeric mice deficient in dystroglycans develop muscular dystrophy and have disrupted myoneural synapses. 1054 34

Duchenne and Becker muscular dystrophies are X-linked allelic disorders in which the association of central nervous system dysfunction, typically in the form of mental retardation, is a well recognized feature. They are both due to mutations in the dystrophin gene, whose corresponding protein products are expressed both in the muscle and central nervous system. We have observed an increased frequency of epilepsy in children with Duchenne and Becker muscular dystrophy attending our clinic. Out of 254 boys with this condition (201 Duchenne and 53 Becker), eight children, four in the Duchenne and four in the Becker group, had a confirmed diagnosis of epilepsy (cumulative incidence 3.14%, with a subgroup incidence of 1.99% in the Duchenne and 7.54% in the Becker group). Statistical analysis indicated that only the incidence of epilepsy in Becker muscular dystrophy was significant (p < 0.007). Our data suggests that epilepsy may be a rare associated feature in children with muscular dystrophy secondary to dystrophin deficiency.
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PMID:Epilepsy in Duchenne and Becker muscular dystrophies. 1072 5

A man was identified with two X-chromosomal neuromuscular disorders, X-linked Charcot-Marie-Tooth disease (CMTX) and Becker muscular dystrophy (BMD). The neuropathy could be tracked in the family and was found to be caused by a mutation in the connexin32 gene on Xq13. 1. The muscular dystrophy was sporadic owing to a de novo deletion in the dystrophin gene located in band Xp21.2. Although these genetic alterations of the same X-chromosome are considered as physically independent, their combination resulted in a unique phenotype with severe wasting of proximal as well as distal muscles and rapid progression of both conditions.
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PMID:Becker muscular dystrophy combined with X-linked Charcot-Marie-Tooth neuropathy. 1079 9

Chimeric RNA/DNA oligonucleotides ("chimeraplasts") have been shown to induce single base alterations in genomic DNA both in vitro and in vivo. The mdx mouse strain has a point mutation in the dystrophin gene, the consequence of which is a muscular dystrophy resulting from deficiency of the dystrophin protein in skeletal muscle. To test the feasibility of chimeraplast-mediated gene therapy for muscular dystrophies, we used a chimeraplast (designated "MDX1") designed to correct the point mutation in the dystrophin gene in mdx mice. After direct injection of MDX1 into muscles of mdx mice, immunohistochemical analysis revealed dystrophin-positive fibers clustered around the injection site. Two weeks after single injections into tibialis anterior muscles, the maximum number of dystrophin-positive fibers (approximately 30) in any muscle represented 1-2% of the total number of fibers in that muscle. Ten weeks after single injections, the range of the number of dystrophin-positive fibers was similar to that seen after 2 wk, suggesting that the expression was stable, as would be predicted for a gene-conversion event. Staining with exon-specific antibodies showed that none of these were "revertant fibers." Furthermore, dystrophin from MDX1-injected muscles was full length by immunoblot analysis. No dystrophin was detectable by immunohistochemical or immunoblot analysis after control chimeraplast injections. Finally, reverse transcription-PCR analysis demonstrated the presence of transcripts with the wild-type dystrophin sequence only in mdx muscles injected with MDX1 chimeraplasts. These results provide the foundation for further studies of chimeraplast-mediated gene therapy as a therapeutic approach to muscular dystrophies and other genetic disorders of muscle.
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PMID:Rescue of dystrophin expression in mdx mouse muscle by RNA/DNA oligonucleotides. 1080 97

Duchenne muscular dystrophy (DMD) is an X-linked recessive disease caused by the lack of expression of the dystrophin protein in muscle tissues. We genetically engineered a mouse model (mdx) of DMD that allowed for the high level and inducible transcription of a dystrophin mini-gene. This was achieved via the tetracycline-responsive transactivator (tTA) system. Multiple analyses confirmed that dystrophin expression in the mice was: (i) tTA dependent; (ii) correctly localized to the sarcolemmal membranes; (iii) capable of preventing the onset of dystrophy; and (iv) effectively blocked by the oral administration of tetracyclines. The model allowed us to somatically extinguish or induce dystrophin gene transcription. Somatic induction of dystrophin transcription prevented the onset of muscular dystrophy in some muscle groups. The levels of phenotypic rescue were influenced, however, by the age of the animals at the time of dystrophin induction. We also found that despite somatic termination of dystrophin gene transcription, the dystrophin protein was found to be associated with the sarcolemmal membrane for at least 26 weeks. Persistent detection of dystrophin was also accompanied by a prolonged protection of the muscle cells from the onset of dystrophy. The findings demonstrated that somatic transfer of the dystrophin gene not only may allow for the prevention of muscular dystrophy in multiple muscle groups, but also may be accompanied by persistent efficacy, secondary to the long-term functional stability of the dystrophin protein in vivo. This model should be useful in future studies concerning the potential of genetic therapy for DMD, as well as other muscle disorders.
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PMID:Mdx mice inducibly expressing dystrophin provide insights into the potential of gene therapy for duchenne muscular dystrophy. 1103 Jul 55

Golden retriever muscular dystrophy arises from a mutation in the acceptor splice site of intron 6 of the dystrophin gene. Skipping of exon 7 disrupts the mRNA reading frame and results in premature termination of translation. We are using this animal model to evaluate treatments for Duchenne muscular dystrophy, including gene repair induced by chimeric oligonucleotides. After injection of golden retriever muscular dystrophy (GRMD) muscle with a chimeric oligonucleotide to repair the lesion, immunostaining revealed a modest increase in the number of dystrophin-positive fibres at the injection sites. Dystrophin gene transcripts containing exon 7 were detected by reverse transcription-polymerase chain reaction, suggesting that low levels of splice site correction may have occurred. However, DNA sequencing of these apparently normal dystrophin gene transcripts revealed that the first five bases of exon 7 were missing. It will be important to be aware of this phenomenon with respect to further gene correction studies in the canine model.
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PMID:Cryptic splicing involving the splice site mutation in the canine model of Duchenne muscular dystrophy. 1129 38

Abnormalities of dystrophin are a common cause of muscular dystrophy and testing for dystrophin gene or protein has become a part of routine diagnostic evaluation of patients who present with progressive proximal muscle weakness, high serum creatine kinase concentrations, and histopathological evidence of a dystrophic process. Patients who have no dystrophin abnormalities are assumed to have autosomal recessive muscular dystrophy. In a family consisting of 5 sibs, 2 mentally normal brothers presented with abnormal gait and protrusion of chest and hips. Muscle biopsy from one of them showed dystrophic changes and reduced patchy binding of dystrophin. No detectable deletion was observed in the patient's DNA and his brother with cDMD probes. Dystrophin associated proteins, beta-dystroglycan showed discontinuous immunostaining in the sarcolemma and alpha-sarcoglycan (adhalin) was totally absent, while beta-, gamma-, and delta-sarcoglycans were highly reduced. Immunoblot analysis showed dystrophin of normal molecular weight but of decreased quantity, beta-dystroglycan was reduced by about 37% while alpha-sarcoglycan was completely absent. This study is a first attempt for a systematic clinical, genetic and molecular investigation of the autosomal recessive LGMD in India.
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PMID:Deficiency of the 50 kDa dystrophin-associated-glycoprotein (adhalin) in an Indian autosomal recessive limb girdle muscular dystrophy patient : immunochemical analysis and clinical aspects. 1130 36


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