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

Miyoshi myopathy (MM) is an adult onset, recessive inherited distal muscular dystrophy that we have mapped to human chromosome 2p13. We recently constructed a 3-Mb P1-derived artificial chromosome (PAC) contig spanning the MM candidate region. This clarified the order of genetic markers across the MM locus, provided five new polymorphic markers within it and narrowed the locus to approximately 2 Mb. Five skeletal muscle expressed sequence tags (ESTs) map in this region. We report that one of these is located in a novel, full-length 6.9-kb muscle cDNA, and we designate the corresponding protein 'dysferlin'. We describe nine mutations in the dysferlin gene in nine families; five are predicted to prevent dysferlin expression. Identical mutations in the dysferlin gene can produce more than one myopathy phenotype (MM, limb girdle dystrophy, distal myopathy with anterior tibial onset).
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PMID:Dysferlin, a novel skeletal muscle gene, is mutated in Miyoshi myopathy and limb girdle muscular dystrophy. 973 26

The limb-girdle muscular dystrophies are a genetically heterogeneous group of inherited progressive muscle disorders that affect mainly the proximal musculature, with evidence for at least three autosomal dominant and eight autosomal recessive loci. The latter mostly involve mutations in genes encoding components of the dystrophin-associated complex; another form is caused by mutations in the gene for the muscle-specific protease calpain 3. Using a positional cloning approach, we have identified the gene for a form of limb-girdle muscular dystrophy that we previously mapped to chromosome 2p13 (LGMD2B). This gene shows no homology to any known mammalian gene, but its predicted product is related to the C. elegans spermatogenesis factor fer-1. We have identified two homozygous frameshift mutations in this gene, resulting in muscular dystrophy of either proximal or distal onset in nine families. The proposed name 'dysferlin' combines the role of the gene in producing muscular dystrophy with its C. elegans homology.
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PMID:A gene related to Caenorhabditis elegans spermatogenesis factor fer-1 is mutated in limb-girdle muscular dystrophy type 2B. 973 27

Recently, a single gene, DYSF, has been identified which is mutated in patients with limb-girdle muscular dystrophy type 2B (LGMD2B) and with Miyoshi myopathy (MM). This is of interest because these diseases have been considered as two distinct clinical conditions since different muscle groups are the initial targets. Dysferlin, the protein product of the gene, is a novel molecule without homology to any known mammalian protein. We have now raised a monoclonal antibody to dysferlin and report on the expression of this new protein: immunolabelling with the antibody (designated NCL-hamlet) demonstrated a polypeptide of approximately 230 kDa on western blots of skeletal muscle, with localization to the muscle fibre membrane by microscopy at both the light and electron microscopic level. A specific loss of dysferlin labelling was observed in patients with mutations in the LGMD2B/MM gene. Furthermore, patients with two different frameshifting mutations demonstrated very low levels of immunoreactive protein in a manner reminiscent of the dystrophin expressed in many Duchenne patients. Analysis of human fetal tissue showed that dysferlin was expressed at the earliest stages of development examined, at Carnegie stage 15 or 16 (embryonic age 5-6 weeks). Dysferlin is present, therefore, at a time when the limbs start to show regional differentiation. Lack of dysferlin at this critical time may contribute to the pattern of muscle involvement that develops later, with the onset of a muscular dystrophy primarily affecting proximal or distal muscles.
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PMID:Dysferlin is a plasma membrane protein and is expressed early in human development. 1019 75

Limb girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM), a distal muscular dystrophy, are both caused by mutations in the recently cloned gene dysferlin, gene symbol DYSF. Two large pedigrees have been described which have both types of patient in the same families. Moreover, in both pedigrees LGMD2B and MM patients are homozygous for haplotypes of the critical region. This suggested that the same mutation in the same gene would lead to both LGMD2B or MM in these families and that additional factors were needed to explain the development of the different clinical phenotypes. In the present paper we show that in one of these families Pro791 of dysferlin is changed to an Arg residue. Both the LGMD2B and MM patients in this kindred are homozygous for this mutation, as are four additional patients from two previously unpublished families. Haplotype analyses suggest a common origin of the mutation in all the patients. On western blots of muscle, LGMD2B and MM patients show a similar abundance in dysferlin staining of 15 and 11%, respectively. Normal tissue sections show that dysferlin localizes to the sarcolemma while tissue sections from MM and LGMD patients show minimal staining which is indistinguishable between the two types. These findings emphasize the role for the dysferlin gene as being responsible for both LGMD2B and MM, but that the distinction between these two clinical phenotypes requires the identification of additional factor(s), such as modifier gene(s).
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PMID:Identical mutation in patients with limb girdle muscular dystrophy type 2B or Miyoshi myopathy suggests a role for modifier gene(s). 1019 77

A multiplex system of Western blotting is presented in which most of the current muscular dystrophy proteins can be analyzed simultaneously on one pair of blots. This represents a significant improvement in efficiency and cost for this type of analysis. The final diagnosis is more quickly achieved in patients where several possible diagnoses are indicated after clinical appraisal, and those with unusual presentations may be quickly resolved. The method uses a biphasic polyacrylamide gel system, which enables the corresponding blot to be probed simultaneously with a cocktail of monoclonal antibodies. The gel is optimized so that large proteins of more than 200 kd (eg, dystrophin, dysferlin, and myosin heavy chain) can be analyzed in the top part, while smaller proteins under 150 kd (eg, calpain 3, the 80-kd fragment of laminin alpha2 chain, all of the sarcoglycans, and caveolin 3) are separated in the lower phase. This basic system could be used for different combinations of antibodies as new muscular dystrophy proteins are identified and require examination. In addition, analysis of the laminin alpha2 chain of merosin showed that this protein was expressed as a doublet or triplet set of bands in many patients with active muscle pathology. This may indicate the existence of an embryonic isoform, which is re-expressed in regenerating fibers.
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PMID:Multiplex Western blotting system for the analysis of muscular dystrophy proteins. 1023 40

Dysferlin, the gene product of the limb girdle muscular dystrophy (LGMD) 2B locus, encodes a membrane-associated protein with homology to Caenorhabditis elegans fer-1. Humans with mutations in dysferlin ( DYSF ) develop muscle weakness that affects both proximal and distal muscles. Strikingly, the phenotype in LGMD 2B patients is highly variable, but the type of mutation in DYSF cannot explain this phenotypic variability. Through electronic database searching, we identified a protein highly homologous to dysferlin that we have named myoferlin. Myoferlin mRNA was highly expressed in cardiac muscle and to a lesser degree in skeletal muscle. However, antibodies raised to myoferlin showed abundant expression of myoferlin in both cardiac and skeletal muscle. Within the cell, myoferlin was associated with the plasma membrane but, unlike dysferlin, myoferlin was also associated with the nuclear membrane. Ferlin family members contain C2 domains, and these domains play a role in calcium-mediated membrane fusion events. To investigate this, we studied the expression of myoferlin in the mdx mouse, which lacks dystrophin and whose muscles undergo repeated rounds of degeneration and regeneration. We found upregulation of myoferlin at the membrane in mdx skeletal muscle. Thus, myoferlin ( MYOF ) is a candidate gene for muscular dystrophy and cardiomyopathy, or possibly a modifier of the muscular dystrophy phenotype.
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PMID:Myoferlin, a candidate gene and potential modifier of muscular dystrophy. 1060 32

New discoveries have dramatically changed the way we approach and think about patients with childhood muscular dystrophies. An aura of order and organization seems to be at hand for a group of diseases which previously seemed endlessly heterogeneous. We have learned that young boys and girls with proximal muscle weakness, large calves and elevated serum CK may have any one of a number of closely connected disorders which affect a complex of interacting proteins of the dystrophin-glycoprotein complex. This complex links the intracellular cytoskeleton to the extracellular matrix. Patients with Duchenne and Becker dystrophies lack dystrophin, while some of the limb girdle muscular dystrophies (an archaic term) are deficient in sarcoglycans and other proteins. The concept of interrelated disorders extends to the previously orphaned distal muscular dystrophies, or distal myopathies, as they are often called. A surprise finding is that the C. elegans protein, dysferlin, is conserved and expressed in man. We know little of the function of this protein in human primates, but its loss in muscle has brought seemingly disparate disorders together, since both a form of LGMD (2B) and distal myopathy (Miyoshi myopathy) are deficient in this same gene product. The congenital muscular dystrophies are also well-entrenched in our expanding concepts of orderliness of disease. The defect in the laminin-alpha2 chain, a direct ligand to the dystrophin-glycoprotein complex, causes a form of muscular dystrophy which affects infants. Another variant of congenital muscular dystrophy is deficient the integrin alpha7, an important laminin receptor. Finally, in Fukuyama congenital muscular dystrophy, the deficient fukutin gene product may also be linked to the basal lamina, permitting overmigration of neuronal cells which lead to micropolygyria in the brain, and at the same time cause basal lamina defects in the extracellular matrix of skeletal muscle, which leads to muscular dystrophy. As we approach the millennium, those of us who have seen the transition from the pre-molecular to the molecular era of myology know that we leave behind a great legacy of chaos (no great loss), replaced by a foundation for conceptual organization which will serve to establish new roots for research as well as for the enriched practice of medicine. The future looks bright for our field and our patients!
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PMID:The childhood muscular dystrophies: making order out of chaos. 1071 85

Miyoshi myopathy (MM) is autosomal recessive distal muscular dystrophy that we have mapped to chromosome 2 p13. We constructed a 3 Mb P 1-derived artificial chromosome contig spanning the MM candidate region. Using this and new polymorphic markers within it, we recently identified a novel, full-length 6.9 kb muscle cDNA, whose corresponding protein we designated "dysferlin" (Nature Genet, 1998: 20: 31-36). We described eighteen mutations in the dysferlin gene with MM or limb-girdle muscular dystrophy type 2 B (LGMD 2 B). Most are predicted to block translation of dysferlin protein. In some cases, corresponding Western immunoblotting reveals absence of dysferlin in muscle biopsies. Identical mutations in the dysferlin gene can produce more than one myopathy phenotype (MM, limb-girdle dystrophy, distal myopathy with anterior tibial onset).
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PMID:[Positional cloning of the gene for Miyoshi myopathy and limb-girdle muscular dystrophy]. 1079 Oct 95

Dysferlin, the protein product of the gene mutated in patients with an autosomal recessive limb-girdle muscular dystrophy type 2B (LGMD2B) and a distal muscular dystrophy, Miyoshi myopathy, is homologous to a Caenorhabditis elegans spermatogenesis factor, FER-1. Analysis of fer-1 mutants and of sequence predictions of the FER-1 and dysferlin ORFs has predicted a role in membrane fusion. Otoferlin, another human FER-1-like protein (ferlin), has recently been shown to be responsible for autosomal recessive nonsyndromic deafness (DFNB9). In this report we describe the third human ferlin gene, FER1L3, which maps to chromosome 10q23.3. Expression analysis of the orthologous mouse gene shows ubiquitous expression but predominant expression in the eye, esophagus, and salivary gland. All the ferlins are characterized by sequences corresponding to multiple C2 domains that share the highest level of homology with the C2A domain of rat synaptotagmin III. They are predicted to be Type II transmembrane proteins, with the majority of the protein facing the cytoplasm anchored by the C-terminal transmembrane domain. Sequence and predicted structural comparisons have highlighted the high degree of similarity of dysferlin and FER1L3, which have sequences corresponding to six C2 domains and which share more than 60% amino acid sequence identity.
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PMID:The third human FER-1-like protein is highly similar to dysferlin. 1099 73

This lecture traces recent advances in knowledge of the muscular dystrophies, as well as their increasing complexity. They are described through the eyes of the author from his first exposure to and complete ignorance of the disease in the late 1950s, through the advent of modern techniques, to the molecular genetic revolution, with the recognition of individual genes and proteins for disorders within the muscular dystrophy umbrella. There initially seemed to be a logical sequence of linked membrane proteins from dystrophin in Duchenne and Becker dystrophy, through the dystrophin-associated glycoproteins (sarcoglycans) in some of the limb girdle muscular dystrophies (LGMD), to the extracellular matrix protein merosin (alpha-2 laminin) in congenital muscular dystrophy (CMD). The first spoke in the wheel came with the discovery of a calcium activated protease enzyme, calpain 3, in one form of LGMD, and subsequently another novel non-membrane protein, dysferlin, in another. There are currently at least eight distinct genetic forms of LGMD alone, and another eight separate genetic entities in the CMD group. This has highlighted our ignorance of the pathogenesis of the muscular dystrophies in relation to a diverse array of protein deficiencies. To compound things further, the X-linked and dominant forms of Emery-Dreifuss muscular dystrophy have recently been linked to emerin and lamin A/C, respectively, two proteins of the nuclear membrane, opening up yet another new ballpark of discovery.
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PMID:What is muscular dystrophy? Forty years of progressive ignorance. 1107 61


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