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

Congenital muscular dystrophy is one of the most frequent and severe childhood muscular dystrophies. Several forms of this disease have been described. The form associated with marked central nervous system disturbances, frequent in Japan, is known as Fukuyama congenital muscular dystrophy and was recently linked to chromosome 9. The most frequent form observed in occidental countries appears to be clinically characterized by exclusive involvement of skeletal muscle, and has been identified by clinico-pathological features which are often fallacious. A predominant histopathological feature is the marked increase in endomysial collagen tissue. We investigate whether laminin, a major component of the extracellular matrix, which is linked to the subsarcolemmal cytoskeleton by a large oligomeric complex of dystrophin-associated glycoproteins, could be involved in this form. We observed a specific absence of merosin, the laminin M chain, in 13 patients affected by classical non-Japanese form of congenital muscular dystrophy. This result allows the precise identification of a particular form of congenital muscular dystrophy and gives a clue to understanding its molecular pathogenesis.
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PMID:Congenital muscular dystrophy with merosin deficiency. 800 Sep 14

Merosin is the predominant laminin isoform in the basal lamina of striated muscle and peripheral nerve, and consists of M, B1 or S, and B2 chains. Here we have demonstrated that merosin is a native ligand for alpha-dystroglycan, an extracellular component of the dystrophin-glycoprotein complex. We have also mapped the mouse M chain gene, Lamm, to the same region of mouse chromosome 10 to which the dystrophia muscularis (dy) locus has been mapped. The dy mutation represents a severe neuromuscular disease resembling human muscular dystrophy. Analysis of merosin expression of dystrophic dy mice revealed a specific deficiency of merosin in skeletal muscle, cardiac muscle, and peripheral nerve. Our results indicate that merosin deficiency may be the primary defect in dy mice and suggest that a disruption of the link between alpha-dystroglycan and merosin may be involved in the pathogenesis of muscle degeneration and peripheral neuropathy in dy mice.
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PMID:Deficiency of merosin in dystrophic dy mice and genetic linkage of laminin M chain gene to dy locus. 818 45

To address potential involvement of muscle basal lamina and membrane cytoskeleton proteins in the etiology of non-dystrophinopathy muscular dystrophies, we examined the immunostaining intensity and distribution of laminin subunits (A, B1, B2 and M), type IV collagen, dystrophin and spectrin in skeletal muscle biopsies from 64 myopathic patients (17 Fukuyama congenital muscular dystrophy: FCMD, 13 congenital muscular dystrophy unrelated to FCMD: other CMD, 16 Duchenne muscular dystrophy: DMD, and 18 other neuromuscular diseases. In FCMD muscle, we found a significant reduction of laminin M (merosin; a striated muscle specific basal lamina-associated protein) with approximately 26% of levels seen in controls by quantitative immunofluorescence. Other CMD and DMD muscles showed less dramatic reductions (78%, 80%, respectively). The localization of laminin M was also abnormal in FCMD muscle. Laminin B1 and B2 showed abnormalities similar to those observed with laminin M, but were less marked. Laminin A was only detected in rare regenerating fibers in control biopsies, whereas it was seen around most muscle fibers in FCMD patients, and in dystrophin deficient muscle fibers from DMD patients and its carrier. Staining intensity of type IV collagen in FCMD muscle was not significantly different from the other diseases. These findings may implicate a primary or central role for the basal lamina in FCMD muscle.
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PMID:Abnormal localization of laminin subunits in muscular dystrophies. 824 11

The absence of laminin alpha 2 chain causes muscle cell degeneration and peripheral dysmyelination in congenital muscular dystrophy patients and dy mice, suggesting its role in the maintenance of sarcolemmal architecture and peripheral myelinogenesis. Here we demonstrate the secretion of laminin alpha 2 chain in cerebrospinal fluid (CSF). Laminin alpha 2 chain was detected as a minor component of the total CSF proteins or glycoproteins. Laminin alpha 2 chain was localized in the cytoplasm of epithelial cells of choroid plexus, suggesting active secretion. Our results suggest that immunochemical analysis of CSF laminin alpha 2 chain could be useful as an aid for the diagnosis of congenital muscular dystrophy.
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PMID:Secretion of laminin alpha 2 chain in cerebrospinal fluid. 852 61

Considerable advances in the understanding of congenital muscular dystrophy made during the past year may allow a new clinical classification of this disease. In particular, (1) evidence has accumulated to suggest that a laminin alpha2-chain (alpha2 subunit of laminin-2 or merosin) deficiency causes a type of congenital muscular dystrophy, and (2) it has been postulated that Fukuyama-type congenital muscular dystrophy and Walker-Warburg syndrome (but not Finnish muscle-eye-brain disease) are genetically identical diseases.
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PMID:Congenital muscular dystrophies. 854 45

It has recently been shown that merosin, a laminin variant, is deficient in a proportion of patients with congenital muscular dystrophy. Merosin is a heterotrimer composed of the alpha 2, beta 1, and gamma 1 subunits, and further studies have shown that it is the alpha 2 subunit that is deficient in these patients. Because the alpha 2 subunit is also expressed in S-merosin, found in Schwann cells, we have investigated whether peripheral nerve function is also affected in these patients. Motor nerve conduction velocities and sensory distal latencies were examined in 25 cases of congenital muscular dystrophy and the results correlated with the merosin expression in their muscle biopsies. All but two of the 10 merosin-deficient cases had reduced motor nerve conduction, whereas all the merosin-positive cases had normal results. Analysis of the biopsies of these two cases showed that they produced merosin in reduced amounts, in contrast to all other merosin-deficient patients that produced no or only traces of merosin. Sensory nerve studies showed no difference between the two groups. These results indicate that a peripheral demyelinating neuropathy is a feature of merosin-deficient congenital muscular dystrophy. The fact that the alpha 2 subunits is also expressed in Schwann cells supports the idea that the alpha 2 gene, located on chromosome 6, is the candidate gene for merosin-deficient congenital muscular dystrophy.
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PMID:Demyelinating peripheral neuropathy in merosin-deficient congenital muscular dystrophy. 857 59

Congenital muscular dystrophy syndromes are characterized by congenital weakness, contractures, and dystrophic features on muscle biopsy. However, these syndromes are often difficult to diagnose precisely because their clinical and pathologic characteristics are not specific and resemble changes in other myopathies. We examined muscle biopsies from 20 children with a congenital muscular dystrophy syndrome. Disease controls with dystrophies or other myopathies (n=19) and normal individuals (n=15) were studied for comparison. In each biopsy we determined (1) numbers of muscle fibers with alkaline phosphatase (AlkP) staining, (2) numbers of acid phosphatase-(AcP) positive cells, (3) dystrophin levels by immunocytochemistry, and (4) the distribution of merosin and laminin-A staining. A ratio of AcP:AlkP staining was calculated for each biopsy. In nine patients with congenital muscular dystrophy (younger than 4 years of age) with normal dystrophin, the AcP:AlkP ratio was low (0.09 +/- 0.03). In contrast, in Duchenne muscular dystrophy, the AcP:AlkP ratio was 15 times higher (1.6 +/- 0.04, p=0.001). The three children with congetial muscular dystrophy syndromes and reduced dystrophin and one child with facioscapulohumeral dystrophy had AcP:AlkP ratios in the range of Duchenne muscular dystrophy patients (2.4 +/- 1.4). Low Ac:AlkP ratios were related to relative absence of AcP-positive cells. Merosin staining was absent in 5 of the 17 congenital muscular dystrophy biopsies tested. None of the 5 children with merosin-negative but all 12 with merosin-positive stains walked (p=0.0002). We conclude that a pattern of few AcP-positive cells in the setting of numerous AlkP staining muscle fibers has specificity for congenital muscular dystrophy syndromes and provides histopathologic support for the diagnosis. Reduced merosin in muscle predicts more severe weakness and long-term disability.
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PMID:Congenital muscular dystrophy syndromes distinguished by alkaline and acid phosphatase, merosin, and dystrophin staining. 861 88

We studied 50 patients with the merosin-positive form of congenital muscular dystrophy (MP-CMD) clinically and pathologically. The frequency of MP-CMD in our laboratory was approximately one-half that of the Fukuyama type and one-sixth that of Duchenne muscular dystrophy. The early signs of MP-CMD included decreased fetal movement during pregnancy (14%) and poor suck (42%), floppiness (30%), and respiratory difficulty (16%) in early infancy. Eighty-six percent of the patients had delayed motor development. Ninety-two percent of the patients followed beyond age 4 years had learned to walk. The disease was relatively slowly progressive, except in six patients who rapidly lost ambulation. Almost all patients had normal IQ, except four who were mildly to moderately retarded. Of the patients examined by cranial CT/MRI, 24% showed cerebral atrophy and 11% had areas of white matter lucency. Muscle biopsy results in those younger than 5 years showed mild dystrophic changes consisting of variation in fiber size and scattered necrotic and regenerating fibers. In older children, there were additional chronic dystrophic changes, including fiber splitting (32%), moth-eaten appearance (32%), marked fatty replacement (46%), and abnormal fiber type distribution (59%). The manifestations of MP-CMD were generally milder and more slowly progressive than those of the Fukuyama type and merosin-negative form of congenital muscular dystrophy.
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PMID:Congenital muscular dystrophy: Clinical and pathologic study of 50 patients with the classical (Occidental) merosin-positive form. 861 89

Dystoroglycan is encoded by a single gene and cleaved into two proteins, alpha and beta-dystroglycan, by posttranslational processing. The 120kDa peripheral nerve isoform of alpha-dystroglycan binds laminin-2 comprised of the alpha 2, beta 1, and gamma 1 chains. In congenital muscular dystrophy and dy mice deficient in laminin alpha 2 chain, peripheral myelination is disturbed, suggesting a role for the dystroglycan- laminin interaction in peripheral myelinogenesis. To begin to test this hypothesis, we have characterized the dystroglycan-laminin interaction in peripheral nerve. We demonstrate that (1) alpha-dystroglycan is an extracellular peripheral membrane glycoprotein that links beta-dystroglycan in the Schwann cell outer membrane with laminin-2 in the endoneurial basal lamina, and (2) dystrophin homologues Dp116 and utrophin are cytoskeletal proteins of the Schwann cell cytoplasm. We also present data that suggest a role for glycosylation of alpha-dystroglycan in the interaction with laminin.
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PMID:Characterization of dp6troglycan-laminin interaction in peripheral nerve. 862 7

Recently, a deficiency of merosin has been reported in patients with classical congenital muscular dystrophy (CMD), while other patients, with indistinguishable clinico-pathological features, do not present this deficiency, suggesting genetic heterogeneity. The purpose of the present investigation was to assess merosin distribution and quantity in 21 clinically well characterized Brazilian CMD patients, in order to: a) estimate the proportion of merosin-deficient cases in this group of patients; b) characterize phenotypically merosin-negative, as compared to merosin-positive patients. Merosin deficiency was found in 11 patients and all the seven who had been submitted to neuroimaging studies showed evidence of periventricular dysmyelination. A normal pattern of 43 DAG was found in all patients, which suggest that this protein is not preferentially involved in a third form of merosin-positive CMD. Results from the present study are further suggestive, but do not prove, that the association of merosin deficiency with white matter alterations represents a genetic entity with common clinical, laboratory and neuroimaging findings.
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PMID:Deficiency of merosin (laminin M or alpha 2) in congenital muscular dystrophy associated with cerebral white matter alterations. 871 43


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