Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A case of an unusual congenital myopathy is reported. The boy presented at birth with generalized muscular hypotonia and dysmorphic features. Muscle biopsy at the age of 10 years revealed focal areas with decreased ATPase activity and variable oxidative enzyme activity. There was only one type II fiber in the whole section. 22.5% of fibers had central nuclei, sometimes with radial arrangement of the intermyofibrillary network. Focal lesions displayed strong desmin and weak vimentin immunoreactivity. On electron microscopic examination normal sarcomeres were focally disrupted and mitochondria were absent from these areas; the normal structure was replaced by numerous fragments of sarcoplasmic reticulum, filamentous material, scattered glycogen particles, and the Z-line was replaced by irregular longitudinal streaks of electron-dense fibrillar material. We classify this case as a congenital myopathy with focal loss of cross striations.
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PMID:Congenital myopathy with focal loss of cross striations: a case report with morphologic and immunohistochemical study. 854 96

We report a second child with broad A band disease. This child differs from the first in having normal vision and no electrophysiological evidence of a congenital retinal dystrophy. Neurological abnormalities at presentation included diffuse hypotonia, developmental delay, and delayed speech development. Histological and preliminary histochemical evaluation of biopsied thigh muscle showed no abnormality. However, 1-micrometer-thick plastic sections and electron microscopy showed numerous foci of broadened A bands accompanied by loss of distinct I bands. The Z lines in these areas were normal except for a fine waviness. Ultrastructurally, the thick filaments in these lesions appeared misaligned. Immunohistochemical reactions for desmin, vimentin, connectin (titin), and 2B myosin showed normal reactivity. An immunohistochemical reaction for fetal myosin showed sparse reacting fibers, which were unremarkable on adjacent sections stained with hematoxylin and eosin. These findings differ from those of other previously described congenital myopathies. Both of our patients have shown good strength and motor development by 5 years of age, suggesting that this ultrastructural abnormality is essentially benign.
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PMID:Broad A band disease: a new benign congenital myopathy. 861 56

Myotubular myopathy frequently presents in male infants with severe generalised muscular hypotonia and weakness associated with ventilatory insufficiency, and is diagnosed on biopsy by the presence of many fibres with central nuclei and mitochondrial aggregation. In a 6-year period, we have investigated five unrelated patients with clinical and pathological features suggesting an X-linked myotubular myopathy, including one female patient. In one male infant, a biopsy of vastus lateralis showed less than 2% centrally-nucleated fibres, while biceps brachii showed up to 15% centrally-nucleated fibres. Immunohistochemical expression of the neural cell adhesion molecule (CD56) was more intense in the biceps muscle than in vastus lateralis, while expression of desmin and vimentin was similar. Morphometric evaluation of tissue from each of the patients revealed a wide spread of values for the number of centrally-nucleated fibres per microscopic field, and variation in the extent of immunohistochemical expression of NCAM, utrophin, laminin alpha 5 chain, vimentin and HLA1 antigen. These variations in the manifestations of myotubular myopathy have not been previously described, and will need to be correlated with the increasing knowledge of the mutations in the MTM1 gene coding for myotubularin.
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PMID:Myotubular myopathy: morphological, immunohistochemical and clinical variation. 963 95

Four unrelated patients are reported with muscle hypotonia, weakness, skeletal dysmorphism and respiratory insufficiency since childhood. Muscle tissues were found to contain a number of muscle fibres with abnormal structure. Peripherally located structures such as a cap lacking in ATP-ase and fast myosin activity, rich in desmin, tropomyosin and alpha-actinin consisted of abnormally arranged myofibrils. The position of the peripherally situated myofibrils, as well as their abnormal sarcomere pattern, seems to point to an error in fusion and muscle protein synthesis. Whether our cases of congenital myopathy with cap structures are of hereditary origin or of a sporadic type remains unknown, so far. It seems that the result of our study, as well as data presented in the literature, allows us to divede cap disease into two forms: fatal and nonfatal. The morphological changes in the muscle fibres are identical in all the presented cases but the number of muscle fibres with cap structures is much higher in the fatal form.
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PMID:"Cap disease"--a failure in the correct muscle fibre formation. 1216 90

Central core disease is a nonprogressive or slowly progressive congenital myopathy with a variable degree of hypotonia and axial and proximal muscle weakness that is histologically characterized by areas devoid of oxidative enzyme activity, resulting from an absence or low numbers of mitochondria in these regions (central core). A 10-month-old, male, pony foal was examined because of stiff gait, marked contractures of the distal portion of the limbs, flexion deformities of the hooves, and moderate hypotonia that had been present from birth. The foal had increased creatine kinase (282 U/liter; reference interval 10-135 U/liter), lactate dehydrogenase (1,188 U/liter; reference interval 150-450 U/liter), and aspartate transaminase (377 U/liter; reference interval <290 U/liter) activities, suggesting muscle disease. Muscle biopsy was performed. In cytochrome oxidase-, succinate dehydrogenase-, and reduced nicotinamide adenine dinucleotide tetrazolium reductase-reacted sections, the dominant morphologic feature was the absence of oxidative enzyme activity in the cores. By use of immunohistochemical technique with a monoclonal antibody against desmin, the cores were clearly delineated and a desmin network was present within the cores. Ultrastructurally, the core areas were characterized by preserved sarcomeres with irregular Z-lines, with some streaming or zigzag appearance and abnormal sarcoplasmic reticulum profiles and T-tubules. Lack of mitochrondria within central cores was observed. Diagnosis of myopathy with central cores was made.
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PMID:Myopathy with central cores in a foal. 1684 6

The selenoprotein N1-related myopathies comprise rigid spine muscular dystrophy, the "classical" form of multiminicore disease, a desmin-related myopathy with Mallory body like inclusions and a form of congenital fiber-type disproportion. To define the phenotype and long-term clinical course in juvenile Selenoprotein N1-related myopathies 11 juvenile patients from eight families with SEPN1 mutations were assessed over a mean period of 7.2 years. Clinical findings, histomorphological studies, respiratory investigations and genetic data were analyzed: age of manifestation varied within the first 2 years of life with muscle hypotonia, lag of head control and delayed motor development. Further gross motor development was normal in 9/11 patients. All patients were ambulant for at least 1000 m at a mean age of 13.7 years. Eight patients exhibited a rigid spine diagnosed at a mean age of 10 years. All patients had respiratory impairment with a vital capacity ranging from 18% to 65%. Four patients were intermittently nocturnally ventilated at a mean age of 11 years. Body mass index was below 20 (kgm(-2)) in all patients. Muscle biopsies of eight individuals revealed multiminicores (n=2), congenital fiber-type disproportion (n=1), myopathic changes with single cores (n=2) and unspecific myopathic features (n=3). Mutations were distributed throughout the entire SEPN1 gene. Although the phenotype of juvenile selenoprotein N1-related myopathies is homogenous regarding the main symptoms we describe a variable degree of clinical severity. Major complications were early respiratory failure, impaired increase in weight and orthopedic problems. There seems to be no correlation between skeletal muscle weakness and respiratory failure.
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PMID:The phenotype and long-term follow-up in 11 patients with juvenile selenoprotein N1-related myopathy. 1795 Oct 86

Nemaline myopathy (NM) is a congenital disease that leads to hypotonia and feeding difficulties in neonates. Some cases have a more benign course, with skeletal abnormalities later in life. We analyzed a series of eight patients with NM obtained from a retrospective analysis of 4300 muscle biopsies. Patients were classified as having the typical form in five cases, intermediate form in two cases and severe form in one case. Histochemical analysis showed mixed rods distribution in all cases and predominance of type I fibers in five cases. Immunohistochemical analysis showed abnormal nebulin expression in all patients (four heterogeneous and four absent), homogeneous desmin expression in four cases, strongly positive in three and absent in one, fast myosin expression in a mosaic pattern in six cases and absent in two cases. There was no specific relation between these protein expression patterns and the clinical forms of NM.
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PMID:Nemaline myopathy: clinical, histochemical and immunohistochemical features. 1983 23

Congenital myopathies (CMs), a group of relatively non-progressive disorders presents with weakness and hypotonia of varying severity, morphologically recognized by specific structural abnormalities within the myofiber. This report presents the clinical and Histopathological features of 40 patients with CMs. Centronuclear myopathy was the commonest (40%) followed by congenital fiber type disproportion (37.5%). Other less common CMs included: myotubular myopathy (5%), nemaline myopathy (5%), central core disease (5%), multicore disease (2.5%) and congenital myopathy with tubular aggregate (5%). Immunolabeling to desmin corresponded to morphological changes within the myofibers while vimentin was negative in all the patients. There is no combined role of these proteins in the disease process.
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PMID:Congenital myopathies: clinical and immunohistochemical study. 2223 3

Myotubular myopathy (MIM#310400), the X-linked form of Centronuclear myopathy (CNM) is mainly characterized by neonatal hypotonia and inability to maintain unassisted respiration. The MTM1 gene, responsible for this disease, encodes myotubularin - a lipidic phosphatase involved in vesicle trafficking regulation and maturation. Recently, it was shown that myotubularin interacts with desmin, being a major regulator of intermediate filaments. We report the development of a locus-specific database for MTM1 using the Leiden Open Variation database software (http://www.lovd.nl/MTM1), with data collated for 474 mutations identified in 472 patients (by June 2012). Among the entries are a total of 25 new mutations, including a large deletion encompassing introns 2-15. During database implementation it was noticed that no large duplications had been reported. We tested a group of eight uncharacterized CNM patients for this specific type of mutation, by multiple ligation-dependent probe amplification (MLPA) analysis. A large duplication spanning exons 1-5 was identified in a boy with a mild phenotype, with results pointing toward possible somatic mosaicism. Further characterization revealed that this duplication causes an in-frame deletion at the mRNA level (r.343_444del). Results obtained with a next generation sequencing approach suggested that the duplication extends into the neighboring MAMLD1 gene and subsequent cDNA analysis detected the presence of a MTM1/MAMLD1 fusion transcript. A complex rearrangement involving the duplication of exon 10 has since been reported, with detection also enabled by MLPA analysis. It is thus conceivable that large duplications in MTM1 may account for a number of CNM cases that have remained genetically unresolved.
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PMID:Expanding the MTM1 mutational spectrum: novel variants including the first multi-exonic duplication and development of a locus-specific database. 2296 36

Joubert syndrome (JBTS) is a predominantly autosomal recessive neurodevelopmental disorder that presents with characteristic malformations of the cerebellar vermis, superior cerebellar peduncles and midbrain in humans. Accompanying these malformations are a heterogeneous set of clinical symptoms, which frequently include deficits in motor and muscle function, such as hypotonia (low muscle tone) and ataxia (clumsiness). These symptoms are attributed to improper development of the hindbrain, but no direct evidence has been reported linking these in JBTS. Here, we describe muscle developmental defects in a mouse with a targeted deletion of the Abelson helper integration site 1 gene, Ahi1, one of the genes known to cause JBTS in humans. While FVB/NJ Ahi1-/- mice display no gross malformations of the cerebellum, deficits are observed in several measures of motor function, strength, and body development. Specifically, Ahi1-/- mice show delayed physical development, delays in surface reflex righting as neonates, and reductions in grip strength and spontaneous locomotor activity as adults. Additionally, Ahi1-/- mice showed evidence of muscle-specific contributions to this phenotype, such as reductions in 1) myoblast differentiation potential in vitro, 2) muscle desmin expression, and 3) overall muscle mass, myonuclear domain, and muscle fiber cross-sectional area. Together, these data suggest that loss of Ahi1 may cause abnormalities in the differentiation of myoblasts to mature muscle cells. Moreover, Ahi1 loss impacts muscle development directly, outside of any indirect impact of cerebellar malformations, revealing a novel myogenic cause for hypotonia in JBTS.
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PMID:Loss of the neurodevelopmental Joubert syndrome causing protein, Ahi1, causes motor and muscle development delays independent of central nervous system involvement. 3069 85


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