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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We examined a patient with adult onset sialidosis using N-isopropyl-p-123I-iodoamphetamine single photon emission computed tomography (SPECT) and 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (PET). A 41-year-old [correction of 47] man was admitted to our hospital because of the involuntary movement of his extremities and gait disturbance. On admission, he exhibited action myoclonus in his face and extremities with cerebellar ataxia. Ophthalmoscopy revealed cherry-red spots on his retina. Enzymological analysis of his leucocytes and skin fibroblasts revealed primary sialidase deficit. Brain MRI showed no abnormal findings. Brain SPECT showed decreased cerebral blood flow in the cortex of bilateral occipital lobes, and PET study revealed decreased glucose metabolism in the cortex of bilateral occipital lobes. This case is the thirteenth patient of adult onset sialidosis in Japan. As far as we know, there are no previous reports of SPECT or PET on sialidosis patients. Why the cerebral blood flow and glucose metabolism was decreased in the occipital lobe region remains obscure. From the literatures, we suppose that the onset time of neuronal tissue degeneration or the sensitivity to cumulative metabolites in the occipital region may be different from those in other regions. Further studies are required to confirm abnormalities of cerebral blood flow and metabolism in sialidosis.
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PMID:[Neuroradiological findings on cerebral blood flow and metabolism of a case of adult onset sialidosis]. 950 67

Among the epilepsies, the progressive myoclonus epilepsies (PMEs) form a heterogeneous group of rare diseases characterized by myoclonus, epilepsy, and progressive neurologic deterioration, particularly dementia and ataxia. The success of the Human Genome Project and the fact that most PMEs are inherited through a mendelian or mitochondrial mode have resulted in important advances in the definition of the molecular basis of PME. The gene defects for the most common forms of PME (Unverricht-Lundborg disease, the neuronal ceroid lipofuscinoses, Lafora disease, type I sialidosis, and myoclonus epilepsy with ragged-red fibers) have been either identified or mapped to specific chromosome sites. Unverricht-Lundborg disease has been shown to be caused by mutations in the gene that codes for cystatin B, an inhibitor of cysteine protease. The most common mutation in Unverricht-Lundborg disease is an expansion of a dodecamer repeat located in a noncoding region upstream of the transcription start site of the cystatin B gene, making it the first human disease associated with instability of a dodecamer repeat. Juvenile neuronal ceroid lipofuscinosis is caused by mutations in the CLN3 gene, a gene of unknown function that encodes a 438-amino-acid protein of possible mitochondrial location. Other forms of neuronal ceroid lipofuscinosis that occur as PME and Lafora disease have been mapped by means of linkage analysis, but the corresponding gene defects remain unknown. Sialidosis has been shown to be caused by mutations in the sialidase gene, and myoclonus epilepsy with ragged-red fibers is well known to be caused by mutations in the mitochondrial gene that codes for tRNA(Lys). How the different PME gene defects described produce the various PME phenotypes, including epileptic seizures, remains unknown. The development of animal models that bear these mutations is needed to increase our knowledge of the basic mechanisms involved in the PMEs. This knowledge should lead to the development of new and effective forms of therapy, which are especially lacking for the PMEs.
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PMID:The molecular genetic bases of the progressive myoclonus epilepsies. 1051 28

Progressive myoclonic epilepsies are rare, genetically transmitted diseases characterized by epileptic seizures, myoclonus, and progressive neurologic deterioration. Unverricht-Lundborg disease, Lafora's disease, neuronal ceroid lipofuscinosis, mitochondrial disorders, and sialidosis are included in this group. Lafora's disease is a progressive disorder of the central nervous system with onset in the late first or second decade of life and is inherited in an autosomal-recessive pattern. The first clinical manifestation is generalized tonic-clonic seizures, myoclonus, or both, usually seen between the ages of 11 and 18 years. The other clinical manifestations are progressive dementia and limb ataxia. Diagnosis is based on showing the typical inclusions in the brain, liver, skin, or muscle tissue specimens. The case of a 6-year-old male patient, who was admitted with the clinical findings of third-degree atrioventricular block and dementia and eventually diagnosed with Lafora's disease, is presented.
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PMID:A case of Lafora's disease associated with cardiac arrhythmia. 1059 53

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the hydrolysis of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation and hepatosplenomegaly (sialidosis type II). We have analyzed the genomic DNA from nine sialidosis patients of multiple ethnic origin in order to find mutations responsible for the enzyme deficiency. The activity of the identified variants was studied by transgenic expression. One patient had a frameshift mutation (G623delG deletion), which introduced a stop codon, truncating 113 amino acids. All others had missense mutations: G679G-->A (Gly227Arg), C893C-->T (Ala298Val), G203G-->T (Gly68Val), A544A-->G (Ser182Gly) C808C-->T (Leu270Phe) and G982G-->A (Gly328Ser). We have modeled the three-dimensional structure of sialidase based on the atomic coordinates of the homologous bacterial sialidases, located the positions of mutations and estimated their potential effect. This analysis showed that five mutations are clustered in one region on the surface of the sialidase molecule. These mutations dramatically reduce the enzyme activity and cause a rapid intralysosomal degradation of the expressed protein. We hypothesize that this region may be involved in the interface of sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in their high-molecular-weight complex required for the expression of sialidase activity in the lysosome.
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PMID:Characterization of the sialidase molecular defects in sialidosis patients suggests the structural organization of the lysosomal multienzyme complex. 1076 32

Sialidosis is an autosomal recessive disease caused by the genetic deficiency of lysosomal sialidase, which catalyzes the catabolism of sialoglycoconjugates. The disease is associated with progressive impaired vision, macular cherry-red spots, and myoclonus (sialidosis type I) or with skeletal dysplasia, Hurler-like phenotype, dysostosis multiplex, mental retardation, and hepatosplenomegaly (sialidosis type II). We analyzed the effect of the missense mutations G68V, S182G, G227R, F260Y, L270F, A298V, G328S, and L363P, which are identified in the sialidosis type I and sialidosis type II patients, on the activity, stability, and intracellular distribution of sialidase. We found that three mutations, F260Y, L270F, and A298V, which are clustered in the same region on the surface of the sialidase molecule, dramatically reduced the enzyme activity and caused a rapid intralysosomal degradation of the expressed protein. We suggested that this region might be involved in sialidase binding with lysosomal cathepsin A and/or beta-galactosidase in the multienzyme lysosomal complex required for the expression of sialidase activity. Transgenic expression of mutants followed by density gradient centrifugation of cellular extracts confirmed this hypothesis and showed that sialidase deficiency in some sialidosis patients results from disruption of the lysosomal multienzyme complex.
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PMID:Mutations in sialidosis impair sialidase binding to the lysosomal multienzyme complex. 1127 74

Lysosomal sialidase (EC 3.2.1.18) has a dual physiological function; it participates in intralysosomal catabolism of sialylated glycoconjugates and is involved in cellular immune response. Mutations in the sialidase gene NEU1, located on chromosome 6p21.3, result in autosomal recessive disorder, sialidosis, which is characterized by the progressive lysosomal storage of sialylated glycopeptides and oligosaccharides. Sialidosis type I is a milder, late-onset, normosomatic form of the disorder. Type I patients develop visual defects, myoclonus syndrome, cherry-red macular spots, ataxia, hyperreflexia, and seizures. The severe early-onset form, sialidosis type II, is also associated with dysostosis multiplex, Hurler-like phenotype, mental retardation, and hepatosplenomegaly. We summarize information on the 34 unique mutations determined so far in the sialidase gene, including four novel missense and one novel nonsense mutations found in two Czech and two French sialidosis patients. The analysis of sialidase mutations in sialidosis revealed considerable molecular heterogeneity, reflecting the diversity of clinical phenotypes that make molecular diagnosis difficult. The majority of sialidosis patients have had missense mutations, many of which have been expressed; their effects on activity, stability, intracellular localization, and supramolecular organization of sialidase were studied. A structural model of sialidase allowed us to localize mutations in the sialidase molecule and to predict their impact on the tertiary structure and biochemical properties of the enzyme.
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PMID:Molecular pathology of NEU1 gene in sialidosis. 1451 45

We reported a patient with middle-aged onset sialidosis type I. A 52-year-old Japanese man was referred to our hospital because of dysarthria, involuntary movement of his extremities and gait disturbance since the age of 46 years. On admission, neurological examination revealed scanning speech, action myoclonus, cerebellar ataxia and cherry-red spots. Vacuolated lymphocytes were found in peripheral blood. Brain 18F-2-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) showed decreased glucose metabolism in the cerebellum. Enzymological analysis using his skin fibroblasts revealed primary deficiency of sialidase activity. Sialidase gene analysis identified compound heterozygotes for base substitusions of 239T-to-C and 649G-to-A, which resulted in amino acid alterations of P80L and V217M, respectively. These mutations have been reported in Japanese sialidosis type II (P80L) and I (V217M). Further studies are required to reveal effects of gene mutations on residual enzyme activities and phenotypes.
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PMID:[A case of middle-aged onset sialidosis type I]. 1547 Oct 91

Sialidosis type 1 or the cherry red spot-myoclonus syndrome (CRSM) is an autosomal recessive disorder with the onset in adolescence of myoclonus and gradual visual failure. Here, a case of CRSM in a 12-year-old Bengali Muslim girl with the history of myoclonic jerks of limbs and the body since last 2 years and gradual impairment of vision since last one year is presented with a brief review of the literature.
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PMID:Sialidosis type I (cherry red spot-myoclonus syndrome). 1547 82

Progressive myoclonic epilepsies (PMEs) are a group of rare disorders characterized by the occurrence of seizures, myoclonus, and progressive neurological dysfunction. This article discusses epidemiology, genetics, pathology, clinical manifestations, EEG characteristics, methods of diagnosis and treatment of the most common causes of PME, including Unverricht-Lundborg Disease (Baltic Myoclonus), MERRF, neuronal ceroid lipofuscinosis, dentatorubropallidoluysan atrophy, Gaucher disease, Lafora disease, and sialidosis. The aim of this paper is to provide clinicians with useful clinical information in order to facilitate the diagnosis and treatment of these rare diseases.
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PMID:Progressive myoclonic epilepsy. 1554 6

Autosomal recessively inherited progressive myoclonus epilepsies (PMEs) include Lafora disease, Unverricht-Lundborg disease, the neuronal ceroid lipofuscinoses, type I sialidosis (cherry-red spot myoclonus), action myoclonus-renal failure syndrome, and type III Gaucher disease. Almost all the autosomal recessively inherited PMEs are lysosomal diseases, with the exception of Lafora disease in which neither the accumulating material nor the gene products are in lysosomes. Progress in identifying the causative defects of PME is near-complete. Much work lies ahead to resolve the pathobiology and neurophysiology of this group of devastating disorders.
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PMID:The autosomal recessively inherited progressive myoclonus epilepsies and their genes. 1946 43


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