Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0013421 (dystonia)
 8,418 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deletion of a single glutamate in torsinA correlates with early-onset dystonia, the most severe form of a neurological disorder characterized by uncontrollable muscle contractions. TorsinA is targeted to the ER (endoplasmic reticulum) in eukaryotic cells. We investigated the processing and membrane association of torsinA and the dystonia-associated Glu-deletion mutant (torsinAdeltaE). We found that the signal sequence of torsinA (residues 1-20 from the 40 amino-acid long N-terminal hydrophobic region) is cleaved in Drosophila S2 cells, as shown by the N-terminal sequencing after partial protein purification. TorsinA is not secreted from S2 cells. Consistently, sodium carbonate extraction and Triton X-114 treatment showed that torsinA is associated with the ER membrane in CHO (Chinese-hamster ovary) cells. In contrast, a variant of torsinA that contains the native signal sequence without the hydrophobic region Ile24-Pro40 does not associate with the membranes in CHO cells, and a truncated torsinA without the 40 N-terminal amino acids is secreted in the S2 culture. Thus the 20-amino-acid-long hydrophobic segment in torsinA, which remains at the N-terminus after signal-peptide cleavage, is responsible for the membrane anchoring of torsinA. TorsinAdeltaE showed similar cleavage of the 20 N-terminal amino acids and membrane association properties similar to wild-type torsinA but, unlike the wild-type, torsinAdeltaE was not secreted in the S2 culture even after deletion of the membrane-anchoring segment. This indicates that the dystonia-associated mutation produces a structurally distinct, possibly misfolded, form of torsinA, which cannot be properly processed in the secretory pathway of eukaryotic cells.
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PMID:Characterization of human torsinA and its dystonia-associated mutant form. 1278 Mar 49

The development of abnormal posturing of the neck or shoulder after local injury has been termed posttraumatic cervical dystonia (PTCD). Certain features seem to distinguish a unique subgroup of patients with this disorder from those with features more akin to typical idiopathic cervical dystonia, such as onset and maximum disability that occurs very quickly after injury, severe pain and a fixed abnormal posture. In an attempt to clarify the nature of this syndrome further, we evaluated 16 such patients (8 men, 8 women). Motor vehicle accident and work-related injuries were common precipitants, with posturing usually developing shortly after trauma, and little progression occurring after the first week. A characteristic, painful, fixed head tilt and shoulder elevation were present in all but one patient, who had a painless elevated shoulder and painful contralateral shoulder depression, as well as nondermatomal sensory loss in 14 patients. Additional abnormalities included dystonic posturing in a limb (2 patients) or jaw (1 patient), limb tremor (3 patients) and "give-way" limb weakness (8 patients). The tremor and the jaw dystonia demonstrated features suggestive of a psychogenic movement disorder, most commonly distractibility. Litigation or compensation was present in all 16 patients. Intravenous sodium amytal improved the posture, pain or both in 13 of 13 patients; in 7 of 13 the sensory deficit either markedly improved or normalized. General anesthesia demonstrated full range of motion in all 5 patients assessed. Psychological evaluations suggested that psychological conflict, stress, or both were being expressed via somatic channels in 11 of 12 tested patients. Our results suggest an important role of psychological factors in the etiology or maintenance of abnormal posture, pain and associated disability of these patients. The role of central factors triggered in psychologically vulnerable individuals after physical trauma is discussed. We propose that the disorder be referred to as "posttraumatic painful torticollis" rather than characterize it as a form of dystonia until further information on its pathogenesis is forthcoming.
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PMID:Posttraumatic painful torticollis. 1467 85

Dystonia is a disorder of involuntary sustained muscle contraction, which usually affects a focal region of the body but may be generalized and results in twisting contorted movements or abnormal postures. Several clinical subtypes of dystonia have been delineated and many have a strong inherited basis. In this issue of Neuron, de Carvalho Aguiar and colleagues report the identification of missense mutations in the gene for the Na+/K+ -ATPase alpha3 subunit (ATP1A3) as a cause of rapid-onset dystonia-parkinsonism (RDP, DYT12).
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PMID:Paying the price at the pump: dystonia from mutations in a Na+/K+ -ATPase. 1526 Sep 53

Rapid-onset dystonia-parkinsonism (RDP, DYT12) is a distinctive autosomal-dominant movement disorder with variable expressivity and reduced penetrance characterized by abrupt onset of dystonia, usually accompanied by signs of parkinsonism. The sudden onset of symptoms over hours to a few weeks, often associated with physical or emotional stress, suggests a trigger initiating a nervous system insult resulting in permanent neurologic disability. We report the finding of six missense mutations in the gene for the Na+/K+ -ATPase alpha3 subunit (ATP1A3) in seven unrelated families with RDP. Functional studies and structural analysis of the protein suggest that these mutations impair enzyme activity or stability. This finding implicates the Na+/K+ pump, a crucial protein responsible for the electrochemical gradient across the cell membrane, in dystonia and parkinsonism.
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PMID:Mutations in the Na+/K+ -ATPase alpha3 gene ATP1A3 are associated with rapid-onset dystonia parkinsonism. 1526 Sep 48

Allelic mutations of Scn8a in the mouse have revealed the range of neurological disorders that can result from alternations of one neuronal sodium channel. Null mutations produce the most severe phenotype, with motor neuron failure leading to paralysis and juvenile lethality. Two less severe mutations cause ataxia, tremor, muscle weakness, and dystonia. The electrophysiological effects have been studied at the cellular level by recording from neurons from the mutant mice. The data demonstrate that Scn8a is required for the complex spiking of cerebellar Purkinje cells and for persistent sodium current in several classes of neurons, including some with pacemaker roles. The mouse mutations of Scn8a have also provided insight into the mode of inheritance of channelopathies, and led to the identification of a modifier gene that affects transcript splicing. These mutations demonstrate the value of mouse models to elucidate the pathophysiology of human disease.
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PMID:Allelic mutations of the sodium channel SCN8A reveal multiple cellular and physiological functions. 1561 59

Early-onset dystonia is caused by mutations in the torsinA protein, a putative member of the AAA+ class of ATPases. In this study we have evaluated the ATPase activity of bacterially expressed wild-type torsinA and its disease-associated mutant forms. Upon overexpression in Escherichia coli, recombinant torsinA proteins were accumulated as insoluble inclusion bodies and required refolding to become soluble and catalytically active. The refolded wild-type and mutant torsinA proteins were capable of hydrolyzing ATP, but their specific ATPase activities differed significantly. Deletions of the amino acid residues E302/303 and F323-Y328 resulted in a decrease of ATPase activity to approximately 35% and approximately 75% of the wild-type level, respectively. ATPase activity of wild-type and mutant torsinA proteins was influenced by factors that varied with cell stress, such as temperature, pH, and ionic strength, and was inhibited by sodium vanadate. Our results provide the first direct evidence for a role of torsinA as an active ATPase and suggest that the mutations in torsinA might affect normal functions of the protein by reducing its enzymatic activity.
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PMID:Dystonia-associated forms of torsinA are deficient in ATPase activity. 1578 71

Sodium oxybate is currently approved in the United States exclusively for the treatment of cataplexy in narcoleptic patients. In a prior article published in this journal, we reported a patient with severe posthypoxic myoclonus whose myoclonus improved with ethanol and also with treatment with sodium oxybate. We extend this preliminary observation to five other patients with ethanol-responsive movement disorders in an open-label, dose-titration, add-on, 8-week trial. All five patients (one with severe alcohol-responsive posthypoxic myoclonus, two with epsilon-sarcoglycan-linked myoclonus-dystonia, and two with essential tremor) experienced improvement from baseline of 50% or greater as measured by blinded videotape review. Tolerability was satisfactory, with dose-dependent sedation as the most common side effect. Further studies of this drug in hyperkinetic movement disorders are warranted.
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PMID:A pilot tolerability and efficacy trial of sodium oxybate in ethanol-responsive movement disorders. 1598 20

The results of clinical, neuropsychological and MRI study of 21 patients with "ephedron" encephalopathy caused by intake of methcatinon ("ephedron"), a surrogate drug obtained from phenylpropanolamine-containing compounds by adding potassium permanganate, are presented. Signs of brain lesions emerged 3-14 (mean 6.8 +/- 4.9) months after the beginning of the regular drug intake. Neurological disturbances were measured using the Scale of clinical assessment of ephedron encephalopathy. In the acute stage of the disease, most patients had the combination of extrapyramidal disorders (parkinsonism, muscular dystonia, tremor, myoclonia) with pronounced postural instability, pseudobulbar syndrome, autonomic, cognitive and affective personality abnormalities of subcortical and frontal types. In 18 (86%) patients, MRI revealed a bilateral symmetric elevation of the signal from the basal ganglia on T1-weighted images, mostly from the medial segment of globus pallidus and the reticular part of substantia nigra that reflected magnesium accumulation. The spread of hyperintensive MRI changes negatively correlated with the disease duration (r = -0.6; p < 0.01), but did not depend on the drug abuse duration or its approximate total dosage, and also did not correspond to the disease severity. In follow-up, a tendency to spontaneous regress of symptoms was observed in 29% of the cases, and in 33% patients symptoms have been regressing even 4 years after stopping of methcatinon intake. The main mechanisms of "ephedron" encephalopathy development are probably related to the manganese accumulation in the brain that might trigger secondary pathogenetic mechanisms, such as mitochondrial dysfunction, oxidative stress, etc. The induction courses of calcium and sodium EDTA that accelerates manganese excretion decrease a probability of the further disease progress, though do not contribute significantly to symptoms regress. The data on possibilities of symptomatic therapy of movement and affective disturbances is presented.
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PMID:["Ephedron" encephalopathy]. 1611 41

Rapid-onset dystonia-parkinsonism (RDP, DYT12) is one of the fifteen genetic types of dystonia. Its' transmission is autosomal dominant with reduced penetrance. Onset of RDP is abrupt and occurring usually in the second decade of life, sometimes with preceding transient episods of dystonia. Clinical course of the disease is stationary, but the disease in most of the cases leads to seroius neurololgic disability. Previous haplotypic analyses have shown that RDP is linked to markers on chromosome 19q13. The last year it was found that the mutated gene is the one for the NA+/K(+)-ATPase alpha3 subunit (ATP1A3), (one of the sodium pumps). One of the six families described so far was identified in Poland.
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PMID:[Rapid-onset dystonia-parkinsonism]. 1651 24

This article provides an overview of news about the Na+,K+ pump, an indispensable enzyme whose protein structure has been described in a recent article in Nature, 50 years after its discovery. In combination with mutational analysis, the structure reveals the binding pocket for the K+ ions and the regulation of Na+ transport by a strategically located C-terminus of the protein. Focus is also on the pathophysiology of two neurological disorders, familial hemiplegic migraine and rapid-onset dystonia-parkinsonism, recently shown to be caused by mutations in the Na+,K+-ATPase.
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PMID:[The Na+,K+ pump continues to cause surprise]. 1849 48


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