Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Myoclonus epilepsy with ragged-red fibers (MERRF) has been shown to be associated with a specific point mutation at the nucleotide 8344 in the tRNA(Lys) gene of mitochondrial DNA (mtDNA). We screened 6 patients with clinically diagnosed MERRF and 1 patient with ocular myopathy for point mutations in the tRNA(Lys) gene, using single strand conformation polymorphism (SSCP) analysis, which can detect even a 1-basepair difference between 2 DNA sequences. Using SSCP and consequent DNA sequencing, we identified the known MERRF mutation in 4 out of 6 MERRF patients, as well as in 1 patient with a new clinical phenotype associated with this mutation: progressive external ophthalmoplegia, muscle weakness and a lipoma, but no myoclonus or epilepsy. Two of the patients with clinical MERRF had neither the MERRF-mutation nor any other mutations in the tRNA(Lys) gene. Using SSCP analysis, we also detected a new polymorphism in 1 patient. Thus, SSCP analysis can be applied to search effectively and rapidly for point mutations or polymorphisms in mitochondrial DNA.
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PMID:Use of single strand conformation polymorphism analysis to detect point mutations in human mitochondrial DNA. 143 90

A 55-year-old man is presented who developed severe multifocal myoclonus and tonic clonic seizures in his early thirties, and progressive limb weakness in his mid forties, when a ragged red fibre myopathy was diagnosed. He went on to develop a distal motor neuropathy and respiratory failure. Respiratory function tests indicated respiratory failure secondary to respiratory muscle weakness and a central hypoventilation syndrome. CT scan revealed brain stem atrophy and brain stem evoked responses were abnormal. A sural nerve biopsy showed severe axonal degeneration. Cytochrome difference spectra and polarographic studies on isolated intact muscle mitochondria were normal. This study reports the association of respiratory failure and sleep apnoea with Fukuhara's syndrome and presents biochemical data suggesting that the mitochondrial respiratory chain may be intact in some patients with this syndrome.
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PMID:Mitochondrial myoneuropathy with respiratory failure and myoclonic epilepsy. A case report with biochemical studies. 393 3

We studied a patient with somatic growth failure with easy fatigability, myopathy with mitochondrial abnormality, increased lactate and pyruvate in blood and CSF, mental retardation, seizure, myoclonus, deafness, cerebellar ataxia, and blindness with macular degeneration and optic atrophy. Pathologic findings included multiple brain infarctions and massive calcification in the basal ganglia. Biochemical studies of isolated mitochondria revealed decreased oxygen consumption in skeletal muscle, diaphragm, and brain, suggesting an abnormality in the respiratory chain.
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PMID:Mitochondrial encephalomyopathy with lactate-pyruvate elevation and brain infarctions. 653 55

We describe 2 sibs (brother and sister) with myopathy, sideroblastic anemia, lactic acidosis, mental retardation, microcephaly, high palate, high philtrum, distichiasis, and micrognathia. Very low levels of cytochromes a, b, and c were detected in the patients' muscle mitochondria. Deposition of iron within the mitochondria of bone marrow erythroblasts was observed on electron microscopy. Irregular and enlarged mitochondria with paracrystalline inclusions were also seen on electron microscopy of the patients' muscle specimen. Examination of DNA from the affected sibs showed no deletions in the mitochondrial DNA nor the mutations identified in the syndromes of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) or myoclonus, and epilepsy associated with rugged-red fibers (MERRF). Since the parents were first cousins and 2 of 6 sibs (male and female) were affected, we suggest that the syndrome expressed by our patients represents a previously unknown autosomal recessive disorder that includes mitochondrial myopathy, lactic acidosis, and sideroblastic anemia.
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PMID:Myopathy, lactic acidosis, and sideroblastic anemia: a new syndrome. 772 39

In the last 4 years much progress has been made in the understanding of mitochondrial disorders. Point-mutations, deletions and depletion of the mitochondrial genome are associated with disorders like Leber's disease, MERRF (Myoclonus Epilepsia with Ragged Red Fibers), MELAS (mitochondrial Myopathy, Encephalopathy, Lactic acidosis and Stroke-like episodes) and several others. Recently, mitochondrial dysfunctions have been also related to neurodegenerative disorders like Parkinson's disease and to aging. Since the brain depends mostly on mitochondrial energy supply, mitochondrial dysfunctions may affect the nervous system more severely than other tissues causing or worsening diseases and playing a role in the biological deterioration of aging. Furthermore, the mitochondrial energy supply is associated with the production of highly reactive oxygen species. Ninety-five percent of the molecular oxygen is metabolized within the mitochondria by the electron-transport chain so that mitochondria are highly exposed to oxidative stress which may damage selected neuronal populations. Oxygen radicals created during respiration induce mitochondrial dysfunction which accelerates the production of more deleterious species of oxygen. The latter step further increases mitochondrial malfunction, thus intensifying and perpetuating the cycle. These two mechanisms combined may lead to cell death in brain and other tissues with high metabolic rate. Therefore, in neurodegenerative disorders such as Parkinson's disease mitochondrial dysfunction and oxidative stress may cause or worsen the clinical features.
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PMID:Oxidative stress and mitochondrial dysfunction in neurodegeneration. 784 18

We looked for the A-->G transition at position 8344 of mtDNA in 150 patients, most of them with diagnosed or suspected mitochondrial disease, to assess the specificity of this mutation for the MERRF phenotype, to define the clinical spectrum associated with the mutation, and to study the relationship between percentage of mutation in muscle and clinical severity. Our results confirm the high correlation between the A-->G transition at position 8344 and the MERRF syndrome, but they also show that this mutation can be associated with other phenotypes, including Leigh's syndrome, myoclonus or myopathy with truncal lipomas, and proximal myopathy. The absence of the mutation in four typical MERRF patients suggests that other mutations in the tRNA(Lys) gene, or elsewhere in the mitochondrial DNA, can produce the same phenotype.
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PMID:Clinical features associated with the A-->G transition at nucleotide 8344 of mtDNA ("MERRF mutation"). 817 May 67

Fourteen patients (10 boys, 4 girls) aged from 4 months to 14 years old were diagnosed with mitochondrial disease based on the clinical manifestations together with abnormal muscle mitochondrial morphologies. Their clinical diagnoses included Leigh syndrome, three; Menkes' syndrome, three; Kearns-Sayre syndrome, two; myoclonic epilepsy with ragged fibres, one; and infant-onset progressive myoclonic epilepsy, one; fatal infantile mitochondrial myopathy, one; fatty acid oxidation defect, two; and myopathy with cardiopathy, one. Organs involved other than muscles included central nervous system, ten; heart, six; eye, two; liver, two; and kidney, two. Clinical manifestations varied to include hypotonia, seizures, myoclonus, mental retardation, nystagmus, ataxia, ptosis, ophthalmoplegia, retinal degeneration, muscle atrophy, spasticity etc. Nine had an abnormal rise in lactate after glucose loading. Ragged-red fibres were found in four patients. Abnormal mitochondrial morphology included abnormal accumulation, abnormal cristae pattern of tubular, concentric, or parallel form, some contained osmiophilic inclusion bodies. One patient of Leigh syndrome had had brain necropsy which showed intramyelin splitting of myelinated axons.
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PMID:Clinical manifestation of mitochondrial diseases in children. 821 54

Ten patients, two men and eight women with mitochondrial encephalomyopathy, had an A-G mutation at nucleotide pair 8,344 in the mitochondrial DNA, the most common genetic defect in myoclonus epilepsy with ragged-red fibers (MERRF). Eight patients had the clinical and pathologic characteristics of MERRF including myoclonus, seizures, cerebellar ataxia and myopathy with ragged-red fibers. Two patients had atypical symptoms such as early onset of fatal cardiac failure and late onset of rapid mental deterioration, respectively. The striking feature in our patients with the 8,344 mutation cardiac involvement and two developed progressive heart failure. In the typical MERRF patients, the proportion of mutant mitochondrial DNA in their skeletal muscles, quantified by a single strand conformation polymorphism analysis, was above 85%. However, there was no significant correlation between clinical severity, histopathological findings and the proportion of mutant mtDNA in muscle biopsy samples, suggesting that non-ragged-red fibers play an important role in the phenotype expression of the mutants.
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PMID:The 8,344 mutation in mitochondrial DNA: a comparison between the proportion of mutant DNA and clinico-pathologic findings. 858 Jul 30

Type 1 antineuronal nuclear autoantibody (ANNA-1, also known as "anti-Hu") is a marker of neurologic autoimmunity that is highly associated with small-cell lung carcinoma (SCLC). To determine the spectrum of symptoms and signs as well as the frequency of cancer in adult patients who are seropositive for ANNA-1, we reviewed 162 sequential patients (67% female) identified as ANNA-1-positive in a comprehensive immunofluorescence screening test. In 21% of these patients, the antibody test requested by the physician was not ANNA-1. By the end of the follow-up period, cancer had been found in 142 patients (88%). Ten of these lacked evidence of SCLC (4 had prostate carcinoma, 3 breast carcinoma, 1 both prostate carcinoma and melanoma, 1 lymphoma, and 1 squamous-cell lung carcinoma). Of the 132 patients (81%) with proven SCLC, 17 had one or more coexisting malignant neoplasms (6 had renal carcinoma, 4 another lung primary carcinoma, 3 prostate carcinoma, 3 breast carcinoma, and 4 assorted neoplasms). The diagnosis of SCLC in 128 patients (97%) followed the onset of paraneoplastic symptoms. SCLC was identified in 10 patients by chest MRI after an equivocal chest radiograph or CT; in 28 by bronchoscopy, mediastinoscopy, or thoracotomy; and in 7 at autopsy. Neurologic signs in decreasing frequency were neuropathy (sensory > mixed somatic > autonomic > cranial [especially cranial nerve VIII] > motor), cerebellar ataxia, limbic encephalitis, polyradiculopathy, associated Lambert-Eaton myasthenic syndrome, myopathy, myelopathy, opsoclonus/myoclonus, motor neuronopathy, brachial plexopathy, and aphasia. Nineteen patients had a solely gastrointestinal initial presentation, including gastroparesis, pseudo-obstruction, esophageal achalasia, or other dysmotility. We conclude that seropositivity for ANNA-1 can expedite the diagnosis and treatment of otherwise occult cancer in patients, especially tobacco abusers, with varied neurologic and gastroenterologic presentations. The search for SCLC should not end on discovering a different neoplasm.
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PMID:Paraneoplastic and oncologic profiles of patients seropositive for type 1 antineuronal nuclear autoantibodies. 952 Dec 51

To define the incidence and type of neurological complications and associated factors, we reviewed 41 consecutive patients who had 45 procedures for liver transplantation. Encephalopathy occurred after 28 procedures (62%) with immediate onset and no significant recovery before death or re-transplantation in 11 (24%), slow recovery in eight (18%) and delayed onset (1-50 days, average 11) in six (13%). Intermittent confusion and agitation with full recovery followed three (6.6%), and focal and generalized seizures followed five (11%) procedures with multifocal myoclonus in two and status epilepticus in one; isolated focal seizures followed two and myoclonus or unclassified seizures, one each. All patients with seizures had encephalopathy. Three patients had neuropathy (2 generalised and 1 focal). Other complications included headache (2), tremors (2), fatigue (2), restlessness, nervousness, transient enuresis, intermittent dizziness, critical illness myopathy and detached retina. Brain imaging showed atrophy in three (6.6%) instances, intracerebral haemorrhage in two, multiple infarctions in one, and intracerebral and subarachnoid haemorrhage with infarction in one. Cerebrospinal fluid analysis showed increased protein in three, hemorrhage in one, and no abnormality in one patient. Of 12 patients (29%) who died before discharge, five in the first and three in the second week post-transplantation, 11 (92%) had encephalopathy post-operatively. Neurological complications after transplantation were associated with increased mortality. Post-operative hypomagnesaemia was associated with the development of nervous system complications. We did not identify any clear pre-operative predictors of development of post-operative neurological complications.
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PMID:Neurological complications in liver transplantation. 1201 80


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