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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe a young man with a progressive neurological disorder including myoclonus, mental retardation, muscle weakness and a mitochondrial myopathy (myoclonus epilepsy and ragged red fibres--MERRF). Multiple abnormalities of the mitochondrial respiratory chain in skeletal muscle are shown by direct measurement of the flux through the individual complexes, low-temperature redox spectroscopy and decreased immunodetectable subunits of complexes I and IV by immunoblotting. No abnormality of mitochondrial DNA was found. This is the first report of combined defects of complexes I, III and IV as a cause of this clinical syndrome. However, we propose that the occurrence of multiple respiratory chain defects may be more common than previously recognised and that this particular combination of defects, involving complexes I, III and IV, may be the predominant biochemical abnormality in MERRF.
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PMID:Multiple defects of the mitochondrial respiratory chain in a mitochondrial encephalopathy (MERRF): a clinical, biochemical and molecular study. 164 12

Twelve patients with histologically defined mitochondrial myopathy are described. There were 9 males and 3 females. The age of onset ranged from birth to 35 years with a median of 14 years. The most common clinical picture was that of ophthalmoplegia, ptosis and muscle weakness found in 10 patients. One presented with exercise intolerance due to muscular aches and pains, and the other besides his muscular weakness had mental retardation and an aggressive behavior. The clinical presentation and differential diagnosis of these patients are discussed.
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PMID:[Mitochondrial myopathy: report of 12 cases with histochemical study of the skeletal muscle]. 180 26

Two patients with mitochondrial encephalomyopathy (MEP) serve to emphasize the variability of this group of diseases. Cerebral insults, mitochondrial cardiopathy, relapsing ileus, cerebral angioma, ataxia, and myoclonic seizures characterized the first case of an adult man with similar diseases in his family, interpreted as transitional form between mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and myoclonus epilepsy associated with ragged red fibers (MERRF). The second patient, a floppy infant with cardiomyopathy and myoclonism, statomotoric and mental retardation showed combined defects in mitochondrial respiratory chain at NADH-CoQ reductase and cytochrome c oxidase and a deficiency of carnitine. In both patients neuropathologically criteria of Leigh's syndrome could be demonstrated in the cerebral cortex, in case 2 also clinically. The classificatory problems of the relationships between KSS, MELAS, MERRF, Leigh's as well as Alpers' syndromes are discussed.
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PMID:Mitochondrial myopathies with necrotizing encephalopathy of the Leigh type. 322 73

We report here two cases in a family with pleomorphic clinical features which include mitochondrial myopathy, encephalopathy, stroke-like episodes, episodic disturbances of consciousness and other multisystemic abnormalities. The other signs observed in multisystemic abnormalities were ophthalmoplegia, short stature, diabetes mellitus, diabetes insipidus, renal dysfunction, optic atrophy, retinal degeneration, impairment of hearing and mental retardation or deterioration. A symptomatological variation was observed in cases in the same family. It is suggested that these widely varying symptoms may be expressions caused by a common biochemical defect which involves different tissues in different individuals in the family. The syndromes observed in the present cases were compared with other possibly-related mitochondrial encephalomyopathies.
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PMID:Familial mitochondrial encephalomyopathy with stroke-like episodes and episodic disturbances of consciousness: a study of pedigree including three generations with multisystemic abnormalities. 362 95

An A to G transition at nucleotide 3,243 in the tRNA(Leu(UUR)) gene of mitochondrial DNA (mtDNA) has been suggested to be the disease-related mutation for MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes). Recently, the same mutation has also been found in several pedigrees with maternally inherited diabetes mellitus and sensorineural deafness. We report here a family showing the association of deafness and diabetes mellitus, as the predominant clinical features, with this mutation. The mutation was detected by restriction-enzyme analysis of the relevant PCR-amplified segment of the mtDNA, in two generations. In this family, it is noteworthy that two members with the mutation had some symptoms of MELAS such as short stature, seizures and mental retardation and that one had no clinical symptoms though the mtDNA mutation was identified in his blood. The findings in this family demonstrate the diversity of clinical expression of the mtDNA mutation and suggest that a combination of sensorineural deafness and diabetes mellitus is only one typical presentation of the various phenotypic features caused by the 3,243 mutation.
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PMID:[Detection of a mutation in mitochondrial DNA in a family with sensorineural deafness and diabetes mellitus as the predominant clinical features]. 756 31

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

We examined the clinical and biochemical features of 27 cases with acute myoglobinuria who had been suspected of having metabolic myopathies. The systematic biochemical studies included the measurements of 13 glycolytic enzymes, mitochondrial respiratory chain enzymes, carnitine palmitoyltransferase (CPT) and 5 enzymes of fatty acid beta-oxidation. Enzyme defects were found in 9 patients using muscle biopsy specimens: phosphorylase deficiency in 3, CPT deficiency in 4 and phosphoglycerate kinase deficiency in 2. One patient was diagnosed as MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) with the histopathological examination and clinical data. A suspicion of beta-oxidation disorder was entertained in some patients of which the activities were about 50% of control means. However, no evidence to substantiate its significance as the enzyme defects was obtained from our data. Sixteen of 17 undiagnosed cases could be divided into two groups according to precipitating factors as follows: one had exercise as the factors and the other had infection. These groups also showed some differences in clinical features. In the infection group, myoglobinuria tended to progress more rapidly and was occasionally followed by acute renal failure. And some cases had additional associated conditions such as mental retardation or epilepsy. On the other hand, the exercise group had only myopathic symptoms. The difference in these clinical features between the two groups suggested that they had the different pathogenic mechanisms respectively.
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PMID:[Clinical and biochemical analysis of 27 patients with myoglobinuria of unknown causes]. 778 Dec 10

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

We report the seventh case of autosomal recessive inherited mitochondrial myopathy, lactic acidosis, and sideroblastic anemia The patient, a product of consanguineous Persian Jews, had the association of mental retardation, dysmorphic features, lactic acidosis, myopathy, and sideroblastic anemia. Muscle biopsy demonstrated low activity of complexes 1 and 4 of the respiratory chain. Electron microscopy revealed paracrystalline inclusions in most mitochondria. Southern blot of the mitochondrial DNA did not show any large-scale rearrangements. The patient was found to be homozygous for the 656C-->T mutation in the pseudouridine synthase 1 gene (PUS1). Mitochondrial myopathy, lactic acidosis, and sideroblastic anemia is an oxidative phosphorylation disorder causing sideroblastic anemia, myopathy, and, in some cases, mental retardation that is due to mutations in the nuclear-encoded PUS1 gene. This finding provides additional evidence that mitochondrial ribonucleic acid modification impacts the phenotypic expression of oxidative phosphorylation disorders.
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PMID:Mitochondrial myopathy, sideroblastic anemia, and lactic acidosis: an autosomal recessive syndrome in Persian Jews caused by a mutation in the PUS1 gene. 1597 56

Lactic acidosis has been associated with a variety of clinical conditions and can be due to mutation in nuclear or mitochondrial genes. We performed mutations screening of all mitochondrial tRNA genes in 44 patients who referred as hyperlactic acidosis. Patients showed heterogeneous phenotypes including Leigh disease in four, MELAS in six, unclassified mitochondrial myopathy in 10, cardiomyopathy in five, MERRF in one, pure lactic acidosis in six, and others in 12 including facio-scaplo-femoral muscular dystrophy (FSFD), familial cerebellar ataxia, recurrent Reye syndrome, cerebral palsy with mental retardation. We measured enzymatic activities of pyruvate dehydrogenase complex, and respiratory chain enzymes. All mitochondrial tRNA genes and known mutation of ATPase 6 were studied by single strand conformation polymorphism (SSCP), automated DNA sequence and PCR-RFLP methods. We have found one patient with PDHC deficiency and six patients with Complex I+IV deficiency, though the most of the patients showed subnormal to deficient state of respiratory chain enzyme activities. We have identified one of the nucleotide changes in 29 patients. Single nucleotide changes in mitochondrial tRNA genes are found in 27 patients and one in ATPase 6 gene in two patients. One of four pathogenic point mutations (A3243G, C3303T, A8348G, and T8993G) was identified in 12 patients who showed the phenotype of Leigh syndrome, MELAS, cardimyopathy and cerebral palsy with epilepsy. Seventeen patients have one of the normal polymorphisms in the mitochondrial tRNA gene reported before. SSCP and PCR-RFLP could detect the heteroplasmic condition when the percentage of mutant up to 5, however, it cannot be observed by direct sequencing method. It is important to screen the mtDNA mutation not only by direct sequence but also by PCR-RFLP and the other sensitive methods to detect the heroplasmy when lactic acidosis has been documented in the patients who are not fulfilled the criteria of mitochondrial disorders.
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PMID:Mitochondrial tRNA gene mutations in patients having mitochondrial disease with lactic acidosis. 1633 22


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