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We describe a sporadic case of adult-onset, complex I deficiency mitochondrial encephalomyopathy (MEM), the clinical and pathological features of which failed to fit any of the known subgroups of MEM, such as Kearns-Sayre syndrome, mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes or myoclonus epilepsy with ragged-red fibers. Clinically, this patient had only progressive cerebellar ataxia, generalized muscle weakness and hearing loss. The principal finding at autopsy was degeneration of the olivo-ponto-cerebellar system. This case suggests that mitochondrial disease could underlie some cases of olivo-ponto-cerebellar atrophy.
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PMID:An autopsy case of mitochondrial encephalomyopathy with prominent degeneration in olivo-ponto-cerebellar system. 179 71

Several reports showed that abnormality of mitochondrial DNA (mt DNA) can be an etiology of cardiomyopathy in recent years. Cardiac involvement in mitochondrial disease other than Kearns-Sayre syndrome (KSS), however, has not been documented clearly. Therefore, cardiac involvement, abnormality of mt DNA and defects of the respiratory chain in mitochondrial disease were studied. Thirty-eight patients with mitochondrial disease were studied. The patients were consisted of 2 patients with KSS, 1 patient with probable KSS, 15 patients with ocular myopathy, 1 patient with myoclonus epilepsy with ragged-red fibers (MERRF), 6 patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), 5 patients with undefined mitochondrial encephalomyopathy and 8 patients with mitochondrial myopathy. Cardiac involvement was evaluated by electrocardiogram (ECG), chest roentgenogram and echocardiogram. Abnormality of mt DNA was examined using Southern blotting and polymerase chain reaction method in 25 patients. Defects of the respiratory chain were examined in 27 patients. All of the KSS and probable KSS showed heart block, and 2 of the 3 patients showed abnormalities on echocardiogram. Five of the 15 patients with ocular myopathy showed abnormalities on EGG. Four of the 6 patients with MELAS showed abnormalities on ECG, 1 showed cardiomegaly, and 3 showed left ventricular hypertrophy on echocardiogram. Three of the 5 patients with undefined mitochondrial encephalomyopathy showed abnormalities on ECG, 2 showed cardiomegaly and 2 showed asymmetric septal hypertrophy and wall motion abnormalities on echocardiogram. Large-scale deletions of mt DNA were detected in all of the KSS and probable KSS, and 7 patients with ocular myopathy. Deletions of mt DNA in the skeletal and cardiac muscles were proved to be identical in a case of KSS. A point mutation in mt DNA was detected in 5 patients with MELAS. Defects of the respiratory chain were detected in 22 patients. In conclusion, cardiac involvement is frequently seen in mitochondrial disease. Abnormality of ECG, especially heart block, is characteristic of KSS. Left ventricular hypertrophy is characteristic of mitochondrial encephalomyopathy.
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PMID:[Cardiac involvement in mitochondrial disease: a clinical study of 38 patients]. 182 6

A case of mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes, in which a pituitary growth hormone (GH) secretion deficiency of hypothalamic origin was revealed through neuro-endocrinological examinations, was described. The case was a 10-year-old girl, who had been suffering from generalized tonic seizures since age 5, four episodes of alternating hemiplegia since age 6, stunted growth since age 7, and simple partial motor seizures as well as gelastic seizures since age 8. Marked elevation of lactate and pyruvate in both serum and CSF, abundant ragged red fibers in biopsied muscle, and low density areas in the left occipital lobe and bilateral globus pallidus in addition to diffuse brain atrophy on CT scan and MRI of the head were demonstrated, although the activities of muscle enzymes complex I-IV were within normal ranges. Pituitary GH secretion was deficient under the loadings with insulin, L-DOPA, sleep, and a single growth hormone releasing factor (GRF) administration, but normal GH response was registered under the repetitive stimulation with GRF. Activities of other hormonal axes were normal. It is likely that short stature commonly observed in MELAS patients is due to hypothalamic dysfunction, which might be brought out by chronic ischemia and energy deficiency of the diencephalon based upon mitochondrial abnormality of that region. It is likely that gelastic seizure in this case is due to hypothalamic dysfunction.
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PMID:[Hypothalamic GH Deficiency and gelastic seizures in a 10-year-old girl with MELAS]. 187 57

Intramuscular blood vessels were examined with succinate dehydrogenase stain in skeletal muscle biopsy specimens from 6 patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). Almost all arteries had large granular deposits with high succinate dehydrogenase activity in their walls. Electron microscopic examination of serial frozen sections of these biopsies showed that the smooth muscle cells of the strongly succinate dehydrogenase-reactive blood vessels contained markedly proliferated mitochondria, characteristic of patients with MELAS. The presence of strongly succinate dehydrogenase-reactive blood vessels in muscle biopsy specimens provides an important clue toward understanding the underlying pathogenetic mechanism in patients with MELAS as well as another approach to the diagnosis of this disorder.
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PMID:Strongly succinate dehydrogenase-reactive blood vessels in muscles from patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. 189 63

A 9-year-old girl and an 11-year-old boy had ptosis, progressive external ophthalmoplegia, pigmentary retinopathy, and sensorineural hearing loss. The girl had diabetes mellitus and the boy had hypoparathyroidism. Both children also developed recurrent vomiting and cerebral infarcts with lactic acidosis. Muscle biopsy specimens showed ragged-red fibers and Southern analysis demonstrated a distinct heteroplasmic deletion of muscle mitochondrial DNA in each patient but no evidence of the point mutation in the transfer RNALeu(UUR) gene recently identified in mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). These 2 children had combined features of Kearns-Sayre syndrome and MELAS, suggesting that mitochondrial DNA deletions occasionally can have pleomorphic clinical expression.
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PMID:Deletion of mitochondrial DNA in patients with combined features of Kearns-Sayre and MELAS syndromes. 189 71

The total sequences of mitochondrial DNA were determined in two patients with juvenile-onset mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) due to Complex I deficiency. Patients 1 and 2 had three and two unique point mutations, respectively, causing replacement of phylogenically conserved amino acids. A transition from G to A was found at nucleotide position 5601 in the alanine tRNA gene of Patient 2, and a transition from A to G was found at 3243 in the leucine (UUR) tRNA gene of both patients. The latter mutation located at the phylogenically conserved 5' end of the dihydrouridine loop of the tRNA molecule, and was present in two patients with adult-onset MELAS and absent in controls. These results indicate that a mass of mtDNA mutations including the A-to-G transition in the tRNA(Leu) gene is a genetic cause of MELAS.
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PMID:Mitochondrial DNA mutations in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). 189 74

Mitochondrial respiratory chain function was investigated with polarographic and enzymatic studies, and correlated with immunoblot studies using a battery of probes against respiratory chain holocomplexes in a series of patients with myoclonus epilepsy and ragged red fibers (MERRF) syndrome. State III respiration rates in intact skeletal muscle mitochondria were normal in two cases, suggested site I deficiency in one case and a mid-respiratory defect in another. Immunological studies of complex I showed reduced levels of several subunits with the apparent absence of two bands (which at 45 and 42 kDa, coincide with the predicted electrophoretic mobility of the ND5 gene product) in one case. Complex I, III and IV composition was normal in the other three cases indicating no major disruption of complex assembly. A differing severity of skeletal muscle respiratory chain impairment in a group of unrelated patients with severe cerebral clinical involvement is best explained by uneven tissue distribution between brain and muscle of a heteroplasmic mtDNA mutation. The relationship between MERRF and mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) encephalopathies is reappraised by extension of this hypothesis.
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PMID:Functional respiratory chain studies in mitochondrial cytopathies. Support for mitochondrial DNA heteroplasmy in myoclonus epilepsy and ragged red fibers (MERRF) syndrome. 190 54

A 24-year-old male had a deficiency of the complex I (NADH coenzyme-Q-reductase) of the mitochondrial respiratory chain, which clinically presented as a mitochondrial encephalomyopathy, with lactic acidosis and stroke-like episodes (MELAS syndrome). The encephalopathic episodes were preceded by migraine and were characterized by focal deficit signs, motor partial seizures and hypodense areas in the CT scan. An echocardiographic diagnosis of hypertrophic cardiomyopathy without intracavitary thrombi was made. It is suggested that hypertrophic cardiomyopathy is caused by the mitochondrial abnormalities that have been reported in the myocardium, and that migraine and cerebral infarctions are associated with abnormalities in the mitochondria from the endothelium and smooth muscle fibres of the cerebral small arteries and arterioles.
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PMID:[Complex I (NADH coenzyme-Q-reductase) deficiency, MELAS syndrome and hypertrophic cardiomyopathy]. 190 55

EEG was studied in 25 children and adolescents with mitochondrial encephalomyopathies, defined on the basis of clinical, biochemical and morphological criteria. Twenty cases conformed to well-known mitochondrial syndromes: Alpers syndrome [6], Leigh syndrome [2], MERRF (myoclonus epilepsy and ragged red fibers) syndrome [3], MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) syndrome [5] and Kearns-Sayre syndrome [4]. Many patients were followed for several years with repeated EEG. In all, 112 EEG records were included in the study. A common feature of all the mitochondrial encephalomyopathic syndromes was slowing of the alpha rhythm. Epileptic discharges were seen in most syndromes. In spite of the small number of cases in each group, in Alpers, MERRF and MELAS syndromes we found sequential EEG patterns which seemed to be typical of the respective syndromes. In contrast, in Kearns-Sayre syndrome, a slow background rhythm was the only consistent finding. We conclude that EEG, especially repeated recordings, may be of help in the diagnostic evaluation of mitochondrial encephalomyopathies.
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PMID:EEG findings in children and adolescents with mitochondrial encephalomyopathies: a study of 25 cases. 192 9

A six-month-old boy with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome developed repeated crops of purpuric macules on his soles and palms, which were histologically identified as hemorrhage into the dermis without inflammatory infiltrates. Transmission electron microscopy of the skin eruptions revealed various stages of endothelial degeneration in the dermal capillaries associated with consequent extravasation of erythrocytes. The degenerative change was characterized by swollen and vacuolated mitochondria which showed disintegration of their cristae. These morphological changes in the mitochondria of the endothelial cells resembled those seen in skeletal muscle fibers. Similar changes were also noted in other tissues of the skin, such as the axons of myelinated peripheral nerves and some of the keratinocytes in the epidermis. Although these fine structural features are difficult to differentiate from artifacts, abnormal mitochondria could result in functional disturbance particularly in the tissues that require relatively high kinetics, and thus contribute the symptoms of myopathy, encephalopathy, acidosis and stroke-like episodes.
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PMID:Purpuric cutaneous manifestations in mitochondrial encephalomyopathy. 193 57


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