Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0162671 (MELAS)
 587 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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.
 ...
PMID:EEG findings in children and adolescents with mitochondrial encephalomyopathies: a study of 25 cases. 192 9

Among 40 patients with ragged red fibers in muscle biopsy, all but two met criteria for one of the recognized mitochondrial myopathies: Kearns-Sayre syndrome (6 patients); other ophthalmoplegias (17): MELAS (3); MERRF (2); limb myopathy (5); and exercise intolerance (3). Two patients had MNGIE (mitochondrial myopathy with neuropathy, gastrointestinal symptoms and encephalopathy) and one had spinal muscular atrophy. The myopathy had features of facioscapulohumeral dystrophy in 4 patients. This analysis provides 4 lines of evidence to reinforce the view that, despite occasional "overlap" cases, distinct syndromes can be recognized. First, there are clinical differences. Second, KSS is almost never familial but MELAS and MERRF are often familial. Third, in this series, as in others, all deletions of mtDNA were found in patients with either KSS or non-familial PEO. With a possible single exception, none of the familial cases had KSS and no familial cases included a deletion of mtDNA. Others have found evidence of mtDNA point mutations in MERRF, and maternal inheritance suggests that point mutations will be found in MELAS. Finally, postmortem findings differ in KSS, MELAS, and MERRF. For all of these reasons, we believe it is useful to separate cases on clinical grounds. Deletions and point mutations of mtDNA are becoming defining characteristics of these syndromes.
 ...
PMID:Clinical syndromes associated with ragged red fibers. 196 52

Two 30-year old twins, one male, the other female, were followed up for 20 years for predominantly proximal muscular deficit without increase of muscle enzymes. The lactic acid level was elevated at rest and further increased during exercise. Muscle biopsy revealed mitochondrial abnormalities. Encephalopathy was also present. The female patient had been treated, at the age of 10 years, for myoclonic attacks which regressed when she was over 18 years. None of the two patients had dementia. CT and MRI showed very extensive and symmetrical lesions of the white matter which did not involve the basal ganglia. These two cases are interesting on three scores: (1) clinically, the woman exhibited symptoms of the MELAS syndrome (without cerebral vascular accidents) and symptoms of the MERRF syndrome, which suggests the existence of borderline cases; (2) genetically, our cases were in favour of a so-called "maternal" heredity (boys are affected in all cases): here both sexes were involved but the phenotype varied; (3) biochemically, we found no enzyme activity deficit likely to explain the clinical features. The significance of a selective increase of cytochrome c oxidase in both mother and daughter is unclear.
 ...
PMID:[Mitochondrial myopathy and leukoencephalopathy in twins of different sexes]. 196 56

A 32 year-old diabetic woman presented with an acute coma followed by epileptic seizures, aphasia and constructive apraxia. No ischemic lesion was demonstrated by CT scan and carotid angiograms. The other investigations showed sensorineural hearing loss, retinal degeneration, calcifications of the basal ganglia and lactic acidosis. The follow-up was marked by pseudo-dementia with personality disorders, memory deficits, behavioural changes, migrainous and epileptic features. Although there was no sign of muscular deficiency, a muscular biopsy showed characteristic ragged-red fibers and mitochondrial abnormalities at electron microscopy. The muscular biopsy enables us to classify this case as a mitochondrial encephalopathy similar to the MELAS syndrome. The stroke-like episodes are probably caused by a specific angiopathy involving the mitochondria of brain vessels.
 ...
PMID:[Mitochondrial encephalopathy affecting only the central nervous system]. 196 61

The last two decades have revealed a novel group of inborn errors with defects on the pathways of aerobic energy substrates into the mitochondria or the capacity to generate reducing potential from these substrates, as well as those that block the oxidative phosphorylation pathway itself. The mitochondrial diseases are clinically heterogenous disorders that can affect multiple organ systems, mainly the skeletal muscle and nervous system (mitochondrial encephalomyopathies). There are a few distinctive syndromes such as Leigh's syndrome, Alper's syndrome, Kearns-Sayre's syndrome, myoclonus epilepsy with "ragged-red fibres" (MERRF), and MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, strokelike episodes). The last year our department has evaluated ten children with mitochondrial disorders. Among these are two siblings with Leigh's syndrome and cytochrome c-oxidase defect. The first child, a girl, developed the first symptoms at the age of four months and died 13 months old. The younger brother showed the same clinical picture as his sister. However, the clinical neurological picture was stabilized when he was 18 months old, and he is still alive at six years of age and slightly psychomotorically retarded.
 ...
PMID:[Mitochondrial diseases--more common than we realize?]. 199 73

The MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) can be difficult to identify. We report MRI abnormalities that we believe are specific to this disorder in three patients with complete or partial MELAS syndrome. The patients all showed an unusual pattern on T2-weighted MRI with multifocal areas of hyperintense signal confined to the cortex of the cerebrum, cerebellum, and adjacent white matter. Some images suggested selective cortical involvement of deeper layers only. Deep white matter was relatively spared, distinguishing this from usual cerebrovascular disease or the edema after status epilepticus. Specificity of these findings is further suggested by a good correlation of these findings with the previously described unique postmortem brain pathology of MELAS.
 ...
PMID:Magnetic resonance imaging shows specific abnormalities in the MELAS syndrome. 206 32

Two infants who had clinical and radiographic findings consistent with Leigh syndrome were found to have deficiency of complex I (reduced nicotinamide-adenine dinucleotide--coenzyme Q reductase) activity. Significant abnormalities were found on computed tomographic scans and magnetic resonance images of the brain. Lactate and pyruvate concentrations in blood and cerebrospinal fluid were elevated, and muscle biopsy specimens showed abnormal mitochondria. These data indicate that Leigh syndrome, as well as MELAS syndrome (mitochondrial encephalopathy, myopathy, lactic acidosis, and stroke-like episodes) may result from complex I deficiency.
 ...
PMID:Complex I (reduced nicotinamide-adenine dinucleotide-coenzyme Q reductase) deficiency in two patients with probable Leigh syndrome. 210 30

The present paper reports on the clinical findings of a 34-year-old male patient with MELAS syndrome. MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis and strokelike episodes) belongs to a group of syndromes called mitochondrial encephalomyopathies that are characterized by changes of the mitochondrial respiratory chain and the histological finding of "ragged red fibers" in muscle biopsy. In our case the diagnosis was confirmed by multiple neurologic tests including muscle biopsy and biochemical analysis of the respiratory chain. The ocular findings included reversible, homonymous hemianopic visual field loss documented six years earlier, atypical retinitis pigmentosa with marked attenuation of the scotopic ERG, myopia and nuclear cataract of the right eye. An extracapsular cataract extraction with implantation of a posterior chamber lens was performed on the rigt eye, the course was unremarkable and vision improved. In dealing with patients presenting with ocular or neurologic signs indicating mitochondrial encephalopathy, the ophthalmologist should consider MELAS syndrome or any other of the mitochondrial encephalomyopathy syndromes as a possible etiology and take the necessary steps for further medical and neurologic evaluation of the patient.
 ...
PMID:[Ocular changes in MELAS syndrome]. 225 70

MELAS syndrome is a distinct clinical entity belonging to a group of mitochondrial encephalomyopathies characterized by the tetrad of myopathy, encephalopathy, lactic acidosis, and stroke-like episodes. Computed tomography (CT) and magnetic resonance (MR) findings are reviewed in a patient with MELAS. Serial CT studies demonstrated multiple "migrating" infarcts in various stages of evolution involving primarily the posterior temporal and occipital regions. MR was more sensitive than CT in demonstrating the number and extent of cortical lesions in this disease entity.
 ...
PMID:Magnetic resonance imaging in MELAS syndrome. 239 45

Increasingly numerous studies are being devoted to mitochondrial diseases, notably those which involve the neuromuscular system. Our knowledge and understanding of these diseases is progressing rapidly. We owe to Luft et al. (1962) the first description of this type of diseases. Their patient, a woman, presented with clinical symptoms suggestive of mitochondrial dysfunction, major histological abnormalities of skeletal muscle mitochondria and defective oxidative phosphorylation coupling clearly demonstrated in mitochondria isolated from muscle. This clinical, histological and biochemical triad led to the definition of mitochondrial myopathies. Subsequently, the triad was seldom encountered, and most mitochondrial myopathies were primarily defined by the presence of morphological abnormalities of muscle mitochondria. This review deals with the morphological, clinical, biochemical and genetic aspects of mitochondrial encephalomyopathies. The various morphological abnormalities of mitochondria are described. These are not specific of any particular disease. They may be present in some non-mitochondrial diseases and may be lacking in diseases due to specific defects of mitochondrial enzymes (e.g. carnitine palmityl-transferase or pyruvate dehydrogenase). The clinical classification of mitochondrial encephalomyopathies is discussed. There are two main schools of thought: the "lumpers" do not recognize specific syndromes within the spectrum of mitochondrial "cytopathies", the "splitters" try to identify specific syndromes while recognizing the existence of borderline cases. The following syndromes are described: chronic progressive external ophthalmoplegia (CPEO), Kearns-Sayre syndrome (KSS), MERRF syndrome (myoclonic epilepsy with ragged-red fibers), MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, stroke-like episodes) and Leigh and Alpers syndromes. The biochemical classification comprises five types of abnormalities: defects of transport through the mitochondrial membrane, of substrate utilization, of Krebs' cycle, of oxidative phosphorylation and of various complexes of the respiratory chain. The clinical pictures corresponding to these defects are briefly described. The genetic aspects of these diseases are especially interesting because mitochondria have their own genome coding for thirteen proteins, all of them belonging to the respiratory chain. Genetic mitochondrial diseases may result from alterations of the nuclear genome, which are transmitted by mendelian inheritance, but they may also be due to alterations of the mitochondrial genome and transmitted by non-mandelian "maternal" heredity. A few examples are discussed, including Leber's optic atrophy and MERRF syndrome. (ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Mitochondrial encephalomyopathies. 268 27


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>