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

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.
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PMID:[Mitochondrial encephalopathy affecting only the central nervous system]. 196 61

Mitochondrial myopathy, encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is one of the mitochondrial encephalomyopathies that has distinct clinical features including stroke-like episodes with migraine-like headache, nausea, vomiting, encephalopathy and lactic acidosis. We report a 27-year-old woman who presented with partial seizure, stroke-like episodes including hemiparesis, hemianopia and hemihypethesia, sensorineural hearing loss, migraine-like headache, and lactic acidosis. Brain computed tomographic scan showed encephalomalacia in the right parieto-occipital area and recent hypodensity in the left temporoparieto-occipital area with cortical atrophy. Muscle biopsy revealed ragged-red fibers and paracrystaline inclusions in the mitochondria. Genetic study revealed an A to G point mutation at nucleotide position (np) 3243 of mitochondrial DNA. External ophthalmoplegia and ptosis were also found during two exaggerated episodes in this patient. Therefore, the overlapping syndrome of chronic progressive external ophthalmoplegia in the MELAS syndrome is considered in this case. Furthermore, we also found carnitine deficiency in this patient and she was responsive well to steroid therapy. Muscle biopsy also revealed excessive lipid droplets deposits. Therefore, the carnitine deficiency may occur in MELAS syndrome with the A to G point mutation at np 3243. We recommend the steroid or carnitine supplement therapy be applied to the MELAS syndrome with carnitine deficiency.
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PMID:CPEO and carnitine deficiency overlapping in MELAS syndrome. 748 81

Two MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) patients with diabetes mellitus (DM), and their family members are described clinically and genetically. The probands have the following features in common; normal early development, short stature, deterioration of intellectual ability, convulsions, cardiac conduction defect, sensorineural hearing loss, cortical blindness, and hemiparesis. Biochemical tests showed high levels of lactate and pyruvate in the blood and cerebrospinal fluid. Muscle biopsy showed ragged-red fibers. Molecular genetic analysis of both patients revealed that they had an A-to-G substitution at nucleotide position 3243 of the mitochondrial DNA in a heteroplasmic fashion. From these clinical and molecular genetic data they were diagnosed as having MELAS. In addition, fasting blood glucose levels were also high and they were diagnosed as having insulin-dependent DM. Some of the maternal family members in both cases also had insulin-dependent DM and several clinical symptoms of MELAS. DM and clinical features of MELAS were transmitted exclusively in the maternal line. In these cases, DM and MELAS might be a clinical manifestation of the same metabolic defect.
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PMID:Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and diabetes mellitus: molecular genetic analysis and family study. 844 2

Mitochondrial DNA (mtDNA) mutation associated with sensorineural hearing loss (SNHL) has previously been described in MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) and in aminoglycoside-induced deafness. The authors of this study report three cases of SNHL associated with mtDNA mutation (3243A-->G). They examined the clinical features of this type of SNHL by audiologic studies and examined the mtDNA mutation by the polymerase chain reaction technique. In the three cases described, the SNHL had an adult onset and was bilateral and symmetrical. All patients had adult-onset diabetes mellitus. Audiologic studies revealed that the SNHL in all patients derived from the cochlea rather than from retrocochlear sites. It is presumed that mtDNA mutation results in mitochondrial dysfunction in cochlear tissues (i.e., hair cells and stria vascularis) and in neurons of the auditory pathway. Genetic analysis of mtDNA offers new insight into the diagnosis and treatment of SNHL.
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PMID:Bilateral sensorineural hearing loss associated with the point mutation in mitochondrial genome. 854 26

A mitochondrial A 3243 G mutation in the tRNA(Leu(UUR)) gene was first described as a common cause of MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like syndrome). This same mutation is also the cause of a totally different disorder, a subtype of diabetes mellitus which is inherited maternally and often associated with sensorineural hearing loss. In this paper, we report on a Japanese boy with A 3243 G who developed a previously undescribed combination of symptoms, nephropathy and growth hormone deficiency. The patient first presented with short stature and moderate mental retardation. Growth hormone (GH) provocation tests showed deficient growth hormone secretion. During the course of follow up, he presented with progressive nephropathy followed by the development of diabetes mellitus. The results of laboratory tests and renal biopsy were against incidental association of known types of nephropathy. On PCR-RFLP analysis, the percentage of mutated mtDNA was higher in the renal biopsy specimen than 12 peripheral blood leucocytes. Our case suggests that mitochondrial diseases should be taken into account when there is nephropathy of unknown cause. In addition, the presence of growth hormone deficiency may account for part of the mechanism leading to short stature commonly seen in these patients.
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PMID:Nephropathy and growth hormone deficiency in a patient with mitochondrial tRNA(Leu(UUR)) mutation. 881 55

A mitochondrial tRNALeu(UUR) mutation at nucleotide 3,243 is known to be found in most patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) and has also been identified in several families with maternally inherited diabetes mellitus and hearing loss. We report here audiologic features in patients with hearing loss associated with the mutation. Four patients without and five with MELAS were studied. Most of the patients had bilateral progressive sensorineural hearing loss. The most common shape of the audiogram was sloping, while cases in the advanced stages had flat audiograms. Speech discrimination scores were generally poor and did not parallel the degree of hearing loss. The present study suggests that the lesion for hearing loss could include both cochlear and retrocochlear involvement, but does not demonstrate a significant difference in the audiologic findings between patients with and without MELAS.
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PMID:Audiologic findings in patients with a point mutation at nucleotide 3,243 of mitochondrial DNA. 910 27

A case of sensorineural hearing loss (SNHL) in MELAS syndrome, a variety of mitochondrial cytopathy, is presented. Mitochondrial cytopathies have gone almost unreported in the otolaryngology literature, despite evidence from a recent review that about 60 per cent of such patients suffer from SNHL (Gold and Rapin, 1994). The same review revealed that only one of 117 case reports in the period 1984-1993 contained an audiogram (Swift and Singh, 1988), and none presented sequential audiograms. However, audiometry has since been published on 23 members of a family with a mitochondrial point mutation causing only sensorineural hearing loss with no other symptoms (Vernham et al., 1994). We present a case of mitochondrial cytopathy three years after diagnosis with two sequential audiograms.
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PMID:Sensorineural hearing loss in MELAS syndrome. 915 69

There have been few studies investigating the mechanism and nature of the hearing loss that occurs in the mitochondrial disorders. We studied 18 patients with the MELAS A3243G point mutation from four different kindreds. Pure tone audiometry, speech discrimination testing, acoustic reflexes, tympanometry, and brain stem auditory evoked responses were performed to localize the site of pathology in the auditory pathways. In 12 patients, we performed electrocochleography and otoacoustic emissions to assess cochlear involvement. Neuroimaging and promontory nerve stimulation were performed to exclude retrocochlear pathology. Audiological testing confirmed sensorineural hearing loss in 14 of the 18 patients studied; hearing loss was usually gradual in onset, was symmetrical, and initially affected the higher frequencies. In some patients, there were features that distinguished the hearing loss from presbyacusis, including a young age at onset, asymmetrical involvement, stepwise progression, and partial recovery. We treated one patient who had profound bilateral hearing loss with cochlear implantation; this restored good functional hearing. Hearing loss in MELAS syndrome appears to be due to dysfunction of the cochlea, probably resulting from metabolic failure of the stria vascularis and outer hair cells. Cochlear implantation is a therapeutic option worth considering in those patients who become deaf.
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PMID:Cochlear origin of hearing loss in MELAS syndrome. 950 52

A mitochondrial tRNA mutation at nucleotide 3,243 is known to be found in most patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes). We report a 30 year-old female patient of MELAS, diagnosed 5 years ago, who presented herself to our ENT outpatient department because of her bilateral tinnitus and progressive hearing impairment since 4 years ago. Two sequential pure tone audiograms showed bilateral symmetrical progressive sensorineural hearing loss, especially in the high frequency area in 1993 and 1996. The pure tone average was R-45 dB, L-47 dB in 1993 and R-62 dB, L-67 dB in 1996. Hearing loss is an important feature in MELAS syndrome and reported to be seen in about 30% of patients. It is often the first clinical symptom, too. In any case, mitochondrial cytopathies need to be considered by the otologist in forming a diagnosis of sensorineural hearing loss (SNHL), particularly in cases, which present adult-onset progressive hearing loss and neurologic symptoms before 50 years of age.
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PMID:Sensorineural hearing loss in MELAS syndrome--case report. 978 Jun 3

MELAS syndrome (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) is a rare congenital disorder of mitochondrial DNA (mt-DNA). Patients with this syndrome may present to the otolaryngologist with sensorineural hearing loss (SNHL) that is genetic in origin. Mitochondrial cytopathies can present with a variety of symptoms, but they occasionally present with SNHL as their first manifestation. Two cases of MELAS patients who responded well to cochlear implantation are presented. A review of the literature is also carried out focusing mainly on diagnosis, anesthetic considerations and management of these patients.
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PMID:Cochlear implantation in patients with MELAS syndrome. 1584 11


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