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 17-year old girl presented with recurrent seizures, strokes, fatigue, vomiting, cerebellar ataxia, dementia and hypertrichosis. Further examinations showed jerking left-sided arm reflexes, partial internal deafness and myopathy. CT and MR of the skull revealed radiolucencies within the cerebral matter of the cortex and the medulla. Laboratory tests showed increased levels of lactate and pyruvate in serum and cerebro-spinal fluid. Microscopic examination of muscular tissue showed "ragged red fibers". Electron microscopy yielded crystal inclusions in mitochondria. The symptoms represented the complete picture of the so-called MELAS/MERRF-complex, which can be easily misdiagnosed as strokes and seizures of unknown cause.
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PMID:[Stroke, epilepsy and abdominal pain as leading symptoms in a case of mitochondrial encephalomyopathy]. 844 77

The mitochondrial DNA A3243G transition is a fairly common mutation which often associates with a MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) phenotype, however, a broad variety in the associated clinical picture has also been described. The patient reported here developed a generalized seizure at age 12, which was followed by bilateral hearing loss and occasional fatigue. The maternal inheritance pattern of hearing loss pointed to a possible mitochondrial origin, which was confirmed by molecular analysis of the mitochondrial DNA, revealing a heteroplasmic A3243G transition. Interestingly, muscle biopsy showed ragged-red fibers in the proband, which is unusual in the deafness-associated forms of this mitochondrial disorder. In addition to hearing impairment in four generations of the family, fatal cerebral embolization in the mother and fatal heart attack in the maternal grandmother (both at age 33) also occurred. On the contrary, diabetes, which usually accompanies the hearing loss variant, was specifically absent in all generations. The unusual manifestations associated with this mutation somewhat differentiate this family from the already known variants.
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PMID:Maternally inherited deafness and unusual phenotypic manifestations associated with A3243G mitochondrial DNA mutation. 1599 51

MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) is commonly associated with the A3243G mitochondrial DNA (mtDNA) mutation encoding the transfer RNA of leucine (UUR) (tRNA (Leu(UUR))). The pathogenetic mechanisms of this mutation are not completely understood. Neuronal functions are particularly vulnerable to alterations in oxidative phosphorylation, which may affect the function of the neurotransmitter glutamate, leading to excitotoxicity. In order to investigate the possible effects of A3243G upon glutamate homeostasis, we assessed glutamate uptake in osteosarcoma-derived cytoplasmic hybrids (cybrids) expressing high levels of this mutation. High-affinity Na(+)-dependent glutamate uptake was assessed as radioactive [(3)H]-glutamate influx mediated by specific excitatory amino acid transporters (EAATs). The maximal rate (V(max)) of Na(+)-dependent glutamate uptake was significantly reduced in all the mutant clones. Although the defect did not relate to either the mutant load or magnitude of oxidative phosphorylation defect, we found an inverse relationship between A3243G mutation load and mitochondrial ATP synthesis, without any evidence of increased cellular or mitochondrial free radical production in these A3243G clones. These data suggest that a defect of glutamate transport in MELAS neurons may be due to decreased energy production and might be involved in mediating the pathogenic effects of the A3243G mtDNA mutation.
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PMID:MELAS mitochondrial DNA mutation A3243G reduces glutamate transport in cybrids cell lines. 1845 61

The 3243A>G mutation of mtDNA usually is associated with MELAS syndrome. Here we report a patient with the 3243A>G mutation presenting only recurrent muscle fatigue and elevated levels of serum creatine kinase (CK). The mother of the proband was referred to us for type 2 diabetes mellitus, muscle pain and sensorineural hearing loss. The percentage of mutation load in different tissues was similar in both subjects, except in the urinary epithelium. The mutation load in the son's urinary epithelial cells (UEC) was consistently higher (nearly 50%) than in his muscle (nearly 20%). We conclude that a correlation between the proportion of the UEC mutation load and the severity of the disease was lacking in this pedigree. The use of UEC as the tissue of choice in the noninvasive diagnosis of the 3243A>G mutation offers a very attractive alternative to muscle biopsy. Finally, our data expand the clinical spectrum of the 3243A>G mutation.
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PMID:A case of 3243A>G mutation in mtDNA presenting as apparently idiopathic hyperCKemia. 2446 40

Background: Mitochondrial diseases are caused by dysfunctions in mitochondrial metabolic pathways. MELAS syndrome is one of the most frequent mitochondrial disorders; it is characterized by encephalopathy, myopathy, lactic acidosis, and stroke-like episodes. Typically, it is associated with a point mutation with an adenine-to-guanine transition at position 3243 of the mitochondrial DNA (mtDNA; m.3243A>G) in the mitochondrially encoded tRNA leucine 1 (MT-TL1) gene. Other point mutations are possible and the association with polyglandular autoimmune syndrome type 2 has not yet been described. Case presentation: We present the case of a 25-year-old female patient with dysexecutive syndrome, muscular fatigue, and continuous headache. Half a year ago, she fought an infection-triggered Addison crisis. As the disease progressed, she had two epileptic seizures and stroke-like episodes with hemiparesis on the right side. Cerebral magnetic resonance imaging showed a substance defect of the parieto-occipital left side exceeding the vascular territories with a lactate peak. The lactate ischemia test was clearly positive, and a muscle biopsy showed single cytochrome c oxidase-negative muscle fibers. Genetic testing of blood mtDNA revealed a heteroplasmic base exchange mutation in the mitochondrially encoded NADH:ubiquinone oxidoreductase core subunit 4 (MT-ND4) gene (m.12015T>C; p.Leu419Pro; heteroplasmy level in blood 12%, in muscle tissue: 15%). The patient suffered from comorbid autoimmune polyglandular syndrome type 2 with Hashimoto's thyroiditis, Addison's disease, and autoimmune gastritis. In addition, we found increased anti-glutamic acid decarboxylase 65, anti-partial cell, anti-intrinsic factor, and anti-nuclear antibodies. Conclusion: We present an atypical case of MELAS syndrome with predominant symptoms of a dysexecutive syndrome, two stroke-like episodes, and fast-onset fatigue. The symptoms were associated with a not yet described base and aminoacid exchange mutation in the MT-ND4 gene (m.12015T>C to p.Leu419Pro). The resulting changed protein complex in our patient is part of the respiratory chain multicomplex I and might be the reason for the mitochondriopathy. However, different simulations for pathogenetic relevance are contradictory and rather speak for a benign variant. To our knowledge this case report is the first reporting MELAS syndrome with comorbid polyglandular autoimmune syndrome type 2. Screening for autoimmune alterations in those patients is important to prevent damage to end organs.
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PMID:New Variant of MELAS Syndrome With Executive Dysfunction, Heteroplasmic Point Mutation in the MT-ND4 Gene (m.12015T>C; p.Leu419Pro) and Comorbid Polyglandular Autoimmune Syndrome Type 2. 3129 67