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)

An important feature of the mitochondrial genom is the occurrence of heteroplasmy and the possibility for transmission to the offspring of various proportions of wild-type and mutated mtDNA. We have investigated the proportion of the tRNALys A8344G mutation, the tRNALeu(UUR) A3243G mutation, and the ATPase 6 T8993G mutation in patients with MERRF, MELAS, and Leigh's syndrome and their maternal relatives. The level of mutated mtDNA in the offspring of carriers of the tRNALys mutation is correlated to the level in lymphocytes in the mother and seems to be transmitted by an essentially random mechanism where only a few mtDNA copies are founders of the mitochondrial genom in the offspring and the probability that the mutation is not transmitted to the offspring is high when the mothers carriers predominantly wild-type mtDNA. However, we found age-related differences in the distribution of mutated mtDNA in carriers of the tRNALys and tRNALeu mutations, which have to be considered before levels of mutated mtDNA are used for prediction of prognosis and transmission of a disorder.
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PMID:Inheritance and expression of mitochondrial DNA point mutations. 759 16

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