Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutations in the mitochondrial tRNA(leu) (UUR) gene have been associated with diabetes mellitus and deafness. We screened for the presence of mtDNA mutations in the tRNA(leu) (UUR) gene and adjacent ND1 sequences in 12 diabetes mellitus pedigrees with a possible maternal inheritance of the disease. One patient carried a G to A substitution at nt 3243 (tRNA(leu) (UUR) gene) in heteroplasmic state. In a second pedigree a patient had an A to G substitution at nt 3397 in the ND1 gene. All maternal relatives of the proband had the 3397 substitution in homoplasmic state. This substitution was not present in 246 nonsymptomatic Caucasian controls. The 3397 substitution changes a highly conserved methionine to a valine at aa 31 and has previously been found in Alzheimer's (AD) and Parkinson's (PD) disease patients. Substitutions in the mitochondrial ND1 gene at aa 30 and 31 have associated with a number of different diseases (e.g. AD/PD, MELAS, cardiomyopathy and diabetes mellitus, LHON, Wolfram-syndrome and maternal inherited diabetes) suggesting that changes at these two codons may be associated with very diverse pathogenic processes. In a further attempt to search for mtDNA mutations outside the tRNAleu gene associated with diabetes, the whole mtDNA genome sequence was determined for two patients with maternally inherited diabetes and deafness. Except for substitutions previously reported as polymorphisms, none of the two patients showed any non-synonymous substitutions either in homoplasmic or heteroplasmic state. These results imply that the maternal inherited diabetes and deafness in these patients must result from alterations of nuclear genes and/or environmental factors.
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PMID:MtDNA mutations in maternally inherited diabetes: presence of the 3397 ND1 mutation previously associated with Alzheimer's and Parkinson's disease. 1203 16

Thirty-five mitochondrial (mt) DNAs from Spain that harbor the mutation A3243G in association with either MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) syndrome or a wide array of disease phenotypes (ranging from diabetes and deafness to a mixture of chronic progressive external ophthalmoplegic symptoms and strokelike episodes) were studied by use of high-resolution restriction fragment length polymorphism analysis and control-region sequencing. A total of 34 different haplotypes were found, indicating that all instances of the A3243G mutation are probably due to independent mutational events. Haplotypes were distributed into 13 haplogroups whose frequencies were close to those of the general Spanish population. Moreover, there was no statistically significant difference in haplogroup distribution between patients with MELAS and those with disease phenotypes other than MELAS. Overall, these data indicate that the A3243G mutation harbors all the evolutionary features expected from a severely deleterious mtDNA mutation under strong negative selection, and they reveal that European mtDNA backgrounds do not play a substantial role in modulating the mutation's phenotypic expression.
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PMID:Mitochondrial DNA haplogroups do not play a role in the variable phenotypic presentation of the A3243G mutation. 1261 63

The pathogenetic mechanism of the most extensively investigated A3243G mutated tRNALeu(UUR) gene, which causes the MELAS encephalomyopathy, maternally inherited diabetes, or chronic progressive external ophlthalmoplegia, is still unresolved, despite the numerous investigations on the topic. Previous evidences presented in published work suggested that the mitochondrial DNA harboring A3243G mutation result decreases in the rates of mitochondrial protein synthesis. To search for differences in aminoacylation of mitochondrial DNA-encoded wild-type and mutant human tRNALeu(UUR), we have expressed and purified the two kinds of tRNAsLeu(UUR), and have expressed human mitochondrial leucyl-tRNA synthetase for in vitro assays of aminoacylation of wild-type and mutant human tRNALeu(UUR). The results indicate human mitochondrial tRNALeu(UUR) gene A3243G point mutant can remarkably reduce its aminoacylation, suggesting it could be one of the mechanisms that the mutation can produce in such clinical phenotypes.
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PMID:Search for difference in aminoacylation of mitochondrial DNA-encoded wild-type and mutant human tRNALeu (UUR). 1282 90

We prenatally diagnosed MELAS syndrome in a fetus whose mother and older brother had the MELAS-specific A3243G mutation. The mutant mtDNA level of the amniotic fluid cells was not significantly different from that of the postnatal peripheral blood and hair follicle samples. The obstetrical course was uncomplicated except for transient exacerbation of the mother's diabetes, which required insulin control. At term, the infant was macrosomic, and the delivery was complicated by shoulder dystocia. MELAS syndrome in itself does not influence either the prenatal course of the mother or the fetal outcome. In contrast to the fulminating clinical course of this mother's first child, MELAS symptoms did not develop in her second child until age four, despite similar high tissue levels of mutant mtDNA. The phenotypic diversity in two offspring with similar higher levels of mutant mtDNA suggests that prenatal genetic diagnosis of cultured amniotic cells may yield results that are poor prognosticators of fetal outcome.
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PMID:Prenatal diagnosis of a fetus harboring an intermediate load of the A3243G mtDNA mutation in a maternal carrier diagnosed with MELAS syndrome. 1516 11

Mitochondrial cytopathy is a heterogeneous group of disorders with a wide range of clinical features. To evaluate the incidence and clinical heterogeneity of A3243G mitochondrial tRNA mutation in the Korean population, we evaluated patients who were clinically suggestive of having mitochondrial encephalomyopathy. Eighty-five patients were included in this study. All showed clinical features of mitochondrial encephalomyopathy and had three or more of the following clinical manifestations: (1) psychomotor regression, (2) hyperlacticacidemia, (3) recurrent stoke-like episodes, (4) idiopathic cardiomyopathy, (5) sensoryneural hearing loss, (6) diabetes mellitus, (7) myopathy, (8) renal disease and (9) relatives with known mitochondrial disease. The patients were clinically classified as MELAS, MERRF, Leigh syndrome, Kearns-Sayre syndrome, chronic progressive external ophthalmoplegia and uncertain. Of the 85 patients, 19 had the A3243G mutation (22.3%). Thirty-one patients showed typical clinical characteristics of MELAS. Fourteen of those 31 patients had A3243G mutation (45.1%). Four patients harboring A3243G mutations showed atypical and heterogeneous clinical features, unlike MELAS. This study revealed the frequent occurrence of A3243G mutation in Korean patients with mitochondrial disorders and their clinical features can be heterogeneous. It will be helpful to screen the presence of A3243G mutation for the genetic diagnosis of mitochondrial encephalomyopathy in Korea.
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PMID:Clinical features of A3243G mitochondrial tRNA mutation. 1535 Oct 82

The availability of monoclonal antibodies (mAbs) against the proteins of the oxidative phosphorylation chain (OXPHOS) and other mitochondrial components facilitates the analysis and ultimately the diagnosis of mitochondrially related diseases. mAbs against each of the five complexes and pyruvate dehydrogenase (PDH) are the basis of a rapid and simple immunocytochemical approach [Hanson, B.J., Capaldi, R.A., Marusich, M.F. and Sherwood, S.W., J. Histochem. Cytochem. 50 (2002) 1281-1288]. This approach can be used to detect if complexes have altered assembly in mitochondrial disease due to mutations in nuclear encoded genes, such as in Leigh's disease, or in mitochondrially encoded genes, e.g., MELAS. Other mAbs have recently been obtained that can immunocapture each of the five OXPHOS complexes, PDH and the adenine nucleotide translocase (ANT) from very small amounts of tissue such as that obtained from cell culture or needle biopsies from patients. When adapted to a 96-well plate format, these mAbs allow measurement of the specific activity of each of the mitochondrial components individually and analysis of their subunit composition and state of posttranslational modification. The immunocapture protocol should be useful not only in the analysis of genetic mitochondrial diseases but also in evaluating and ultimately diagnosing late-onset mitochondrial disorders including Parkinson's disease, Alzheimer's disease, and late-onset diabetes, which are thought to result from accumulated oxidative damage to mitochondrial proteins such as the OXPHOS chain.
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PMID:Focused proteomics: towards a high throughput monoclonal antibody-based resolution of proteins for diagnosis of mitochondrial diseases. 1557 53

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

Maternal diabetes associated with neural deafness is designated as MIDD (maternal inherited diabetes and deafness); it is linked to a A3243G tRNA leucine gene mutation. The disease course is progressive and involvement of other systems is frequent. In most cases, macular pattern dystrophy is present. Muscular lesions are characteristic of mitochondrial myopathies. Mitochondrial abnormalities have also been observed in pancreas, heart, kidney, smooth muscle of the digestive tract with variable heteroplasmy levels. MIDD may present as a single syndrome or is part of MELAS or Kearns-Sayre syndrome.
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PMID:[Diabetes and mitochondrial cytopathies: pathological studies]. 1632 55

Mitochondrial respiratory function in a patient with maternally inherited type 2 diabetes mellitus and hypertrophic cardiomyopathy associated with heteroplasmic mitochondrial DNA (mtDNA) C3310T mutation, which replaces the second amino acid of NADH dehydrogenase 1 (ND1) from a hydrophobic Proline to a hydrophilic Serine, was investigated. Mitochondrial respiratory function solely due to mtDNA C3310T mutation was investigated in cybrid system by the fusion of mtDNA-deleted (rho(0)) HeLa cells and exogenous mtDNA either from the proband or from controls. Total oxygen consumption of the proband cybrid cells was significantly decreased compared with those of controls (2.468+/-0.475 versus 2.871+/-0.484 micromol/h/10(7) cells, p=0.0392). Mitochondrial respiratory chain complex I activity of the proband cybrid cells was also significantly decreased compared with those of controls (0.191+/-0.080 versus 0.288+/-0.113 micromol/h/mg protein, p=0.0223). Furthermore, ATP content in the proband cybrid cells was also significantly decreased compared with those in controls (1.119+/-0.344 versus 1.419+/-0.378 pmol/10(5) cells, p=0.044). The present study indicates that mtDNA C3310T mutation may be a pathogenic mutation of maternally inherited type 2 diabetes mellitus and hypertrophic cardiomyopathy in the proband and the family.
Diabetes Res Clin Pract 2006 Nov
PMID:Mitochondrial complex I activity is significantly decreased in a patient with maternally inherited type 2 diabetes mellitus and hypertrophic cardiomyopathy associated with mitochondrial DNA C3310T mutation: a cybrid study. 1682 17

Ocular complications are common in the mitochondrial cytopathies and include optic atrophy and retinal degeneration. We retrospectively reviewed 80 patients with nonsyndromic mitochondrial cytopathies (ie, not Kearns-Sayre syndrome, myoclonus epilepsy associated with ragged red fibers [MERRF], mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes [MELAS], neuropathy ataxia and retinitis pigmentosa, Leigh disease, maternally inherited diabetes and deafness, and myoneurogastrointestinal disorder and encephalopathy) and found 10 cases of optic nerve hypoplasia. Optic nerve hypoplasia occurs in at least 12% of patients with nonsyndromic mitochondrial cytopathies. Although the exact pathogenesis of optic nerve hypoplasia in the context of mitochondrial cytopathy is unknown, we postulate that it is the result of excessive apoptosis during embryonic ganglion cell and/or axonal development from abnormal mitochondrial function and cellular energy metabolism.
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PMID:Association of optic nerve hypoplasia with mitochondrial cytopathies. 1709 61


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