Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0029089 (ophthalmoplegia)
 3,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The investigation of pathogenic mitochondrial DNA (mtDNA) mutations has revealed a complex relation between patient genotype and phenotype. For unknown reasons, some mtDNA mutations produce specific clinical manifestations such as chronic progressive external ophthalmoplegia; myoclonic epilepsy and ragged-red fiber disease (MERRF); and mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). To enhance our understanding of the association between genotype and phenotype, we investigated a patient with mitochondrial encephalomyopathy and severe cerebral calcifications for a mtDNA mutation. There was a deletion of one of three T:A nucleotide pairs in the tRNALeu(UUR) gene of the mtDNA involving positions 3271 to 3273. Pedigree analysis suggested that this mutation may have occurred spontaneously in the proband. This analysis represents the smallest mtDNA deletion observed to date and is the first deletion identified within a mitochondrial tRNA. This observation emphasizes the importance of delineating the precise mutation responsible for an oxidative phosphorylation disease for patient diagnosis as well as for genetic counseling of maternal lineage relatives.
 ...
PMID:Mitochondrial encephalomyopathy associated with a single nucleotide pair deletion in the mitochondrial tRNALeu(UUR) gene. 785 27

We report a patient with mitochondrial encephalomyopathy presenting parkinsonism, as well as her brother who had ataxia but not parkinsonism. Both patients had myopathy, deafness, and insulin-dependent diabetes mellitus. The proband was a 55-year-old woman, who has developed progressive difficulty in walking and slowness of movement since 53 years of age, becoming bed-ridden at 55. Neurological examination revealed mental impairment, a masked face, Myerson's sign, vertical supranuclear ophthalmoplegia, and severe sensorineural deafness, hypokinesia, rigidospasticity, and weakness of the extremities. But tremor and cerebellar ataxia were absent. Her 48-year-old brother gradually developed weakness of the lower extremities and drunken gait over a few years. On neurologic examination, vertical supranuclear ophthalmoplegia, moderate sensorineural deafness, and cerebellar ataxia were present, but parkinsonism was absent. Three other siblings were reported to have died in early childhood. Cranial MR imaging showed cerebral atrophy and mild atrophy of the cerebellar vermis as well as mild periventricular hyperintensities in T2-weighted images in both patients. However, no infarcts were seen. Laboratory investigations revealed slightly elevated lactate and pyruvate levels in the proband and elevation of pyruvate in her brother. A biopsy specimen obtained from the quadriceps muscle showed ragged-red fibers with modified Gomori trichrome staining, and a decrease of complex I+III and complex II+III activity in the proband. Mitochondrial DNA (mtDNA) analysis using the polymerase chain reaction and restriction enzyme Apa I showed a point mutation in the tRNA(Leu)(UUR)) gene (an A to G transition at nucleotide 3243) in both patients.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:[Mitochondrial encephalomyopathy associated with parkinsonism and a point mutation in the mitochondrial tRNA(Leu)(UUR)) gene]. 802 31

We have investigated nine children with infantile onset of mitochondrial myopathy and two adults with myoclonus epilepsy and ragged-red fibers (MERRF) and chronic progressive external ophthalmoplegia (CPEO), respectively. These patients lacked any of the previously known pathogenic tRNA mutations. Southern blot analysis of muscle mtDNA revealed no deletions. The tRNA genes of muscle mtDNA were sequenced. Restriction enzyme analysis of PCR fragments was performed to verify the presence of the mutations identified by automatic sequencing. Several tRNA mutations were found, but they were all homoplasmic. Furthermore, the mutations were either present in controls or did not change nucleotides conserved between species. This strongly suggests that none of the tRNA mutations identified in the 11 patients with mitochondrial encephalomyopathy was pathogenic. It can thus be concluded that mitochondrial tRNA mutations and mtDNA deletions probably are an infrequent cause of mitochondrial disorders in infants. Patients with MERRF and CPEO may lack both pathogenic point mutations of tRNA genes and deletions of mtDNA.
 ...
PMID:Automatic sequencing of mitochondrial tRNA genes in patients with mitochondrial encephalomyopathy. 815 39

We identified two patients with pathogenic single nucleotide changes in two different mitochondrial tRNA genes: the first mutation in the tRNA(Asn) gene, and the ninth known mutation in the tRNA(Leu(UUR)) gene. The mutation in tRNA(Asn) was associated with isolated ophthalmoplegia, whereas the mutation in tRNA(Leu(UUR)) caused a neurological syndrome resembling MERRF (myoclonus epilepsy and ragged-red fibers) plus optic neuropathy, retinopathy, and diabetes. Both mutations were heteroplasmic, with higher percentages of mutant mtDNA in affected tissues, and undetectable levels in maternal relatives. Analysis of single muscle fibers indicated that morphological and biochemical alterations appeared only when the proportions of mutant mtDNA exceeded 90% of the total cellular mtDNA pool. The high incidence of mutations in the tRNA(Leu(UUR)) gene suggests that this region is an "etiologic hot spot" in mitochondrial disease.
 ...
PMID:Two novel pathogenic mitochondrial DNA mutations affecting organelle number and protein synthesis. Is the tRNA(Leu(UUR)) gene an etiologic hot spot? 825 46

It has been clarified at the molecular and genetic levels that mitochondrial DNA (mt DNA) and/or nuclear DNA mutations are the cause of a group of diseases called mitochondrial cytopathies or mitochondrial myopathies. We review: (1) the characteristics of mtDNA and its inheritance, (2) the mtDNA deletions in Kearns-Sayre syndrome and chronic progressive external ophthalmoplegia, (3) the point mutations in mtDNA tRNA(Leu(UUR)) gene at positions 3,243 and 3,271 in mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), (4) the mtDNA deletions and point mutations in patients with dilated or hypertrophic cardiomyopathy, and (5) the mtDNA deletions or point mutation in three pedigrees with maternally transmitted non-insulin-dependent diabetes mellitus.
 ...
PMID:[Molecular biology of mitochondrial DNA and mutations in mitochondrial cytopathy]. 832 Aug 24

We describe a 15-year-old boy with full-blown mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and chronic progressive external ophthalmoplegia (CPEO). He presented with visual disturbance, hearing impairment, continuous partial epilepsy on the right aspect of the face, and right hemiparesis since the age of 13. Four months later, he experienced another strokelike episode with continuous partial epilepsy on the left hand. Serial computed tomographic scans revealed bilateral parieto-occipital hypodense lesions with gyral enhancement and an additional low-density lesion in the right frontal area 4 months later, respectively. Results of laboratory examinations disclosed lactic acidosis and mitochondrial myopathy with many ragged-red fibers. To identify the defective gene in mitochondrial DNA, a simple molecular test was performed by using restriction endonuclease Apa I. A transition from A to G was found at nucleotide position 3243 of the tRNA(Leu) gene. Interestingly, the patient also had marked external ophthalmoplegia and ptosis commonly found in patients with CPEO. Therefore, we suggest that ophthalmoplegia also occurs in the MELAS syndrome.
 ...
PMID:Ophthalmologic manifestations in MELAS syndrome. 836 52

We describe a two-generation family with combined clinical features of myoclonic epilepsy, progressive external ophthalmoplegia (PEO), proximal myopathy, pigmentary retinopathy, progressive deafness, basal ganglia calcification, and ragged-red fibers in a muscle biopsy specimen. One family member died unexpectedly at age 22 years. The molecular tests revealed an A-to-G transition at nucleotide position 3243 of the mitochondrial tRNA(Leu(UUR)) gene. No one in this family had stroke-like episodes. Although the propositus (a 28-year-old woman) had a significant number of white hairs, the percentage of mutant mtDNA in white-hair roots was not different from that in the colored-hair roots. Our findings suggest that the 3243 mutation can be associated with mixed clinical features of myoclonic epilepsy with ragged-red fibers (MERRF) and PEO and that a preferential increase in the levels of the mutant mtDNA is not related to graying of hair, and hence to the hypothesized production of premature aging of cells.
 ...
PMID:A MERRF/PEO overlap syndrome associated with the mitochondrial DNA 3243 mutation. 862 77

We report an Italian family with maternally inherited encephalomyopathy including progressive external ophthalmoplegia, seizures, and neurophysiological evidence of brainstem dysfunction. Mitochondrial DNA analysis showed a heteroplasmic point mutation at position 5814 in the tRNA gene for cysteine (A5814G), previously reported in a 5-year-old girl of Portuguese origin. The mutation was very abundant (> 95%) in both muscle and blood from the proposita and was present in lower proportions (average 85 +/- 6%) in blood from three less severely affected maternal relatives. This observation confirms pathogenicity for the A5814G mutation.
 ...
PMID:Mitochondrial tRNA(Cys) gene mutation (A5814G): a second family with mitochondrial encephalopathy. 918 78

We performed a comparative analysis of the clinical, morphological and molecular characteristics of 62 patients affected with progressive external ophthalmoplegia with ragged-red fibres in muscle. Twenty-seven patients had only muscular disease, and 35 had a multisystemic disease with neurological, cardiac, sensory, or endocrine symptoms. Quantitation of mitochondrial accumulation and numbering of cytochrome c oxidase deficient muscle fibres were done in 43 patients. Muscle mitochondrial DNA deletions were detected, quantitated and localised by Southern Blot analysis. Point mutations were screened in five mitochondrial DNA transfer RNA genes by denaturing gradient gel electrophoresis technique. This study further emphasized the relationships between progressive external ophthalmoplegia and mitochondrial DNA mutations that were present in 46/62 patients (40 deletions, 4 h point mutations in the tRNA leucine gene and 2 further families with maternal inheritance but no mutation identified to-date). Family history was positive in 12 patients: 4 with a maternally inherited disease (2 of whom had an identified mitochondrial DNA mutation), and 4 with an autosomal dominant inherited disease, none of which was associated with multiple mitochondrial DNA deletions. Interestingly, 2 of our patients with an identified mitochondrial DNA mutation appeared as sporadic cases. No morphological or molecular parameters was correlated with the tissular extension of the disease. However, mitochondrial DNA deletions were significantly associated with ocular symptoms which had an earlier onset and were more severe. Clinical features of the patients with a multisystemic disease and a mitochondrial DNA deletion were essentially related to Kearns-Sayre syndrome. In particular, a cardiac conduction defect was present in 12 patients out of 18 with a multisystemic disease associated with a mitochondrial DNA deletion; it was never encountered in 17 patients with a multisystemic disease but no mitochondrial DNA deletion.
 ...
PMID:[Progressive external ophthalmoplegia of mitochondrial origin: contribution of morphological and molecular studies]. 929 56

Determination of the total mtDNA sequence of a 42 year-old female with chronic progressive external ophthalmoplegia (CPEO) revealed a heteroplasmic G-to-A transition at nt. 5877 in the tRNA-Tyr gene and a homoplasmic T-to-C transition in the tRNA-Gln gene at 4343. The former mutation was located in a highly conserved nucleotide in the DHU loop. This mutation by restriction enzyme analysis using Ddel was observed only in the blood of her two asymptomatic children and her mother. The tRNA-Gln mutation in the T psi C loop was found in a few controls and in all of her maternal relatives. The cybrid clones including tRNA-Tyr mutation showed decreased oxygen utilization and fragility against oxygen stress. This tRNA-Tyr mutation is tightly associated with CPEO.
 ...
PMID:[A mitochondrial DNA mutation in the heteroplasmic tRNA-Tyr gene associated with chronic progressive external ophthalmoplegia--clinical and molecular biological study]. 943 48


<< Previous 1 2 3 4 5 6 7 Next >>