Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An 8-year-old girl with progressive ataxia and bulbar palsy showed diffuse white-matter lesions in the occipital to parietal lobes on magnetic resonance imaging. Since she had slightly elevated lactate in the cerebrospinal fluid, a muscle biopsy was done which revealed scattered ragged-red fibres and focal cytochrome c oxidase deficiency. Southern blot and polymerase-chain-reaction analyses revealed a large-scale mitochondrial DNA deletion, which was 6990 base-pairs in length with 6 base-pair (-TCATCG-) direct repeats at the junctions. Mitochondrial DNA mutation should be considered as one of the candidate causes for diffuse leukodystrophy in children.
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PMID:Diffuse leukodystrophy with a large-scale mitochondrial DNA deletion. 791 Aug 87

The toxicology of narasin has been extensively investigated in several species of laboratory animals. Acute median lethal po doses varied considerably between species (> 10 to 40.8 mg/kg). Animals of various species given acutely toxic doses of narasin manifested similar clinical signs of toxicity, including anorexia, hypoactivity, leg weakness, ataxia, depression and diarrhea. Clinical effects were usually delayed 1 to several days, depending on the dose, and some were reversible even with continued narasin administration. In repeated dose toxicity studies, narasin dosages have been demonstrated at which animals could be exposed daily for long periods of time without producing harmful effects. The no-observed effect levels (NOELs) by the dietary route were 60 ppm in mice and 15 ppm in rats after 3 mo of dosing and 15 ppm in rats after 1 y. In dogs, NOELs were 1 mg/kg body weight after 3 mo and 0.5 mg/kg body weight after 1 y of dosing. In breeding animals, narasin did not affect reproductive performance through 4 generations and was not teratogenic. Two-y chronic bioassays in 2 rodent species showed that narasin did not produce cumulative toxicity or carcinogenicity. In genetic toxicity tests narasin was not mutagenic to bacterial or mammalian cells and did not induce DNA repair or sister chromatid exchange. Narasin neither caused dermal toxicity nor skin sensitization, but was a severe eye irritant in rabbits. In dogs, local irritation and systemic toxicity occurred following repeated inhalation exposure to narasin aerosol concentrations greater than 0.114 mg/M3 of air.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The comparative toxicology of narasin in laboratory animals. 797 39

We review the main features of human mitochondrial function and structure, and in particular mitochondrial transcription, translation, and replication cycles. Furthermore, some pecularities such as mitochondria's high polymorphism, the existence of mitochondrial pseudogenes, and the various considerations to take into account when studying mitochondrial diseases will also be mentioned. Mitochondrial syndromes mostly affecting the nervous system have, during the past few years, been associated with mitochondrial DNA (mt DNA) alterations such as deletions, duplications, mutations and depletions. We suggest a possible classification of mitochondrial diseases according to the kind of mt DNA mutations: structural mitochondrial gene mutation as in LHON (Leber's Hereditary Optic Neuropathy) and NARP (Neurogenic muscle weakness, Ataxia and Retinitis Pigmentosa) as well as some cases of Leigh's syndrome; transfer RNA and ribosomal RNA mitochondrial gene mutation as in MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Strokelike Episodes) or MERRF (Myoclonic Epilepsy with Ragged Red Fibers) or deafness with aminoglycoside; structural with transfer RNA mitochondrial gene mutations as observed in large-scale deletions or duplications in Kearns-Sayre syndrome, Pearson's syndrome, diabetes mellitus with deafness, and CPEO (Chronic Progressive External Ophtalmoplegia). Depletions of the mt DNA may also be classified in this category. Even though mutations are generally maternally inherited, most of the deletions are sporadic. However, multiple deletions or depletions may be transmitted in a mendelan trait which suggests that nuclear gene products play a primary role in these processes. The relationship between a mutation and a particular phenotype is far from being fully understood. Gene dosage and energic threshold, which are tissue-specific, appear to be the best indicators. However, the recessive or dominant behavior of both the wild type or the mutated genome appears to play a significant role, which can be verified with in vitro studies.
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PMID:Mitochondrial DNA alterations and genetic diseases: a review. 799 80

Two half-brothers and their mother had symptomatic pyruvate dehydrogenase complex deficiency. The infants had severe congenital lactic acidosis, seizures, and apneic spells and died at the ages 3 and 4 months. The mother was less symptomatic with mental retardation, truncal ataxia, and dysarthria. The residual pyruvate dehydrogenase activities in cultured skin fibroblasts from the 2 infants and their mother were 7, 15, and 10% of control values. Immunoblot analysis showed negligible amounts of E1 alpha and E1 beta subunits of the complex. Northern blot analysis for the E1 alpha subunit showed normal results. In the 2 sons, complementary DNA sequence analysis revealed a cytosine to thymine mutation in exon 4, resulting in a change of arginine 127 to tryptophan in the E1 alpha subunit. Restriction enzyme analysis of the polymerase chain reaction product representing exon 4 of the E1 alpha gene revealed that the mother was a heterozygotes. Complementary DNA restriction analysis and methylation analysis of the X chromosome DXS255 loci revealed skewed activation of the mutant allele, consistent with the deficient pyruvate dehydrogenase activity in the mother's fibroblasts. The milder maternal phenotype is consistent with variable X-inactivation patterns in different organs of female heterozygotes.
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PMID:Pyruvate dehydrogenase deficiency: molecular basis for intrafamilial heterogeneity. 802 67

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)
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PMID:[Mitochondrial encephalomyopathy associated with parkinsonism and a point mutation in the mitochondrial tRNA(Leu)(UUR)) gene]. 802 31

A 17-year-old girl was admitted to our hospital because of drowsiness, diplopia and gait difficulty. She had been well until ten days before admission when fever, drowsiness, headache and general fatigue developed. On admission, there were drowsiness, ophthalmoplegia, ataxia and hyporeflexia. CSF cells and anti-CMV antibody titers increased. CMV-DNA was detected in the CSF by the polymerase chain reaction (PCR). Serum anti-GQ1b antibody was positive. During recovery, forced laughing temporarily appeared. The neurological symptoms disappeared completely. CSF anti-CMV antibody titers became normalized and CSF CMV-DNA-PCR became negative. This is the first case report of Bickerstaff's brainstem encephalitis associated with CMV infection.
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PMID:[Bickerstaff's brainstem encephalitis associated with cytomegalovirus infection]. 802 40

A 66-year-old woman with hereditary deafness and multiple symmetric lipomas presented with ataxia, slight myopathy, and neuropathy. Molecular genetic analysis of mitochondrial DNA revealed the adenine to guanine transition at position 8344 in the tRNA gene for lysine that has been associated with the myoclonic epilepsy and ragged red fiber (MERRF) syndrome. The deafness was transmitted by the patient's father and may have been an unrelated autosomal defect rather than a paternally transmitted mitochondrial point mutation.
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PMID:Ekbom's syndrome: lipomas, ataxia, and neuropathy with MERRF. 771 38

Mutation of mitochondrial (mt) DNA at nucleotide (nt) 8993 has been reported to cause neurogenic weakness, ataxia, retinitis pigmentosa (NARP), or Leigh syndrome (LS). We report a family in whom the mutation was expressed clinically as LS and hypertrophic cardiomyopathy (CMP) in a boy who presented with a history of developmental delay and hypotonia, and who had recurrent lactic acidosis. The mother's first pregnancy resulted in the birth of a stillborn female; an apparently healthy older brother had died suddenly (SIDS) at age 2 months. MtDNA analysis identified the presence of the T8993G point mutation, which was found to be heteroplasmic in the patient's skeletal muscle (90%) and fibroblasts (90%). The identical mutation was present in leukocytes (38%) isolated from the mother, but not from the father or maternal grandmother. Our findings expand the clinical phenotype of the nt 8993 mtDNA mutation to include hypertrophic cardiomyopathy and confirm its cause of LS.
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PMID:Leigh syndrome and hypertrophic cardiomyopathy in an infant with a mitochondrial DNA point mutation (T8993G). 804 71

Linkage studies with DNA polymorphic markers allowed to map the loci of three inherited ataxia and to explore genetic heterogeneity in inherited ataxia in general. The locus of Friedreich ataxia, the most frequent of all recessive ataxias, has been mapped in 9q13-q21. In addition, Friedreich ataxia is an homogeneous genetic entity since all families from all populations tested (mainly European, North-American and from the Mediterranean basin) show linkage with this locus. But the severity of the disease varied in a few families. A form of recessive ataxia associated with a selective and severe serum vitamin E deficiency, which frequently presents clinically like typical Friedreich ataxia, is not linked to 9q13-q21 markers. The autosomal recessive spastic ataxia from Charlevoix-Saguenay (a region of Quebec) is also not linked to these markers. Both entities are therefore distinct genetically from Friedreich ataxia. Among dominant ataxias, the most important group is olivo-ponto-cerebellar ataxia which is heterogeneous and for which any classification is hindered by important intra-familial variability. This group corresponds to at least three distinct loci, two of which have been mapped, one in 6p23-p24, and the other, more recently, on chromosome 12. Prenatal and presymptomatic diagnosis based on linked markers can be made for the three mapped ataxias, but only in families with an affected individual for whom the diagnosis has been ascertained by through clinical investigation or by linkage analysis if the family is large enough (mainly for the dominant diseases). Linked markers are also the first tools for the search of the defective genes by positional cloning.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Molecular genetics and familial ataxia]. 809 Oct 82

The triplet repeat sequences (CGG)n, (GCT)n, and (CAG)n, which naturally occur in the human genome, can be autonomously expanded in human DNA by an as yet unknown mechanism. These in part excessive expansions have been causally related to human genetic diseases, the fragile X (Martin-Bell) syndrome, to myotonic dystrophy (Curschmann-Steinert), to spinal and bulbar muscular atrophy (Kennedy disease), and recently to Huntington disease. A GCC trinucleotide repeat was found to be expanded and methylated in the fragile site FRAXE on the human X chromosome. These findings were associated with mental retardation (Knight et al., 1993). In spinocerebellar ataxia type 1 (SCA1), a polymorphic CAG repeat was found to be unstable and expanded in individuals with that disease (Orr et al., 1993). We have demonstrated in in vitro experiments that the synthetic oligodeoxyribonucleotides (CGG)17, (CGG)12, (GCC)17, (CG)25, (CTG)17, or (CAG)17 plus (GTC)17, in the absence of added natural DNA, can be expanded with Taq polymerase in the polymerase chain reaction (PCR). Some expansion can already be detected after 4 PCR cycles. The E. coli Klenow DNA polymerase also functions in a similar amplification and expansion reaction performed at 37 degrees C without cycling. Other oligodeoxyribonucleotides, like, (CGG)7, (CGGT)13, or (TAA)17, are devoid of this property or have very low activity. The cytidine-methylated polymers (GCC)17 or (CG)25 yield expansion products of considerably reduced chain lengths. The expansion of the polymer (CGG)17 is affected by cytidine methylation to a lesser degree. A specific sequence and/or secondary structure and high CG content appear to be requirements for this expansion reaction by a possible slippage mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzymatic amplification of synthetic oligodeoxyribonucleotides: implications for triplet repeat expansions in the human genome. 811 62


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