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)

The mitochondrial DNA (mtDNA) transfer RNA (tRNA)Lys A-->G(8344) mutation was identified in seven patients. These patients and their relatives were assessed clinically; in one family the mutation was deduced to be present in four generations. The phenotype in index cases was consistent with the syndrome of myoclonic epilepsy with ragged red fibres, with the core clinical features of myoclonus, ataxia and seizures. Amongst other features, progressive external ophthalmoplegia, Leigh's syndrome and stroke-like episodes were observed, well recognized in mitochondrial myopathies but novel manifestations of this genotype. Samples of blood and muscle were analysed for the proportion of mutant mtDNA using an oligonucleotide hybridization technique. The proportion of mutant mtDNA in blood was significantly greater in symptomatic than asymptomatic cases. Furthermore, the proportion of mutant mtDNA in blood correlated with age of onset of disease and clinical severity assessed by a simple scale. Study of disease associated with the tRNA(Lys) A-->G(8344) mutation provides further insight into the pathogenesis and transmission of mitochondrial diseases. Quantification of the proportion of mtDNA in tissues demonstrates that this is a major factor determining the course of disease, but other, as yet unidentified factors are also likely to play a role.
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PMID:The mitochondrial DNA transfer RNA(Lys)A-->G(8344) mutation and the syndrome of myoclonic epilepsy with ragged red fibres (MERRF). Relationship of clinical phenotype to proportion of mutant mitochondrial DNA. 851 95

This man with myoclonus epilepsy and ragged red fibres (MERRF) syndrome due to the tRNA(Lys) A-->G(8344) mutation of mitochondrial DNA (mtDNA) died of bronchopneumonia at 18 years of age. He had progressive clinical symptoms from 6 months of age manifesting as ataxia, myoclonic seizures, and muscle weakness. A post-mortem examination revealed 91-99% mutated mtDNA in all 32 examined tissue samples, including various organs and different brain regions. The brain appeared without macroscopic changes, but microscopic examination showed degeneration with loss of nerve cells and gliosis affecting the globus pallidus, substantia nigra, red nucleus, dentate nucleus, inferior olivary nucleus, cerebellar cortex, and the spinal cord. Skeletal muscle showed cytochrome c oxidase deficient muscle fibres with proliferation of mitochondria. In addition to pathological changes of muscle and brain there were few morphological changes that could be attributed to his mitochondrial disease. These data support the concept that in patients with the tRNA(Lys) A-->G(8344) mutation who are manifesting disease there are high levels of mutated mtDNA in all tissues, but only some tissues and brain regions are vulnerable.
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PMID:Tissue distribution and disease manifestations of the tRNA(Lys) A-->G(8344) mitochondrial DNA mutation in a case of myoclonus epilepsy and ragged red fibres. 852 9

The present study was undertaken to investigate the involvement of nitric oxide (NO) in the behaviors induced by 1-(1-phenylcyclohexyl) piperidine (phencyclidine; PCP) in mice, using N(G)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthase. PCP (1, 3, and 10 mg/kg s.c.) dose dependently induced hyperlocomotion and stereotyped behaviors, including sniffing, head movement, and ataxia, in mice. PCP also caused a marked deficit of motor coordination in mice, the effect being exerted in a dose-dependent manner. Although pretreatment with L-NAME (50 mg/kg i.p.) slightly enhanced the ataxia induced by PCP (3 mg/kg), it failed to modify other stereotyped behaviors and the lack of motor coordination induced by PCP (2 mg/kg). The hyperlocomotion induced by PCP (3 mg/kg) was significantly enhanced by L-NAME (5 and 50 mg/kg) and 7-nitro indazole (25 mg/kg), but not by D-NAME (50 mg/kg), a less active enantiomer of L-NAME. However, the behavioral changes induced by PCP, at the high dose, 10 mg/kg, were not enhanced by L-NAME and D-NAME. The enhancing effects of L-NAME on the PCP (3 mg/kg)-induced hyperlocomotion were significantly prevented by L-arginine (1 g/kg i.p.). However, D-arginine (1 g/kg i.p.) and L-lysine (1 g/kg i.p.) had no effect in this regard. These results suggested the involvement of central NO production in the mediation of PCP-induced behaviors, hyperlocomotion in particular, in mice.
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PMID:Involvement of nitric oxide in phencyclidine-induced hyperlocomotion in mice. 860 91

Many proteins contain reiterated glutamine residues, but polyglutamine of excessive length may result in human disease by conferring new properties on the protein containing it. One established property of a glutamine residue, depending on the nature of the flanking residues, is its ability to act as an amine acceptor in a transglutaminase-catalyzed reaction and to make a glutamyl-lysine cross-link with a neighboring polypeptide. To learn whether glutamine repeats can act as amine acceptors, we have made peptides with variable lengths of polyglutamine flanked by the adjacent amino acid residues in the proteins associated with spinocerebellar ataxia type 1 (SCA1), Machado-Joseph disease (SCA3), or dentato-rubral pallidoluysian atrophy (DRPLA) or those residues adjacent to the preferred cross-linking site of involucrin, or solely by arginine residues. The polyglutamine was found to confer excellent substrate properties on any soluble peptide; under optimal conditions, virtually all the glutamine residues acted as amine acceptors in the reaction with glycine ethyl-ester, and lengthening the sequence of polyglutamine increased the reactivity of each glutamine residue. In the presence of transglutaminase, peptides containing polyglutamine formed insoluble aggregates with the proteins of brain extracts and these aggregates contained glutamyl-lysine cross-links. Repeated glutamine residues exposed on the surface of a neuronal protein should form cross-linked aggregates in the presence of any transglutaminase activated by the presence of Ca2+.
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PMID:Peptides containing glutamine repeats as substrates for transglutaminase-catalyzed cross-linking: relevance to diseases of the nervous system. 896 45

Infants with macrocephaly, young children with acute disease resembling encephalitis, and children with truncal hypotonia, ataxia, or dystonia may be affected by glutaric aciduria type I (GA 1, glutaryl-CoA-dehydrogenase deficiency), a not-so-rare autosomal recessive neurometabolic disease. Well-known features of GA1 are fronto-temporal brain atrophy with macrocephaly and acute encephalopathic episodes with striatal necrosis followed by dystonia, but some patients develop motor disease without overt crises and other biochemically affected individuals remain asymptomatic. Biochemical and molecular characterization is available and allows post- and prenatal diagnosis. The pathogenesis of fronto-temporal atrophy, macrocephaly, and basal ganglia necrosis is still not understood, and there is no close correlation between biochemical parameters and clinical outcome. There is, however, evidence suggesting that carnitine supplementation and anticatabolic treatment of intercurrent illness may arrest or prevent neurological deterioration, while the role of limitation of dietary lysine and tryptophane is not yet clear. Although pathogenetic aspects are poorly understood, the natural course of glutaric aciduria type 1 can be changed by early diagnosis and treatment. Coordinated research is needed to understand the pathogenesis of brain toxicity, to define the role of dietary therapy, and to explore the possibility of neonatal screening.
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PMID:Glutaric aciduria type 1 (glutaryl-CoA-dehydrogenase deficiency): advances and unanswered questions. Report from an international meeting. 939 91

Rapid progress has been made in the identification of mitochondrial DNA mutations which are typically associated with diseases of the nervous system and muscle. The well established mitochondrial disorders are maternally inherited and males and females are equally affected. An exception is Leber's hereditary optic atrophy (LHON) which is observed much more frequently in males than in females. There are three common point mutations in LHON which can be homoplasmic or heteroplasmic. In mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) most mutations are single base changes and lie within the tRNA-Leu gene. Point mutations in myoclonic epilepsy with ragged red fibres (MERRF) usually occur within the tRNA-Lys gene but mutations of the tRNA-Leu gene are also observed. MELAS and MERRF mutations are heteroplasmic and there is considerable clinical overlap between these diseases. Point mutations within the ATPase6 gene result in either neuropathy, ataxia and retinitis pigmentosa (NARP) or in Leigh's syndrome. The latter occurs if the mutation is present in the majority of mitochondria (extreme heteroplasmy). Finally, mitochondrial DNA deletions are the cause underlying Kearns-Sayre syndrome (KSS). Apart from the well-established mitochondrial diseases, there is increasing evidence that mitochondrial mutations may also play a role in the neurodegenerative disorders Parkinson, Alzheimer and Huntington disease. The complex I defect found in Parkinson disease is especially interesting in this respect. However, no causative mitochondrial mutation has as yet been established in any of these three common disorders.
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PMID:Recent developments in the molecular genetics of mitochondrial disorders. 951 82

Among the epilepsies, the progressive myoclonus epilepsies (PMEs) form a heterogeneous group of rare diseases characterized by myoclonus, epilepsy, and progressive neurologic deterioration, particularly dementia and ataxia. The success of the Human Genome Project and the fact that most PMEs are inherited through a mendelian or mitochondrial mode have resulted in important advances in the definition of the molecular basis of PME. The gene defects for the most common forms of PME (Unverricht-Lundborg disease, the neuronal ceroid lipofuscinoses, Lafora disease, type I sialidosis, and myoclonus epilepsy with ragged-red fibers) have been either identified or mapped to specific chromosome sites. Unverricht-Lundborg disease has been shown to be caused by mutations in the gene that codes for cystatin B, an inhibitor of cysteine protease. The most common mutation in Unverricht-Lundborg disease is an expansion of a dodecamer repeat located in a noncoding region upstream of the transcription start site of the cystatin B gene, making it the first human disease associated with instability of a dodecamer repeat. Juvenile neuronal ceroid lipofuscinosis is caused by mutations in the CLN3 gene, a gene of unknown function that encodes a 438-amino-acid protein of possible mitochondrial location. Other forms of neuronal ceroid lipofuscinosis that occur as PME and Lafora disease have been mapped by means of linkage analysis, but the corresponding gene defects remain unknown. Sialidosis has been shown to be caused by mutations in the sialidase gene, and myoclonus epilepsy with ragged-red fibers is well known to be caused by mutations in the mitochondrial gene that codes for tRNA(Lys). How the different PME gene defects described produce the various PME phenotypes, including epileptic seizures, remains unknown. The development of animal models that bear these mutations is needed to increase our knowledge of the basic mechanisms involved in the PMEs. This knowledge should lead to the development of new and effective forms of therapy, which are especially lacking for the PMEs.
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PMID:The molecular genetic bases of the progressive myoclonus epilepsies. 1051 28

We report a family with a heterogeneous group of neurologic disorders associated with the mitochondrial DNA G8363A transfer ribonucleic acid (RNA)Lys mutation. The phenotype of one child in the family was consistent with autism. During his second year of life, he lost previously acquired language skills and developed marked hyperactivity with toe-walking, abnormal reciprocal social interaction, stereotyped mannerisms, restricted interests, self-injurious behavior, and seizures. Brain magnetic resonance imaging (MRI) and repeated serum lactate studies were normal. His older sister developed signs of Leigh syndrome with progressive ataxia, myoclonus, seizures, and cognitive regression. Her laboratory studies revealed increased MRI T2-weighted signal in the putamen and posterior medulla, elevated lactate in serum and cerebrospinal fluid, and absence of cytochrome c oxidase staining in muscle histochemistry. Molecular analysis in her revealed the G8363A mutation of the mitochondrial transfer RNA(Lys) gene in blood (82% mutant mitochondrial DNA) and muscle (86%). The proportions of mutant mitochondrial DNA from her brother with autism were lower (blood 60%, muscle 61%). It is likely that the origin of his autism phenotype is the pathogenic G8363A mitochondrial DNA mutation. This observation suggests that certain mitochondrial point mutations could be the basis for autism in some individuals.
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PMID:Autism associated with the mitochondrial DNA G8363A transfer RNA(Lys) mutation. 1086 77

A 3.5-year-old boy with developmental motor retardation, hypotonicity, and severe speech disturbance had alpha-amino adipic acid in his blood and very high levels in his urine. In only 20 cases has this catabolite of lysine and hydroxylysine been found in high concentrations in urine, due to enzymatic block. The clinical features associated with alpha-amino adipic aciduria may include mental retardation, developmental and motor delay, learning difficulties, convulsions, speech problems and ataxia. 3 siblings had milder symptoms of psychomotor delay and intermediate degrees of alpha amino-adipic aciduria, suggesting that the described developmental deficits could be related to this metabolite or its derivatives.
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PMID:[Alpha-amino adipic aciduria: a rare psychomotor syndrome]. 1095 42

The genetic progressive myoclonus epilepsies (PMEs) are clinically characterized by the triad of stimulus sensitive myoclonus (segmental lightning like muscular jerks), epilepsy (grand mal and absences) and progressive neurologic deterioration (dementia, ataxia, and various neurologic signs depending on the cause). Etiologically heterogenous, PMEs are rare and mostly autosomal recessive disorders, with the exception of autosomal dominant dentatorubral-pallidoluysian atrophy and mitochondrial encephalomyopathy with ragged red fibers (MERRF). In the last five years, specific mutations have been defined in Lafora disease (gene for laforin or dual specificity phosphatase in 6q24), Unverricht-Lundborg disease (cystatin B in 21q22.3), Jansky-Bielschowsky ceroid lipofuscinoses (CLN2 gene for tripeptidyl peptidase 1 in 11q15), Finnish variant of late infantile ceroid lipofuscinoses (CLN5 gene in 13q21-32 encodes 407 amino acids with two transmembrane helices of unknown function), juvenile ceroid lipofuscinoses or Batten disease (CLN3 gene in 16p encodes 438 amino acid protein of unknown function), a subtype of Batten disease and infantile ceroid lipofuscinoses of the Haltia-Santavuori type (both are caused by mutations in palmitoyl-protein thiosterase gene at 1p32), dentadorubropallidoluysian atrophy (CAG repeats in a gene in 12p13.31) and the mitochondrial syndrome MERRF (tRNA Lys mutation in mitochondrial DNA). In this review, we cover mainly these rapid advances.
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PMID:Advances in the genetics of progressive myoclonus epilepsy. 1157 33


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