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 Na(+)-independent alanine-serine-cysteine transporter 1 (Asc-1) is exclusively expressed in neuronal structures throughout the central nervous system (CNS). Asc-1 transports small neutral amino acids with high affinity especially for D-serine and glycine (K(i): 8-12 microM), two endogenous glutamate co-agonists that activate N-methyl-D-aspartate (NMDA) receptors through interacting with the strychnine-insensitive glycine binding-site. By regulating D-serine (and possibly glycine) levels in the synaptic cleft, Asc-1 may play an important role in controlling neuronal excitability. We generated asc-1 gene knockout (asc-1(-/-)) mice to test this hypothesis. Behavioral phenotyping combined with electroencephalogram (EEG) recordings revealed that asc-1(-/-) mice developed tremors, ataxia, and seizures that resulted in early postnatal death. Both tremors and seizures were reduced by the NMDA receptor antagonist MK-801. Extracellular recordings from asc-1(-/-) brain slices indicated that the spontaneous seizure activity did not originate in the hippocampus, although, in this region, a relative increase in evoked synaptic responses was observed under nominal Mg(2+)-free conditions. Taken together with the known neurochemistry and neuronal distribution of the Asc-1 transporter, these results indicate that the mechanism underlying the behavioral hyperexcitability in mutant mice is likely due to overactivation of NMDA receptors, presumably resulting from elevated extracellular D-serine. Our study provides the first evidence to support the notion that Asc-1 transporter plays a critical role in regulating neuronal excitability, and indicate that the transporter is vital for normal CNS function and essential to postnatal survival of mice.
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PMID:Lack of the alanine-serine-cysteine transporter 1 causes tremors, seizures, and early postnatal death in mice. 1602 68

Ataxic movement, the common major symptom of spinocerebellar atrophy, has been considered to involve impaired glutamatergic excitatory neurotransmission in the cerebellum. Considering the therapeutic importance of ataxia control, we assessed the effectiveness of increasing the extracellular concentration of glycine by administering it exogenously or via blockade of glycine transporter 1, using its selective inhibitors sarcosine and N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl]sarcosine (NFPS), for amelioration of motor ataxia in a mouse model of spinocerebellar atrophy developing after neonatal treatment with cytosine beta-D-arabinofuranoside. Intracerebroventricular (i.c.v.) injection of sarcosine (3, 10, and 30 microg) and NFPS (0.01 and 0.03 microg) reduced the number of falls without affecting spontaneous motor activity, and therefore the falling index [(number of falls / spontaneous motor activity) x 100], and dose-dependently ameliorated ataxic movements. Similar effects were observed upon i.c.v. injection of D-serine (1 and 10 microg), an agonist of the glycine-recognition site of the N-methyl-D-aspartate (NMDA) receptor. However, exogenously injected glycine (1, 3, and 10 microg, i.c.v.) only weakly ameliorated the ataxic movements at 3 microg. These results suggest the therapeutic relevance of GlyT1 inhibitors for amelioration of motor ataxia in spinocerebellar atrophy by increasing the endogenous concentration of glycine near the glycine-recognition site of the NMDA receptor.
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PMID:Glycine transporter blockade ameliorates motor ataxia in a mouse model of spinocerebellar atrophy. 1927 Apr 29

Glucose transporter 1 deficiency syndrome (Glut1-DS) is a congenital metabolic disorder characterized by refractory seizures with early infantile onset, developmental delay, movement disorders and acquired microcephaly. Glut1-DS is caused by heterozygous abnormalities of the SLC2A1 (Glut1) gene, whose product acts to transport glucose into the brain across the blood-brain barrier. We analyzed the SLC2A1 gene in 12 Japanese Glut1-DS patients who were diagnosed by characteristic clinical symptoms and hypoglycorrhachia as follows: all patients had infantile-onset seizures and mild to severe developmental delay, and ataxia was detected in 11 patients. For the 12 patients, we identified seven different mutations (three missense, one nonsense, two frameshift and one splice-site) in exons and exon-intron boundaries of the SLC2A1 gene by direct sequencing, of which six were novel mutations. Of the remaining five patients who had no point mutations and underwent investigation by multiplex ligation-dependent probe amplification, a complex abnormality with deletion and duplication was identified in one patient: this is the first case of such recombination of the SLC2A1 gene. Changes in regulatory sequences in the promoter region or genes other than SLC2A1 might be responsible for onset of Glut1-DS in the other four patients (33%) without SLC2A1 mutation.
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PMID:SLC2A1 gene analysis of Japanese patients with glucose transporter 1 deficiency syndrome. 2201 17

Glucose transporter 1 deficiency syndrome (OMIM 606777) is a treatable epileptic encephalopathy caused by mutations in the SLC2A1 gene (OMIM 138140) causing impaired glucose transport into the brain. The classical phenotype is associated with seizures, developmental delay, ataxia and spasticity; however, milder phenotypes are emerging. We describe an 8-year-old boy with glucose transporter 1 deficiency syndrome whose clinical presentation was dominated by hemiplegic migraines that resolved with institution of a modified Atkins diet.
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PMID:Glucose transporter 1 deficiency syndrome and hemiplegic migraines as a dominant presenting clinical feature. 2544 Jan 61

Episodic ataxias (EAs) are rare channelopathies characterized by recurrent ataxia and vertigo, having eight subtypes. Mutated genes were found in four of these eight subtypes (EA1, EA2, EA5, and EA6). To date, only four missense mutations in the Solute Carrier Family 1 Member 3 gene (SLC1A3) have been reported to cause EA6. SLC1A3 encodes excitatory amino-acid transporter 1, which is a trimeric transmembrane protein responsible for glutamate transport in the synaptic cleft. In this study, we found a novel missense mutation, c.383T>G (p.Met128Arg) in SLC1A3, in an EA patient by whole-exome sequencing. The modeled structural analysis suggested that p.Met128Arg may affect the hydrophobic transmembrane environment and protein function. Analysis of the pathogenicity of all mutations found in SLC1A3 to date using multiple prediction tools showed some advantage of using the Mendelian Clinically Applicable Pathogenicity (M-CAP) score. Various types of SLC1A3 variants, including nonsense mutations and indels, in the ExAC database suggest that the loss-of-function mechanism by SLC1A3 mutations is unlikely in EA6. The current mutation (p.Med128Arg) presumably has a gain-of-function effect as described in a previous report.
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PMID:A novel mutation in SLC1A3 causes episodic ataxia. 2920 48