Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0007758 (cerebellar ataxia)
 3,609 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Episodic ataxia type 1 (EA1) is an autosomal dominant central nervous system potassium channelopathy characterized by brief attacks of cerebellar ataxia and continuous interictal myokymia. Point mutations in the voltage-gated potassium channel gene KCNA1 on chromosome 12p associate with EA1. We have studied 4 families and identified three new and one previously reported heterozygous point mutations in this gene. Affected members in Family A (KCNA1 G724C) exhibit partial epilepsy and myokymia but no ataxic episodes, supporting the suggestion that there is an association between mutations of KCNA1 and epilepsy. Affected members in Family B (KCNA1 C731A) exhibit myokymia alone, suggesting a new phenotype of isolated myokymia. Family C harbors the first truncation to be reported in KCNA1 (C1249T) and exhibits remarkably drug-resistant EA1. Affected members in Family D (KCNA1 G1210A) exhibit attacks typical of EA1. This mutation has recently been reported in an apparently unrelated family, although no functional studies were attempted. Heterologous expression of the proteins encoded by the mutant KCNA1 genes suggest that the four point mutations impair delayed-rectifier type potassium currents by different mechanisms. Increased neuronal excitability is likely to be the common pathophysiological basis for the disease in these families. The degree and nature of the potassium channel dysfunction may be relevant to the new phenotypic observations reported in this study.
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PMID:Clinical, genetic, and expression studies of mutations in the potassium channel gene KCNA1 reveal new phenotypic variability. 1102 49

Thirty years ago, antibodies against the muscle acetylcholine receptor (AChR) were recognized as the cause of myasthenia gravis. Since then, there has been great interest in identifying other neurological disorders associated with autoantibodies. Several other antibody-mediated neuromuscular disorders have been identified, each associated with an antibody against a ligand- or voltage-gated ion channel. The Lambert-Eaton syndrome is caused by antibodies against voltage-gated calcium channels and often occurs in patients with small cell lung cancer. Acquired neuromyotonia is caused by voltage-gated potassium channel antibodies, and autoimmune autonomic ganglionopathy is caused by antibodies against the neuronal AChR in autonomic ganglia. There is good evidence that antibodies in these disorders cause changes in synaptic function or neuronal excitability by directly inhibiting ion channel function. More recently, studies have identified ion channel antibodies in patients with certain CNS disorders, such as steroid-responsive encephalitis and paraneoplastic cerebellar ataxia. It remains unclear if antibodies can gain access to the CNS and directly cause ion channel dysfunction. Treatment of autoimmune channelopathies includes drugs that help restore normal neuronal function and treatments to remove pathogenic antibodies (plasma exchange) or modulate the immune response (steroids or immunosuppressants). These disabling neurological disorders may be dramatically responsive to immunomodulatory therapy. Future studies will likely lead to identification of other ion channel antibodies and other autoimmune channelopathies.
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PMID:Autoimmune and paraneoplastic channelopathies. 1739 41

A previously healthy 9-year-old girl presented with a 10-day history of slowly progressive unsteadiness, slurred speech, and behavior change. On examination there was cerebellar ataxia and dysarthria, excessive blinking, subtle perioral myoclonus, and labile mood. The finding of oligoclonal bands in the cerebrospinal fluid prompted paraneoplastic serological evaluation and search for an occult neural crest tumor. Antineuronal nuclear autoantibody type 1 (anti-Hu) and voltage-gated potassium channel complex antibodies were detected in serum. Metaiodobenzylguanidine scan and computed tomography scan of the abdomen showed a localized abdominal mass in the region of the porta hepatis. A diagnosis of occult neuroblastoma was made. Resection of the stage 1 neuroblastoma and treatment with pulsed corticosteroids resulted in resolution of all symptoms and signs. Excessive blinking has rarely been described with neuroblastoma, and, when it is not an isolated finding, it may be a useful clue to this paraneoplastic syndrome. Although voltage-gated potassium channel complex autoimmunity has not been described previously in the setting of neuroblastoma, it is associated with a spectrum of paraneoplastic neurologic manifestations in adults, including peripheral nerve hyperexcitability disorders.
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PMID:Excessive blinking and ataxia in a child with occult neuroblastoma and voltage-gated potassium channel antibodies. 2252 75

We report a female patient of German descent with a molecular diagnosis of SCA13 who presented with a history of cerebellar ataxia and epilepsy. The underlying mutation R420H had been shown to cause a dominant negative effect on the functional properties of the voltage-gated potassium channel KCNC3. Despite widespread KCNC3 expression in the central nervous system, the patient presented with a left mesiotemporal electroencephalogram focus and left hippocampal sclerosis. This is the first case, which reports an association between mesial temporal lobe epilepsy and spinocerebellar ataxia type 13. This demonstrates that epilepsy of structural-metabolic cause may be contingent upon genetically defined channelopathies.
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PMID:Mesial temporal lobe epilepsy in a patient with spinocerebellar ataxia type 13 (SCA13). 2321 17

A form of hereditary cerebellar ataxia has recently been described in the Norwegian Buhund dog breed. This study aimed to identify the genetic cause of the disease. Whole-genome sequencing of two Norwegian Buhund siblings diagnosed with progressive cerebellar ataxia was carried out, and sequences compared with 405 whole genome sequences of dogs of other breeds to filter benign common variants. Nine variants predicted to be deleterious segregated among the genomes in concordance with an autosomal recessive mode of inheritance, only one of which segregated within the breed when genotyped in additional Norwegian Buhunds. In total this variant was assessed in 802 whole genome sequences, and genotyped in an additional 505 unaffected dogs (including 146 Buhunds), and only four affected Norwegian Buhunds were homozygous for the variant. The variant identified, a T to C single nucleotide polymorphism (SNP) (NC_006585.3:g.88890674T>C), is predicted to cause a tryptophan to arginine substitution in a highly conserved region of the potassium voltage-gated channel interacting protein KCNIP4. This gene has not been implicated previously in hereditary ataxia in any species. Evaluation of KCNIP4 protein expression through western blot and immunohistochemical analysis using cerebellum tissue of affected and control dogs demonstrated that the mutation causes a dramatic reduction of KCNIP4 protein expression. The expression of alternative KCNIP4 transcripts within the canine cerebellum, and regional differences in KCNIP4 protein expression, were characterised through RT-PCR and immunohistochemistry respectively. The voltage-gated potassium channel protein KCND3 has previously been implicated in spinocerebellar ataxia, and our findings suggest that the Kv4 channel complex KCNIP accessory subunits also have an essential role in voltage-gated potassium channel function in the cerebellum and should be investigated as potential candidate genes for cerebellar ataxia in future studies in other species.
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PMID:Characterisation of canine KCNIP4: A novel gene for cerebellar ataxia identified by whole-genome sequencing two affected Norwegian Buhund dogs. 3199 92