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 ectopic expression of neuronal P/Q-type voltage-gated calcium channels in small cell lung carcinoma (SCLC) is thought to induce antisynaptic autoimmunity in the paraneoplastic Lambert-Eaton myasthenic syndrome. The gene CACNL1A4, encoding the principal (alpha1A) subunit of this calcium channel, is mutated in several inherited neurological disorders. One of these disorders (spinocerebellar ataxia, type 6, or SCA-6) involves the expansion of a trinucleotide (CAG) repeat unit. We hypothesized that a somatic CAG repeat instability of this gene in neoplastic cells might generate a non-self epitope capable of initiating autoimmunity to P/Q-type calcium channels. We therefore analyzed the CACNL1A4 gene in SCLC lines established from metastases derived from seven individual patients (four associated with Lambert-Eaton myasthenic syndrome, one associated with myasthenia gravis, and two not associated with neurological autoimmunity). We compared their CAG repeat numbers (determined by polymerase chain reaction (PCR) amplification followed by separation of products on a 6% polyacrylamide/8M urea gel) to published norms and to DNA from a patient with SCA-6. The number of CAG repeats in SCLC DNA fell within a normal range whether or not the neoplasm was complicated by neurological autoimmunity. Therefore, it is unlikely that somatically unstable CAG repeat units in the gene encoding the P/Q-type voltage-gated calcium channel account for this tumor protein's immunogenicity in the Lambert-Eaton myasthenic syndrome.
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PMID:Immunogenicity of P/Q-type calcium channel in small cell lung cancer: investigation of alpha1 subunit polyglutamine expansion. 1067 74

A 57-year-old man was admitted to our hospital in November 1997 because of dysarthria, progressive ataxia, generalized weakness, and incoordination in both hands. He had been aware of the dysarthria 6 months earlier. Chest roentgenograms and computed tomographic films disclosed a 5 cm x 6 cm mass in the left S3b. The patient was given a diagnosis of small cell lung cancer (T3N2M0, stage IIIA) associated with paraneoplastic cerebellar degeneration (PCD). Three courses of chemotherapy (carboplatin and etoposide) eliminated the tumor and slightly alleviated the PCD symptoms. In March 1998, electromyograms revealed a fall in the single-stimulated M wave and a waxing phenomenon that had not been observed on admission. Anti-P/Q type voltage gated calcium channel antibody was detected in serum samples obtained on admission and after chemotherapy. These findings confirmed an association with Lambert-Eaton myasthenic syndrome. No relapse of the tumor has been observed 15 months after the last course of chemotherapy.
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PMID:[Small cell lung cancer associated with paraneoplastic cerebellar degeneration and Lambert-Eaton myasthenic syndrome]. 1070 41

Abnormal CAG repeat expansion in the alpha1A voltage-dependent calcium channel gene is associated with spinocerebellar ataxia type 6, an autosomal dominant cerebellar ataxia with a predominant loss of the Purkinje cell. A reverse transcriptase-polymerase chain reaction analysis of mRNA from mouse Purkinje cells revealed a predominant expression of the alpha1A channel lacking an asparagine-proline (NP) stretch in the domain IV (alpha1A(-NP)). Human alpha1A channels carrying various polyglutamine length with or without NP were expressed in HEK293 cells, and channel properties were compared using a whole-cell voltage clamp technique. alpha1A(-NP), corresponding to P-type channel, with 24 and 28 polyglutamines found in patients showed the voltage dependence of inactivation shifting negatively by 6 and 11 mV, respectively, from the 13 polyglutamine control. Contrarily, the alpha1A channel with NP (alpha1A(+NP)), corresponding to Q-type channel, with 28 polyglutamines exhibited a positive shift of 5 mV. These results suggest that altered function of alpha1A(-NP) may contribute to degeneration of Purkinje cells, which express predominantly alpha1A(-NP), due to the reduced Ca(2+) influx resulting from the negative shift of voltage-dependent inactivation. On the other hand, other types of neurons, expressing both alpha1A(-NP) and alpha1A(+NP), may survive because the positive shift of voltage-dependent inactivation of alpha1A(+NP) compensates Ca(2+) influx.
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PMID:Spinocerebellar ataxia type 6 mutation alters P-type calcium channel function. 1075 86

Inactivation of the beta4 subunit of the calcium channel in the mouse neurological mutant lethargic results in a complex neurological disorder that includes absence epilepsy and ataxia. To determine the role of the calcium-channel beta4-subunit gene CACNB4 on chromosome 2q22-23 in related human disorders, we screened for mutations in small pedigrees with familial epilepsy and ataxia. The premature-termination mutation R482X was identified in a patient with juvenile myoclonic epilepsy. The R482X protein lacks the 38 C-terminal amino acids containing part of an interaction domain for the alpha1 subunit. The missense mutation C104F was identified both in a German family with generalized epilepsy and praxis-induced seizures and in a French Canadian family with episodic ataxia. These coding mutations were not detected in 255 unaffected control individuals (510 chromosomes), and they may be considered candidate disease mutations. The results of functional tests of the truncated protein R482X in Xenopus laevis oocytes demonstrated a small decrease in the fast time constant for inactivation of the cotransfected alpha1 subunit. Further studies will be required to evaluate the in vivo consequences of these mutations. We also describe eight noncoding single-nucleotide substitutions, two of which are present at polymorphic frequency, and a previously unrecognized first intron of CACNB4 that interrupts exon 1 at codon 21.
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PMID:Coding and noncoding variation of the human calcium-channel beta4-subunit gene CACNB4 in patients with idiopathic generalized epilepsy and episodic ataxia. 1076 41

Autosomal-dominant cerebellar ataxias (ADCA) may present as progressive or paroxysmal disorders. While the progressive ataxias have been named spinocerebellar ataxias (SCA), the paroxysmal disorders are designated episodic ataxias (EA). Until now, three different mutational mechanisms resulting in distinctive pathogenesis have been identified. The first type of mutation present in SCA1, SCA2, SCA3, and SCA7 is an expanded CAG repeat in genes of unknown function that are translated into proteins with expanded polyglutamine tracts. A common ultrastructural feature of these disorders is the formation of neuronal intranuclear inclusions (NII) harboring the expanded disease proteins and a variety of other proteins. The pathogenic role of these inclusions has yet to be clarified. A second group of disorders is the result of mutations in genes that code for ion channels. In EA-1, a disorder characterized by episodes of ataxia provoked by movement and startle, missense mutations in a potassium channel gene, KCNA1, have been found. Patients with EA-2, another form of paroxysmal ataxia, carry nonsense mutations of the gene encoding the alpha1A voltage-dependent calcium channel subunit, CACNA1A, that are predicted to result in truncated channel proteins. In SCA6, a progressive ataxia, an expanded CAG repeat in the 3' translated region of the CACNA1A gene, has been found. The third type of mutation is an untranslated CTG expansion resembling the mutation found in myotonic dystrophy. It is associated with a progressive ataxia, SCA8.
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PMID:The molecular biology of the autosomal-dominant cerebellar ataxias. 1092 70

Spinocerebellar ataxia type 6 (SCA6) was recently identified as a form of autosomal dominant spinocerebellar ataxia associated with a small CAG repeat expansion of the gene encoding an alpha 1 A-voltage-dependent calcium channel gene subunit on chromosome 19p13. In this study 50-microm-thick sections of cerebellar tissue from one patient with SCA6 were subjected to free-floating immunohistochemical staining with calbindin-D and parvalbumin antibodies. Severe loss of Purkinje cells was found, particularly in the vermis, and various morphological changes in Purkinje cells and their dendritic arborizations were demonstrated. Many of the remaining Purkinje cells were found to have heterotopic, irregularly shaped nuclei, an unclear cytoplasmic membrane outline, and somatic sprouts. Increased numbers of spine-like protrusions from swelling dendritic arborizations were found in the molecular layer. The axonal arrangement was disordered, and many torpedos were found in the granular layer and white matters. These morphological changes are completely different from those observed in paraneoplastic cerebellar degeneration (PCD) and multiple system atrophy (MSA) and are considered to be related to the genetic abnormality that causes abnormal development of Purkinje cells.
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PMID:Morphological Purkinje cell changes in spinocerebellar ataxia type 6. 1098 94

Familial hemiplegic migraine is a hereditary form of migraine in which the aura includes a certain degree of motor deficit. A first gene responsible for this disease was located on chromosome 19 in 1993, and identified in 1996. It encodes the principal alpha 1-subunit of a potential-dependent calcium channel, the P/Q channel, which is selectively expressed in the nervous system. This channel is particularly rich in nerve terminals, where it contributes to the triggering and release of neuromediators. In patients with hemiplegic migraine, mis-sense mutations have been detected which result in a modification of channel function. Other mutations which lead to the synthesis of inactive protein truncations have been described in another disease, type 2 episodic ataxia. In the mouse, mutations in the same gene lead to different phenotypes (tottering mouse, leaner mouse). Finally, possible links between P/Q calcium channel dysfunction and migraine have been discussed.
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PMID:[Calcium channels and migraine]. 1107 42

Familial episodic ataxias are unusual hereditary disorders of early onset characterized by recurrent episodes of ataxia. Most patients recover fully between attacks, but some may develop progressive ataxia with cerebellar atrophy. There are two subtypes of episodic ataxia: type 1 (EA1), with interictal myokymia, and type 2 (EA2), with interictal nystagmus. Stress and fatigue can trigger ataxic spells, which can be responsive to acetazolamide. These clinical features are reminiscent of other channelopathies or paroxysmal neurologic disorders with progressive features caused by ion channel mutations. Familial episodic ataxias indeed are channelopathies. EA1 is caused by mutations in a potassium channel-encoding gene, whereas EA2 is caused by mutations in a calcium channel-encoding gene, which is also the disease-causing gene in spinocerebellar ataxia type 6 and several kindreds with familial hemiplegic migraine. Treatment with acetazolamide can be effective in decreasing the frequency of attacks and is generally well tolerated. Understanding the mechanism of action of acetazolamide and the functional consequences of these mutations will help one to develop a rational pharmacologic treatment for these disorders, which may share similar mechanisms with benign recurrent vertigo and more common forms of migraine.
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PMID:Familial Episodic Ataxias and Related Ion Channel Disorders. 1109 68

We describe the association of recurrent complicated febrile convulsions, developmental delay, ataxia, and obesity in three unrelated girls. The three girls, aged 3 to 4 years, were all born to healthy, nonconsanguineous parents and have normal siblings. Their birth weight was appropriate for gestational age. They are not dysmorphic and have normal head circumference. Development is delayed; they all walked with an ataxic gait after the age of 2 years and started speaking at 3 years. Their growth charts are remarkably alike: they initially had a normal growth curve and around 24 months of age started to gain weight excessively. They all continue to suffer from complicated febrile seizures, which started before 12 months of age, and are resistant to prophylactic anticonvulsants. Metabolic evaluation is normal. They have normal magnetic resonance images and electroencephalograms. Fragile X and Prader-Willi syndromes were ruled out. We suggest that this is a new mental retardation syndrome that should be considered in children with recurrent febrile convulsions, developmental delay, and obesity. In a recent study, mutations in the beta4 calcium channel were identified in the mutant epileptic mouse that presents with epilepsy, mental retardation, and ataxia. We hypothesize that a calcium channel gene may be involved in this syndrome.
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PMID:Febrile convulsions, ataxia, developmental delay, and obesity: a new syndrome? 1130 85

We describe here familial dyskinesia and facial myokymia (FDFM), a novel autosomal dominant disorder characterized by adventitious movements that sometimes appear choreiform and that are associated with perioral and periorbital myokymia. We report a 5-generation family with 18 affected members (10 males and 8 females) with FDFM. The disorder has an early childhood or adolescent onset. The involuntary movements are paroxysmal at early ages, increase in frequency and severity, and may become constant in the third decade. Thereafter, there is no further deterioration, and there may even be improvement in old age. The adventitious movements are worsened by anxiety but not by voluntary movement, startle, caffeine, or alcohol. The disease is socially disabling, but there is no intellectual impairment or decrease in lifespan. A candidate gene and haplotype analysis was performed in 9 affected and 3 unaffected members from 3 generations of this family using primers for polymorphic loci closely flanking or within genes of interest. We excluded linkage to 11 regions containing genes associated with chorea and myokymia: 1) the Huntington disease gene on chromosome 4p; 2) the paroxysmal dystonic choreoathetosis gene at 2q34; 3) the dentatorubral-pallidoluysian atrophy gene at 12p13; 4) the choreoathetosis/spasticity disease locus on 1p that lies in a region containing a cluster of potassium (K+) channel genes; 5) the episodic ataxia type 1 (EA1) locus on 12p that contains the KCNA1 gene and two other voltage-gated K+ channel genes, KCNA5 and KCNA6; 6) the chorea-acanthocytosis locus on 9q21; 7) the Huntington-like syndrome on 20p; 8) the paroxysmal kinesigenic dyskinesia locus on 16p11.2-q11.2; 9) the benign hereditary chorea locus on 14q; 10) the SCA type 5 locus on chromosome 11; and 11) the chromosome 19 region that contains several ion channels and the CACNA1A gene, a brain-specific P/Q-type calcium channel gene associated with ataxia and hemiplegic migraine. Our results provide further evidence of genetic heterogeneity in autosomal dominant movement disorders and suggest that a novel gene underlies this new condition.
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PMID:Familial dyskinesia and facial myokymia (FDFM): a novel movement disorder. 1131 Jun 26


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