Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alternating hemiplegia of childhood is a rare syndrome characterized by onset before 18 months of age of frequent attacks of alternating paralysis, transient ocular palsies, nystagmus, choreoathetosis, and autonomic dysfunction. We describe features of 10 patients followed for up to 27 years. The mechanism of alternating hemiplegia remains unknown but an association to migraine is suspected because of the strong family history of migraine and aura symptoms in some patients. We treated nine patients with flunarizine, a calcium channel blocker, for up to 5 years; they showed a reduction in duration of the hemiplegic attacks, but the episodes ceased completely in only one patient. With long-term follow-up, the persistent motor, movement, and cognitive deficits are more apparent. It is not certain if the flunarizine alters this course.
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PMID:Alternating hemiplegia of childhood: a study of 10 patients and results of flunarizine treatment. 842 8

Point mutations of the CACNA1A gene coding for the alpha 1A voltage-dependent calcium channel subunit are responsible for familial hemiplegic migraine (FHM) and episodic ataxia type 2 (EA2). In addition, expansions of the CAG repeat motif at the 3' end of the gene, smaller than those responsible for dynamic mutation disorders, were found in patients with a progressive spinocerebellar ataxia, named SCA6. In the present work, the analysis of two new families with small CAG expansions of the CACNA1A gene is presented. In one family, with a clinical diagnosis of EA2, a CAG23 repeat allele segregated in patients showing different interictal symptoms, ranging from nystagmus only to severe progressive cerebellar ataxia. No additional mutations in coding and intron-exon junction sequences in disequilibrium with the CAG expansion were found. In the second family, initially classified as autosomal dominant cerebellar ataxia of unknown type, an inter-generational allele size change showed that a CAG20 allele was associated with an EA2 phenotype and a CAG25 allele with progressive cerebellar ataxia. These results show that EA2 and SCA6 are the same disorder with a high phenotypic variability, at least partly related to the number of repeats, and suggest that the small expansions may not be as stable as previously reported. A refinement of the coding and intron-exon junction sequences of the CACNA1A gene is also provided.
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PMID:Episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6) due to CAG repeat expansion in the CACNA1A gene on chromosome 19p. 930 78

Episodic ataxia (EA) is a rare, disabling condition of autosomal dominant inheritance, but it is not a distinct clinical entity. Synonyms are familial periodic ataxia or hereditary paroxysmal cerebellar ataxia. Family members have a similar clinical syndrome; however, the syndrome varies considerably from family to family. At least two groups of disorders have been separated clinically: (1) episodic ataxia type 1 (EA-1), which manifests without vertigo and is associated with 'interictal' myokymia, and (2) episodic ataxia type 2 (EA-2), which often manifests with vertigo and is associated with 'interictal' nystagmus. EA-1 and EA-2 have been identified as channelopathies. EA-1 is due to different heterozygous missense point mutations in a voltage-gated (delayed rectifier) potassium channel gene (KCNA1/Kv1.1) on chromosome 12p13, whereas EA-2 is caused by mutations of the cerebral P/Q-type calcium channel alpha 1 subunit gene CACNL1A4 localized on chromosome 19p, which is highly expressed in the cerebellum. The diagnosis of EA-1 and EA-2 is important, since they can be easily treated and are often mislabeled. As effective as acetazolamide is in preventing attacks, prospective studies still have to prove whether it can prevent progressive ataxia in EA-2 or even improve chronic cerebellar deficits.
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PMID:Episodic ataxia type 1 and 2 (familial periodic ataxia/vertigo). 939 Aug 41

Clinical details are given of different types of episodic ataxia: type 1, with myokymia, and attacks which usually last a few minutes, and may occur several times a day, and treatment with acetazolamide can reduce the number of attacks; type 2, with interictal nystagmus, and attacks which last for several hours to a day or more, and treatment with acetazolamide is very effective; paroxysmal choreoathetosis with episodic ataxia, with attacks lasting for about 20 min and occurring at varying intervals; and familial hemiplegic migraine, with transient hemiplegia presenting during the aura of a migraine headache, the symptoms improving on treatment with acetazolamide. Their inheritance is of dominant type; and the gene for type 1 is mapped to chromosome 12p near to a cluster of potassium channel genes, and that for type 2 and for familial hemiplegic migraine to chromosome 19p near to calcium channel genes. The differential diagnosis from other conditions with a periodic symptomatology is discussed, especially from a number of metabolic disorders. Treatment is effective for many of these, and the treatment of the episodic ataxias with acetazolamide can sometimes have a dramatic effect. The possible role of the channelopathies in the causation of some periodic neurological disorders is considered; with the expectation that further research will improve the identification of specific diseases, and lead to more effective treatment.
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PMID:Episodic ataxia and channelopathies. 953 53

Using a molecular diagnostic approach, we investigated 101 kindreds with autosomal dominant cerebellar ataxias (ADCAs) from the central Honshu island of Japan, including spinocerebellar ataxia type 1 (SCA1), spinocerebellar ataxia type 2 (SCA2), Machado-Joseph disease (MJD), dentatorubral and pallidoluysian atrophy (DRPLA) and spinocerebellar ataxia type 6 (SCA6). In our unselected series, MJD was the most common type of ADCA, accounting for 33.7% followed by DRPLA (19.8%), SCA2 (5.9%) and SCA6 (5.9%). No SCA1 mutations were identified. We analysed the clinical features of six molecular confirmed SCA6 kindreds: in each family, there was an expanded allele in the alpha1A-voltage dependent calcium channel comprising between 23 and 25 CAG repeats. The mean age at onset of symptoms was 43+/-13 years. The clinical features consisted predominantly of cerebellar ataxia, dysarthria and horizontal nystagmus, which was generally consistent with ADCA type 3. However several new clinical features were found in some patients: dramatic anticipation, rapid disease progression, severe ataxia associated with action tremor or action myoclonus, and very early onset, which are not described as the classical features of ADCA type 3.
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PMID:Frequency analysis of autosomal dominant cerebellar ataxias in Japanese patients and clinical characterization of spinocerebellar ataxia type 6. 955 Mar 56

We report on seven Japanese families with spinocerebellar ataxia type 6 (SCA6) carrying small CAG repeat expansions in the calcium channel alpha1A subunit gene. The number of the expanded CAG repeat, ranged from 22 to 25, showed no intergenerational instability and had a significant inverse correlation with the age of onset. The clinical features of these patients were late onset progressive pure cerebellar ataxia with dysarthria and nystagmus, and are consistent with autosomal dominant cerebellar ataxia type III (ADCA type III). Magnetic resonance imaging scan of the brain demonstrated cerebellar atrophy with no evidence of brainstem involvement. We propose that clinical phenotype of SCA6 is compatible with ADCA type III and SCA6 is one of the most common types of ADCA in Japan.
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PMID:Clinical and molecular genetic study in seven Japanese families with spinocerebellar ataxia type 6. 960 Jun 77

The SCA6 mutation, a small expansion of a CAG repeat in a calcium channel gene CACNA1A, was identified in three pedigrees. Point mutations in other parts of the gene CACNA1A were excluded and new clinical features of SCA6 reported--namely, central positional nystagmus and episodic ataxia responsive to acetazolamide. The three allelic disorders, episodic ataxia type 2, familial hemiplegic migraine, and SCA6, have overlapping clinical features.
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PMID:Spinocerebellar ataxia type 6 with positional vertigo and acetazolamide responsive episodic ataxia. 977 87

A 39-year-old man with episodic ataxia with nystagmus (EA-2) was reported. He showed intermittent cerebellar dysfunction, i.e., ataxia, nystagmus, dysarthria and vertigo, since he was 10 years old. Although this attack lasted for several hours, he was normal with exception of interictal nystagmus. His parents and sister showed no episodic ataxia. We ruled out the diseases, which may cause episodic ataxia, such as multiple sclerosis, vascular disorders, metabolic disorders and congenital anomalies. He was released from the attack by treatment with acetazolamide. EA-2 has been associated with mutations in the alpha 1A-voltage dependent calcium channel gene (CACNL1A4), which is also affected in familial hemiplegic migraine (FMH) and spinocerebellar ataxia type 6 (SCA6). In EA-2, frame-shift mutation leading to premature stop and splice-site mutation leading to truncated, non-functional channel protein have been reported. However, our patient did not have the mutations in the CACNL1A4 gene that were previously reported. In addition, our patient did not have an expanded CAG allele in the CACNL1A4 gene which is responsible for SCA6. Further examination is required to address whether a new mutation exists in the CACNL1A4 gene in our patient.
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PMID:[A sporadic case of episodic ataxia with nystagmus (EA-2)]. 980 92

To investigate the clinical range of spinocerebellar ataxia type 6 (SCA6), we screened CAG repeat expansion in the voltage-dependent alpha 1A calcium channel gene (CACNL1A4) in 71 ataxic patients in 60 families; 54 patients in 43 families with hereditary ataxia and 17 sporadic patients. Thirteen patients with SCA6 were detected to have elongated CAG in CACNL1A4. Of these, 7 patients had been diagnosed as having hereditary cerebellar cortical atrophy, and 6 patients had been found to have sporadic occurrence. One patient showed distinct pontine atrophy with prominent horizontal or oblique gaze nystagmus which is an unusual feature in sporadic olivopontocerebellar atrophy. For the efficient screening of SCA6, we would propose testing CAG repeat expansion in CACNL1A4, in patients with one of two markers: (1) horizontal or oblique gaze nystagmus without other eye movement disorders, (2) pure cerebellar atrophy, even if occurrence is sporadic. We should note that the pontine atrophy could also be caused by CAG repeat expansion in CACNL1A4.
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PMID:Pontine atrophy in spinocerebellar ataxia type 6. 1060 3

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


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