Episodic ataxia

About: Episodic ataxia is a research topic. Over the lifetime, 425 publications have been published within this topic receiving 21012 citations.

Autosomal dominant cerebellar ataxia (SCA6) associated with small polyglutamine expansions in the α(1A)-voltage-dependent calcium channel

Abstract: A polymorphic CAG repeat was identified in the human α1A voltage-dependent calcium channel subunit. To test the hypothesis that expansion of this CAG repeat could be the cause of an inherited progressive ataxia, we genotyped a large number of unrelated controls and ataxia patients. Eight unrelated patients with late onset ataxia had alleles with larger repeat numbers (21‐27) compared to the number of repeats (4‐16) in 475 non‐ataxia individuals. Analysis of the repeat length in families of the affected individuals revealed that the expansion segregated with the phenotype in every patient. We identified six isoforms of the human α1A calcium channel subunit. The CAG repeat is within the open reading frame and is predicted to encode glutamine in three of the isoforms. We conclude that a small polyglutamine expansion in the human α1A calcium channel is most likely the cause of a newly classified autosomal dominant spinocerebellar ataxia, SCA6.

Episodic ataxia/myokymia syndrome is associated with point mutations in the human potassium channel gene, KCNA1.

Abstract: Episodic ataxia (EA) is a rare, familial disorder producing attacks of generalized ataxia, with normal or near-normal neurological function between attacks. One type of EA is characterized by brief episodes of ataxia with myokymia (rippling of muscles) evident between attacks. Linkage studies in four such families suggested localization of an EA/myokymia gene near the voltage gated K+ channel gene, KCNA1 (Kv1.1), on chromosome 12p. Mutation analysis of the KCNA1 coding region in these families identified four different missense point mutations present in the heterozygous state, indicating that EA/myokymia can result from mutations in this gene.

Voltage-Gated Ion Channels and Hereditary Disease

Abstract: By the introduction of technological advancement in methods of structural analysis, electronics, and recombinant DNA techniques, research in physiology has become molecular Additionally, focus of interest has been moving away from classical physiology to become increasingly centered on mechanisms of disease A wonderful example for this development, as evident by this review, is the field of ion channel research which would not be nearly as advanced had it not been for human diseases to clarify It is for this reason that structure-function relationships and ion channel electrophysiology cannot be separated from the genetic and clinical description of ion channelopathies Unique among reviews of this topic is that all known human hereditary diseases of voltage-gated ion channels are described covering various fields of medicine such as neurology (nocturnal frontal lobe epilepsy, benign neonatal convulsions, episodic ataxia, hemiplegic migraine, deafness, stationary night blindness), nephrology (X-linked recessive nephrolithiasis, Bartter), myology (hypokalemic and hyperkalemic periodic paralysis, myotonia congenita, paramyotonia, malignant hyperthermia), cardiology (LQT syndrome), and interesting parallels in mechanisms of disease emphasized Likewise, all types of voltage-gated ion channels for cations (sodium, calcium, and potassium channels) and anions (chloride channels) are described together with all knowledge about pharmacology, structure, expression, isoforms, and encoding genes

Potassium Channels: Molecular Defects, Diseases, and Therapeutic Opportunities

Abstract: Potassium channels play important roles in vital cellular signaling processes in both excitable and nonexcitable cells. Over 50 human genes encoding various K(+) channels have been cloned during the past decade, and precise biophysical properties, subunit stoichiometry, channel assembly, and modulation by second messenger and ligands have been elucidated to a large extent. Recent advances in genetic linkage analysis have greatly facilitated the identification of many disease-producing loci, and naturally occurring mutations in various K(+) channels have been identified in diseases such as long-QT syndromes, episodic ataxia/myokymia, familial convulsions, hearing and vestibular diseases, Bartter's syndrome, and familial persistent hyperinsulinemic hypoglycemia of infancy. In addition, changes in K(+) channel function have been associated with cardiac hypertrophy and failure, apoptosis and oncogenesis, and various neurodegenerative and neuromuscular disorders. This review aims to 1) provide an understanding of K(+) channel function at the molecular level in the context of disease processes and 2) discuss the progress, hurdles, challenges, and opportunities in the exploitation of K(+) channels as therapeutic targets by pharmacological and emerging genetic approaches.