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Genetics Home Reference: your guide to understanding genetic conditions
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KCNA1

Reviewed August 2008

What is the official name of the KCNA1 gene?

The official name of this gene is “potassium voltage-gated channel, shaker-related subfamily, member 1 (episodic ataxia with myokymia).”

KCNA1 is the gene's official symbol. The KCNA1 gene is also known by other names, listed below.

What is the normal function of the KCNA1 gene?

The KCNA1 gene belongs to a large family of genes that provide instructions for making potassium channels. These channels, which transport positively charged atoms (ions) of potassium into and out of cells, play a key role in a cell's ability to generate and transmit electrical signals.

The KCNA1 gene provides instructions for making one part (the alpha subunit) of a potassium channel called Kv1.1. These channels are found in the brain, where they transport potassium ions into nerve cells (neurons). The flow of certain ions, including potassium, into and out of neurons regulates communication between these cells.

Does the KCNA1 gene share characteristics with other genes?

The KCNA1 gene belongs to a family of genes called KCN (potassium channels).

A gene family is a group of genes that share important characteristics. Classifying individual genes into families helps researchers describe how genes are related to each other. For more information, see What are gene families? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genefamilies) in the Handbook.

How are changes in the KCNA1 gene related to health conditions?

episodic ataxia - caused by mutations in the KCNA1 gene

At least 20 mutations in the KCNA1 gene have been identified in people with episodic ataxia type 1 (EA1). People with this form of the condition have brief, recurrent episodes of poor coordination and balance (ataxia). Between episodes, many affected individuals experience myokymia, a muscle abnormality that can cause involuntary muscle cramping, stiffness, and continuous, fine muscle twitching that appears as rippling under the skin.

Most of the KCNA1 mutations responsible for episodic ataxia change single protein building blocks (amino acids) in the alpha subunit of the Kv1.1 channel. Some of these changes prevent the assembly of functional channels, while other mutations alter the channel's structure. When Kv1.1 channels are missing or abnormal, the flow of potassium ions into neurons is reduced. This decrease in potassium ions overexcites certain neurons in the brain, which disrupts normal communication between these cells. Although changes in signaling between neurons underlie the episodes of uncoordinated movement seen in people with episodic ataxia, it is unclear how altered potassium ion transport causes the specific features of the condition.

other disorders - caused by mutations in the KCNA1 gene

Mutations in the KCNA1 gene have been found to cause a range of signs and symptoms affecting the nervous system. In at least one family, isolated myokymia (continuous muscle twitching and spasms without episodes of ataxia) has been attributed to KCNA1 mutations. Changes in this gene have also been identified in a small number of people with epilepsy. Like the KCNA1 mutations that underlie episodic ataxia, the mutations that cause isolated myokymia and epilepsy reduce the flow of potassium ions through Kv1.1 channels, disrupting normal communication between neurons in the brain. Researchers are working to determine why mutations in this single gene can cause several different disorders of the nervous system.

Where is the KCNA1 gene located?

Cytogenetic Location: 12p13.32

Molecular Location on chromosome 12: base pairs 4,909,906 to 4,918,255

The KCNA1 gene is located on the short (p) arm of chromosome 12 at position 13.32.

The KCNA1 gene is located on the short (p) arm of chromosome 12 at position 13.32.

More precisely, the KCNA1 gene is located from base pair 4,909,906 to base pair 4,918,255 on chromosome 12.

See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.

Where can I find additional information about KCNA1?

You and your healthcare professional may find the following resources about KCNA1 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the KCNA1 gene or gene products?

  • AEMK
  • EA1
  • HBK1
  • HUK1
  • KCNA1_HUMAN
  • KV1.1
  • MBK1
  • MGC126782
  • MGC138385
  • MK1
  • potassium voltage-gated channel subfamily A member 1
  • RBK1
  • voltage-gated potassium channel subunit Kv1.1

See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.

What glossary definitions help with understanding KCNA1?

acids ; ataxia ; cell ; channel ; epilepsy ; gene ; involuntary ; ions ; ion transport ; nervous system ; potassium ; protein ; subunit ; voltage

You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/glossary).

References

  • Browne DL, Gancher ST, Nutt JG, Brunt ER, Smith EA, Kramer P, Litt M. Episodic ataxia/myokymia syndrome is associated with point mutations in the human potassium channel gene, KCNA1. Nat Genet. 1994 Oct;8(2):136-40. (http://www.ncbi.nlm.nih.gov/pubmed/7842011?dopt=Abstract)
  • Chen H, von Hehn C, Kaczmarek LK, Ment LR, Pober BR, Hisama FM. Functional analysis of a novel potassium channel (KCNA1) mutation in hereditary myokymia. Neurogenetics. 2007 Apr;8(2):131-5. Epub 2006 Nov 29. (http://www.ncbi.nlm.nih.gov/pubmed/17136396?dopt=Abstract)
  • Eunson LH, Rea R, Zuberi SM, Youroukos S, Panayiotopoulos CP, Liguori R, Avoni P, McWilliam RC, Stephenson JB, Hanna MG, Kullmann DM, Spauschus A. Clinical, genetic, and expression studies of mutations in the potassium channel gene KCNA1 reveal new phenotypic variability. Ann Neurol. 2000 Oct;48(4):647-56. (http://www.ncbi.nlm.nih.gov/pubmed/11026449?dopt=Abstract)
  • Jen JC, Graves TD, Hess EJ, Hanna MG, Griggs RC, Baloh RW; CINCH investigators. Primary episodic ataxias: diagnosis, pathogenesis and treatment. Brain. 2007 Oct;130(Pt 10):2484-93. Epub 2007 Jun 15. Review. (http://www.ncbi.nlm.nih.gov/pubmed/17575281?dopt=Abstract)
  • Maylie B, Bissonnette E, Virk M, Adelman JP, Maylie JG. Episodic ataxia type 1 mutations in the human Kv1.1 potassium channel alter hKvbeta 1-induced N-type inactivation. J Neurosci. 2002 Jun 15;22(12):4786-93. (http://www.ncbi.nlm.nih.gov/pubmed/12077175?dopt=Abstract)
  • NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/3736)
  • Rajakulendran S, Schorge S, Kullmann DM, Hanna MG. Episodic ataxia type 1: a neuronal potassium channelopathy. Neurotherapeutics. 2007 Apr;4(2):258-66. Review. (http://www.ncbi.nlm.nih.gov/pubmed/17395136?dopt=Abstract)
  • Rea R, Spauschus A, Eunson LH, Hanna MG, Kullmann DM. Variable K(+) channel subunit dysfunction in inherited mutations of KCNA1. J Physiol. 2002 Jan 1;538(Pt 1):5-23. (http://www.ncbi.nlm.nih.gov/pubmed/11773313?dopt=Abstract)
  • Zerr P, Adelman JP, Maylie J. Episodic ataxia mutations in Kv1.1 alter potassium channel function by dominant negative effects or haploinsufficiency. J Neurosci. 1998 Apr 15;18(8):2842-8. (http://www.ncbi.nlm.nih.gov/pubmed/9526001?dopt=Abstract)

 

The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.

 
Reviewed: August 2008
Published: December 16, 2014