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Normal Function
The KCNA1 gene belongs to a large family of genes that provide instructions for making potassium channels. These channels, which transport positively charged potassium atoms (potassium ions) 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.
Health Conditions Related to Genetic Changes
Episodic ataxia
Many variants (also called 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 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 variants that cause 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 variants 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 the brain's signals cause 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.
More About This Health ConditionOther disorders
Variants in the KCNA1 gene have been found to cause a range of signs and symptoms that affect the nervous system. In at least one family, isolated myokymia (continuous muscle twitching and spasms without episodes of ataxia) has been attributed to KCNA1 variants. Changes in this gene have also been identified in a small number of people with repeated seizures (epilepsy). Like the KCNA1 variants that cause episodic ataxia (described above), the variants 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 variants in this single gene can cause several different disorders of the nervous system.
Other Names for This Gene
- AEMK
- EA1
- HBK1
- HUK1
- KCNA1_HUMAN
- KV1.1
- MBK1
- MGC126782
- MGC138385
- MK1
- potassium channel, voltage gated shaker related subfamily A, member 1
- potassium voltage-gated channel, shaker-related subfamily, member 1 (episodic ataxia with myokymia)
- RBK1
- voltage-gated potassium channel subunit Kv1.1
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
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. doi: 10.1038/ng1094-136. Citation on PubMed
- 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. doi: 10.1007/s10048-006-0071-z. Epub 2006 Nov 29. Citation on PubMed or Free article on PubMed Central
- 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. Citation on PubMed
- 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. doi: 10.1093/brain/awm126. Epub 2007 Jun 15. Citation on PubMed
- 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. doi: 10.1523/JNEUROSCI.22-12-04786.2002. Citation on PubMed
- Rajakulendran S, Schorge S, Kullmann DM, Hanna MG. Episodic ataxia type 1: a neuronal potassium channelopathy. Neurotherapeutics. 2007 Apr;4(2):258-66. doi: 10.1016/j.nurt.2007.01.010. Citation on PubMed
- 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. doi: 10.1113/jphysiol.2001.013242. Citation on PubMed or Free article on PubMed Central
- 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. doi: 10.1523/JNEUROSCI.18-08-02842.1998. Citation on PubMed
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