KCNQ3

Reviewed May 2011

What is the official name of the KCNQ3 gene?

The official name of this gene is “potassium voltage-gated channel, KQT-like subfamily, member 3.”

KCNQ3 is the gene's official symbol. The KCNQ3 gene is also known by other names, listed below.

What is the normal function of the KCNQ3 gene?

The KCNQ3 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 specific function of a potassium channel depends on its protein components and its location in the body. Channels made with the KCNQ3 protein are active in nerve cells (neurons) in the brain, where they transport potassium ions out of cells. These channels transmit a particular type of electrical signal called the M-current, which prevents the neuron from continuing to send signals to other neurons. The M-current ensures that the neuron is not constantly active, or excitable.

Potassium channels are made up of several protein components (subunits). Each channel contains four alpha subunits that form the hole (pore) through which potassium ions move. Four alpha subunits from the KCNQ3 gene can form a channel. However, the KCNQ3 alpha subunits can also interact with alpha subunits from the KCNQ2 gene to form a functional potassium channel, and these channels transmit a much stronger M-current.

Does the KCNQ3 gene share characteristics with other genes?

The KCNQ3 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 KCNQ3 gene related to health conditions?

benign familial neonatal seizures - caused by mutations in the KCNQ3 gene: A mutation in the KCNQ3 gene has been identified in some people with benign familial neonatal seizures (BFNS), a condition characterized by recurrent seizures in newborn babies. The seizures begin around day 3 of life and usually go away within 1 to 4 months. At least three mutations have been identified in people with this condition, and these mutations change single protein building blocks (amino acids) in the KCNQ3 protein. As a result of these mutations, the M-current is reduced. Researchers believe that a reduction of the current by 25 percent is enough to cause BFNS. A reduced M-current leads to excessive excitability of neurons, which is known to cause seizures. It is unclear why the seizures stop around the age of 4 months. It has been suggested that potassium channels formed from the KCNQ2 and KCNQ3 proteins play a major role in preventing excessive excitability of neurons in newborns, but other mechanisms develop during infancy.

Where is the KCNQ3 gene located?

Cytogenetic Location: 8q24

Molecular Location on chromosome 8: base pairs 133,133,104 to 133,493,003

The KCNQ3 gene is located on the long (q) arm of chromosome 8 at position 24.

More precisely, the KCNQ3 gene is located from base pair 133,133,104 to base pair 133,493,003 on chromosome 8.

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 KCNQ3?

You and your healthcare professional may find the following resources about KCNQ3 helpful.

Educational resources - Information pages
Biochemistry (5th Edition, 2002): Action Potentials are Mediated by Transient Changes in Na+ and K+ Permeability (http://www.ncbi.nlm.nih.gov/books/NBK22509/)
Gene Reviews - Clinical summary (http://www.ncbi.nlm.nih.gov/books/NBK32534/)
Genetic Testing Registry - Repository of genetic test information
- GTR: Genetic tests for KCNQ3 (http://www.ncbi.nlm.nih.gov/gtr/tests/?term=3786%5Bgeneid%5D)

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

PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/pubmed?term=(KCNQ3%5BTIAB%5D)%20AND%20((Genes%5BMH%5D)%20OR%20(Genetic%20Phenomena%5BMH%5D))%20AND%20english%5Bla%5D%20AND%20human%5Bmh%5D%20AND%20%22last%201800%20days%22%5Bdp%5D)
OMIM - Genetic disorder catalog (http://omim.org/entry/602232)
Research Resources - Tools for researchers
- Atlas of Genetics and Cytogenetics in Oncology and Haematology (http://atlasgeneticsoncology.org/Genes/GC_KCNQ3.html)
- Entrez Gene (http://www.ncbi.nlm.nih.gov/gene/3786)
- GeneCards (http://www.genecards.org/cgi-bin/carddisp.pl?id_type=entrezgene&id=3786)
- HUGO Gene Nomenclature Committee (http://www.genenames.org/data/hgnc_data.php?hgnc_id=6297)

What other names do people use for the KCNQ3 gene or gene products?

BFNC2
EBN2
KCNQ3_HUMAN
KV7.3
potassium channel subunit alpha KvLQT3
potassium channel, voltage-gated, subfamily Q, member 3
potassium voltage-gated channel subfamily KQT member 3
voltage-gated potassium channel subunit Kv7.3

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 KCNQ3?

acids ; benign ; cell ; channel ; familial ; gene ; ions ; mutation ; neonatal ; neuron ; 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

Chung HJ, Jan YN, Jan LY. Polarized axonal surface expression of neuronal KCNQ channels is mediated by multiple signals in the KCNQ2 and KCNQ3 C-terminal domains. Proc Natl Acad Sci U S A. 2006 Jun 6;103(23):8870-5. Epub 2006 May 30. (http://www.ncbi.nlm.nih.gov/pubmed/16735477?dopt=Abstract)
Entrez Gene (http://www.ncbi.nlm.nih.gov/gene/3786)
OMIM: POTASSIUM CHANNEL, VOLTAGE-GATED, KQT-LIKE SUBFAMILY, MEMBER 3 (http://omim.org/entry/602232)
Rogawski MA. KCNQ2/KCNQ3 K+ channels and the molecular pathogenesis of epilepsy: implications for therapy. Trends Neurosci. 2000 Sep;23(9):393-8. Review. (http://www.ncbi.nlm.nih.gov/pubmed/10941184?dopt=Abstract)
Schroeder BC, Kubisch C, Stein V, Jentsch TJ. Moderate loss of function of cyclic-AMP-modulated KCNQ2/KCNQ3 K+ channels causes epilepsy. Nature. 1998 Dec 17;396(6712):687-90. (http://www.ncbi.nlm.nih.gov/pubmed/9872318?dopt=Abstract)
Singh NA, Westenskow P, Charlier C, Pappas C, Leslie J, Dillon J, Anderson VE, Sanguinetti MC, Leppert MF; BFNC Physician Consortium. KCNQ2 and KCNQ3 potassium channel genes in benign familial neonatal convulsions: expansion of the functional and mutation spectrum. Brain. 2003 Dec;126(Pt 12):2726-37. Epub 2003 Oct 8. (http://www.ncbi.nlm.nih.gov/pubmed/14534157?dopt=Abstract)
Soldovieri MV, Miceli F, Bellini G, Coppola G, Pascotto A, Taglialatela M. Correlating the clinical and genetic features of benign familial neonatal seizures (BFNS) with the functional consequences of underlying mutations. Channels (Austin). 2007 Jul-Aug;1(4):228-33. Epub 2007 Aug 2. (http://www.ncbi.nlm.nih.gov/pubmed/18698150?dopt=Abstract)
Wang HS, Pan Z, Shi W, Brown BS, Wymore RS, Cohen IS, Dixon JE, McKinnon D. KCNQ2 and KCNQ3 potassium channel subunits: molecular correlates of the M-channel. Science. 1998 Dec 4;282(5395):1890-3. (http://www.ncbi.nlm.nih.gov/pubmed/9836639?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.