The CHRNB2 gene provides instructions for making one part (subunit) of a larger protein called a neuronal nicotinic acetylcholine receptor (nAChR). Each nAChR protein is made up of a combination of five subunits, usually two alpha (α) and three beta (β) subunits. Many different combinations are possible, and the characteristics of each nAChR protein depend on which subunits it contains. In the brain, nAChR proteins most commonly consist of two α4 subunits and three β2 subunits. The CHRNB2 gene is responsible for producing the β2 subunit.
In the brain, nAChR proteins are widely distributed and play an important role in chemical signaling between nerve cells (neurons). The nAChR proteins act as channels, allowing charged atoms (ions) including calcium, sodium, and potassium to cross the cell membrane. These channels open when attached to a brain chemical (neurotransmitter) called acetylcholine. The channels also open in response to nicotine, the addictive substance in tobacco.
Communication between neurons depends on neurotransmitters, which are released from one neuron and taken up by neighboring neurons. The release and uptake of these chemicals are tightly regulated to ensure that signals are passed efficiently and accurately between neurons. Researchers believe that nAChR channels play an important role in controlling the normal release and uptake of neurotransmitters.
A wide range of brain functions depend on nAChR channels, including sleep and arousal, fatigue, anxiety, attention, pain perception, and memory. The channels are also active before birth, which suggests that they are involved in early brain development. At least one drug that targets nAChR channels in the brain has been developed to help people quit smoking; other medications targeting these channels are under study for the treatment of schizophrenia, Alzheimer disease, and pain.
Health Conditions Related to Genetic Changes
Autosomal dominant nocturnal frontal lobe epilepsy
At least three mutations in the CHRNB2 gene have been identified in people with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE). Each of these mutations changes a single protein building block (amino acid) in the β2 subunit of nAChR channels.
CHRNB2 mutations make nAChR channels more sensitive to the neurotransmitter acetylcholine, allowing the channels to open more easily than usual. The resulting increase in ion flow across the cell membrane alters the release of neurotransmitters, which changes signaling between neurons. Researchers believe that the overexcitement of certain neurons in the brain triggers the abnormal brain activity associated with seizures. It is unclear why the seizures seen in ADNFLE start in the frontal lobes of the brain and occur most often during sleep.More About This Health Condition
Other Names for This Gene
- Acetylcholine receptor, neuronal nicotinic, beta-2 subunit
- cholinergic receptor, nicotinic beta 2
- cholinergic receptor, nicotinic, beta 2 (neuronal)
- cholinergic receptor, nicotinic, beta polypeptide 2 (neuronal)
- neuronal nicotinic acetylcholine receptor beta 2
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
- Arneric SP, Holladay M, Williams M. Neuronal nicotinic receptors: a perspective on two decades of drug discovery research. Biochem Pharmacol. 2007 Oct 15;74(8):1092-101. Epub 2007 Jun 26. Review. Citation on PubMed
- Bertrand D, Elmslie F, Hughes E, Trounce J, Sander T, Bertrand S, Steinlein OK. The CHRNB2 mutation I312M is associated with epilepsy and distinct memory deficits. Neurobiol Dis. 2005 Dec;20(3):799-804. Epub 2005 Jun 17. Citation on PubMed
- Bertrand D, Picard F, Le Hellard S, Weiland S, Favre I, Phillips H, Bertrand S, Berkovic SF, Malafosse A, Mulley J. How mutations in the nAChRs can cause ADNFLE epilepsy. Epilepsia. 2002;43 Suppl 5:112-22. Citation on PubMed
- Bertrand S, Weiland S, Berkovic SF, Steinlein OK, Bertrand D. Properties of neuronal nicotinic acetylcholine receptor mutants from humans suffering from autosomal dominant nocturnal frontal lobe epilepsy. Br J Pharmacol. 1998 Oct;125(4):751-60. Citation on PubMed or Free article on PubMed Central
- De Fusco M, Becchetti A, Patrignani A, Annesi G, Gambardella A, Quattrone A, Ballabio A, Wanke E, Casari G. The nicotinic receptor beta 2 subunit is mutant in nocturnal frontal lobe epilepsy. Nat Genet. 2000 Nov;26(3):275-6. Citation on PubMed
- di Corcia G, Blasetti A, De Simone M, Verrotti A, Chiarelli F. Recent advances on autosomal dominant nocturnal frontal lobe epilepsy: "understanding the nicotinic acetylcholine receptor (nAChR)". Eur J Paediatr Neurol. 2005;9(2):59-66. Review. Citation on PubMed
- Hoda JC, Gu W, Friedli M, Phillips HA, Bertrand S, Antonarakis SE, Goudie D, Roberts R, Scheffer IE, Marini C, Patel J, Berkovic SF, Mulley JC, Steinlein OK, Bertrand D. Human nocturnal frontal lobe epilepsy: pharmocogenomic profiles of pathogenic nicotinic acetylcholine receptor beta-subunit mutations outside the ion channel pore. Mol Pharmacol. 2008 Aug;74(2):379-91. doi: 10.1124/mol.107.044545. Epub 2008 May 2. Citation on PubMed
- Marini C, Guerrini R. The role of the nicotinic acetylcholine receptors in sleep-related epilepsy. Biochem Pharmacol. 2007 Oct 15;74(8):1308-14. Epub 2007 Jun 23. Review. Citation on PubMed
- Phillips HA, Favre I, Kirkpatrick M, Zuberi SM, Goudie D, Heron SE, Scheffer IE, Sutherland GR, Berkovic SF, Bertrand D, Mulley JC. CHRNB2 is the second acetylcholine receptor subunit associated with autosomal dominant nocturnal frontal lobe epilepsy. Am J Hum Genet. 2001 Jan;68(1):225-31. Epub 2000 Dec 5. Citation on PubMed or Free article on PubMed Central