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CHRNA4 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CHRNA4 gene

The CHRNA4 gene encodes the α4 subunit of nicotinic acetylcholine receptors, which are critical for neurotransmitter signaling and are linked to sleep-related epilepsy and nicotine dependence.

Normal Function

The CHRNA4 gene provides instructions for making one part (subunit) of a larger protein complex called a nicotinic acetylcholine receptor (nAChR). Each nAChR complex is made up of a combination of five subunits, usually two alpha (α) and three beta (β) subunits. Many different combinations are possible; the characteristics of each nAChR complex depend on its specific subunits. In the brain, the complex most commonly consists of two α4 subunits and three β2 subunits. The CHRNA4 gene is responsible for producing the α4 subunit.

In the brain, the nAChR complex plays an important role in chemical signaling between nerve cells (neurons). The nAChR acts as a channel, allowing charged atoms (ions), including calcium, sodium, and potassium, to cross the cell membrane. These channels open when they attach to a chemical messenger (neurotransmitter) called acetylcholine. The channels also open in response to nicotine, the addictive substance in tobacco. As these channels open, the increased flow of ions across the cell membrane alters the release of neurotransmitters.

Communication between neurons depends on neurotransmitters. 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.

Health Conditions Related to Genetic Changes

Autosomal dominant sleep-related hypermotor epilepsy

Genetic changes that cause disease or that increase the risk of disease are sometimes called mutations or pathogenic variants. Pathogenic variants in the CHRNA4 gene have been identified in people with autosomal dominant sleep-related hypermotor epilepsy (ADSHE), a genetic form of epilepsy that is characterized by seizures that typically begin while a person is sleeping and involve some degree of muscle (motor) activity. The seizures may include repetitive, abnormal muscle movements; muscle stiffness; or abnormal body positioning.

Pathogenic variants in the CHRNA4 gene can cause cells to produce subunits that make nAChR channels more sensitive to acetylcholine, which allows the channels to open more easily than usual. The resulting increase in ions crossing the cell membrane alters the release of neurotransmitters, which changes the signaling between neurons. As a result, it is likely that certain neurons are more active than usual, which triggers the abnormal brain activity associated with seizures. It is unclear why the seizures seen in people with ADSHE typically occur during sleep.

Other disorders

Several common variations (polymorphisms) in the CHRNA4 gene likely contribute to a person's risk of nicotine dependence. Cigarettes and other forms of tobacco contain nicotine, a drug that interacts with nAChR channels in the brain to produce a feeling of heightened well-being and alertness. These feelings make nicotine highly addictive.

Nicotine exerts its effects on the brain primarily by interacting with nAChR channels. Researchers have found several CHRNA4 polymorphisms that appear to lower a person’s risk of becoming addicted to nicotine. Many of these polymorphisms change a single protein building block (amino acid) in the α4 subunit of nAChR channels. These changes alter the structure of nAChR channels, which presumably affects the release and uptake of neurotransmitters in the brain.

Other Names for This Gene

  • acetylcholine receptor, neuronal nicotonic, alpha-4 subunit
  • acetylcholine receptor, nicotinic, alpha 4 (neuronal)
  • BFNC
  • cholinergic receptor, neuronal nicotinic, alpha polypeptide 4
  • cholinergic receptor, nicotinic alpha 4
  • cholinergic receptor, nicotinic, alpha 4 (neuronal)
  • EBN
  • EBN1
  • NACHR
  • NACHRA4
  • NACRA4

Frequently Asked Questions

Most pathogenic CHRNA4 variants are gain-of-function mutations located in the pore-forming regions of the α4 nicotinic receptor subunit. These changes increase the receptor's sensitivity to acetylcholine, delay channel desensitization, or increase calcium influx. This leads to excessive release of neurotransmitters and hyper-synchronous firing across frontal lobe cortical circuits, particularly during light non-REM sleep when cholinergic tone fluctuates.
CHRNA4-related epilepsy follows an autosomal dominant inheritance pattern. A person with an altered gene has a 50 percent chance of transmitting it to their offspring. However, the condition exhibits reduced penetrance, estimated around 70 to 80 percent. This means some family members who inherit the mutated gene may never experience seizures, while others may experience frequent nocturnal clusters.
Standard first-line therapy is carbamazepine or oxcarbazepine, which achieves seizure control or substantial reduction in approximately 70 percent of patients. If seizures remain refractory, adjunctive medications such as topiramate, lamotrigine, or valproate may be added. Because seizures are nocturnal, bedroom safety measures—such as placing the mattress on the floor, removing sharp bedside tables, and avoiding top bunks—are recommended to prevent physical trauma during hypermotor attacks.
Yes. The α4β2 nicotinic receptor complex is the primary mediator of nicotine addiction in the reward centers of the brain. Certain non-pathogenic polymorphisms and variations in CHRNA4 alter how strongly nicotine binds to its receptors and influences dopamine release. Studies suggest specific CHRNA4 genotypes can affect the severity of withdrawal symptoms and how effectively an individual responds to smoking cessation pharmacotherapies such as varenicline or nicotine replacement products.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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