Genetic variations influencing nicotine receptors in the brain are linked to differing levels of cigarette consumption, according to a study published Tuesday in Nature Communications. The research identifies specific genetic variants in the CHRNB3 gene associated with a reduced number of cigarettes smoked daily.
The study, led by geneticists Veera Rajagopa and Giovanni Coppola at the Regeneron Genetic Center, analyzed data from nearly 38,000 smokers in Mexico City. Researchers discovered a deleterious missense variant, p.Glu284Gly, in the CHRNB3 gene that correlated with significantly lower daily cigarette intake. Individuals with one copy of this variant smoked, on average, 21% fewer cigarettes per day compared to those with the most common version of the gene. Those with two copies smoked approximately 78% fewer cigarettes.
To validate these findings, the team extended their analysis to genetic data from approximately 130,000 individuals in the United Kingdom and 180,000 in Japan. The association between the CHRNB3 gene variant and reduced cigarette consumption held true across all three populations – Indigenous Mexicans, East Asians, and Europeans – strengthening the evidence for a biological link, the researchers stated.
Nicotine exerts its addictive effects by binding to nicotinic acetylcholine receptors in the brain, mimicking the action of the neurotransmitter acetylcholine. This interaction triggers the release of dopamine in the brain’s reward system, creating pleasurable sensations. The CHRNB3 gene provides instructions for making a subunit of these receptors, the β3 subunit. Variations in this subunit can alter how the receptor functions and, how individuals respond to nicotine.
The study builds on previous research identifying links between variations in the CHRNB2 gene and a lower likelihood of heavy smoking. The identification of CHRNB3 as another contributing gene provides a more comprehensive understanding of the genetic factors influencing nicotine dependence.
Researchers suggest that targeting the β3 subunit of the nicotinic acetylcholine receptor could potentially lead to new therapies for nicotine addiction. “We have discovered that people carrying rare, naturally occurring mutations in a gene called CHRNB3 tend to smoke significantly fewer cigarettes per day,” Rajagopa and Coppola explained. However, they emphasize the need for further investigation, including larger studies and more precise measurements of nicotine dependence, to fully elucidate the genetic influence on smoking behavior.
The findings, published alongside other research on genetic predispositions to addiction, represent a step toward personalized approaches to smoking cessation. The study does not offer an immediate clinical solution, but it does pinpoint a potential therapeutic target for future drug development.
