A genetic variant has been identified that predisposes people to smoke less.

BarcelonaThe fight against tobacco is the major challenge for healthcare systems, which allocate millions of euros to treatments. In fact, smoking remains one of the leading causes of death globally, and in Catalonia alone, 10,000 smokers die each year, a figure that rises to seven million worldwide. Now, researchers may have found a way to develop a new strategy against this addiction if it is confirmed that a rare genetic variant predisposes individuals to smoke less. By what proportion? Between 21% and 78% fewer cigarettes, according to a study published this Tuesday in the journal Nature communications.

The variation is located in the CHRNB3 gene—involved in the brain's response to nicotine—and has been found primarily in people of Mexican indigenous descent, although it has also been found in other origins in exceptional cases. Therefore, the research has focused on sequencing the genome of more than 37,000 smokers of Mexican origin who participated in the Mexico City Prospective Study to analyze the effects on their health. The research establishes that people carrying the gene variation smoke 21% less than those with the more common version, a figure equivalent to one fewer cigarette per day. However, if the variation is present in two copies of the gene, they smoke even less, up to 78%. The study, led by the Regeneron Genetics Center, highlights that variants in the genes that code for nicotinic acetylcholine receptors (which utilize the rewarding effects of this substance in the brain) have been linked to changes in smokers' behavior. Specifically, variants in a gene called CHRNB2, which codes for subunit 2 of these receptors (there are at least nine types), have been associated with a lower likelihood of excessive smoking. According to the authors, this discovery could pave the way for the development of new, targeted drugs against tobacco addiction. Unlike other current treatments, this approach could reduce the amount consumed by regular smokers. Validation in Asia and Europe

The current study, which also involved the National Autonomous University of Mexico, indicates that genetic variants affecting CHRNB3 activity can reduce the number of cigarettes smoked daily by individuals in several ancestral lineages. Subsequently, the research results were validated in populations of Asian and European ancestry, and similar effects related to CHRNB3 variants were found in populations of approximately 130,000 people of European ancestry from the UK Biobank and approximately 180,000 people of East Asian Japanese ancestry from the same biobank. With this finding, the researchers suggest that inhibiting subunit 3 may be a potential therapeutic strategy for nicotine addiction. However, the authors point out that larger cohorts and more robust research on clinical measures of nicotine dependence will be necessary to fully assess the relationship between these variants and tobacco dependence.