A study drawing on data from more than 32,000 African Americans and 50 institutions around the country suggests a specific gene variant is correlated with how much a person smokes. The findings were published today in Translational Psychiatry.
For the study, Sean David, MD, DPhil, a clinical associate professor of medicine here, teamed with scientists in charge of 13 previous studies around the country to create the Study of Tobacco in Minority Populations, or STOMP, Genetics Consortium. As a result, researchers were able to gather a population large enough to find statistically relevant genes.
Researchers gathered data on whether participants had ever smoked, the age they began smoking, how many cigarettes per day they smoked and whether they had successfully quit smoking. Each study sequenced the genomes of their own participants, but all used similar methods and performed the same analysis. As described in our release:
What the team discovered when they parsed all the data was one gene marker that was correlated with the number of cigarettes someone smoked per day. The marker is in the gene CHRNA5, which has also been found to be important in smoking behaviors of people of European ancestry. However, the marker is in a different spot of the gene.
CHRNA5 encodes a nicotine receptor subunit. Nicotine receptors, which bind the chemicals in cigarettes and transmit signals through the brain in response, are made up of different combinations of five subunits. Previous research by other investigators has shown that inactivating CHRNA5 in mice reduces the inhibitory, aversive effects of nicotine, such as increased heart rate and nervousness. Without these negative effects limiting their nicotine intake, the animals seek more of the chemical than usual. This reaction could explain why certain variants of the gene influence people’s smoking habits.
The team also found other genetic markers that had weaker correlations with smoking behaviors. None were statistically significant in the current study, but David said some approached genome-wide statistical significance, and they could be pursued further in the future.
David added, "Knowing that this gene is important in different ancestral groups really points to its importance and suggests it as a target for drug discovery and development."
Previously: Report shows African-American, low-income children in California at highest risk of secondhand smoke and Menthol cigarette marketing aimed at young African Americans
Photo by Egor Korotkov