- FRIDAY, Aug. 8 (HealthDay News) — A gene variant that may
influence a person's initial response to smoking and lifetime smoking
habits has been identified by a team of researchers.

The finding about the variant in the CHRNA5 nicotine receptor gene may
help explain how someone goes from trying their first cigarette to
becoming a long-term smoker.

Previous studies have inked variations in the same genetic region to a
smoker's level of nicotine dependence, to the number of cigarettes smoker
per day, and to an increased risk of lung cancer.

This new University of Michigan-led study examined genetic and smoking
data from 435 people, including never-smokers — who tried at least one
cigarette but no more than 100 cigarettes in their lives — and regular
smokers who'd smoked at least five cigarettes a day for at least the past
five years.

The regular smokers were far more likely than never-smokers to have
less common form of the CHRNA5 gene in which just one base pair in the
gene sequence is different from the more common form of the gene. Smokers
were also eight times more likely than never-smokers to have got a
pleasurable buzz when they tried their first cigarette.

The study was published online Aug. 8 in the journal
Addiction.

“It appears that for people who have a certain genetic makeup, the
initial physical reaction to smoking can play a significant role in
determining what happens next,” senior author Ovide Pomerleau, a professor
of psychiatry at the University of Michigan Medical School and founder of
the U-M Nicotine Research Laboratory, said in a prepared statement.

“If cigarette smoking is sustained, nicotine addiction can occur in a
few days to a few months. The finding of a genetic association with
pleasurable early smoking experiences may help explain how people get
addicted — and, of course, once addicted, many will keep smoking for the
rest of their lives,” he said.

The variant (rs16969968) of the CHRNA5 gene identified in this study
explains only a portion of smoking behavior, noted Pomerleau and
colleagues. More information about how genes interact with social
influences and other environmental factors is needed to achieve a more
complete explanation of why people smoke and why it's so difficult to
quit.

Making a connection between behavioral patterns in smoking to
individual genotypes will require analysis of extensive data about
behavior, genes and environmental influences, Pomerleau said.

More information

The U.S. Centers for Disease Control and Prevention has more about smoking and tobacco
use.