Genetic Variations Influence Nicotine Addiction For Young Smokers
July 11th, 2008 | by admin |
Agroup of common genetics variants that affect the nicotine receptors inthe nervous system could significantly increase the risk of developingnicotine addiction. These results, which could have powerfulimplications for policy preventing tobacco use in young people, werepublished on July 11, 2008 in the open-access journal PLoSGenetics.
Singlenucleotide polymorphisms (SNPs) are variations in the genetic sequencethat involve a single unit of DNA. A haplotype is a set of SNPs thatare often linked together.
To study the effects of varioushaplotypes on nicotine addiction, the researchers, from the Universityof Utah and the University of Wisconsin, examined 2,827 long-termEuropean American smokers in Utah and Wisconsin in the National Heart,Lung, and Blood Institute’s Lung Health Study. The level of nicotinedependence for each subject was evaluated, along with the age theybegan smoking daily, the number of years they smoked, and the averagenumber of cigarettes each smoked daily. Additionally, DNA samples werecollected from all smokers, and the occurrence of several common SNPs,which had already been grouped into haplotypes,which had beenpreviously identified in a subset of the participants.
Onehaplotype related to the nicotine receptor in neurons put EuropeanAmerican smokers at a greater risk of heavy nicotine dependence asadults if they began smoking daily before reaching 17 years.Specifically, people who began smoking before 17 years with two copiesof this haplotype had between a 1.6- and 5-fold increase in risk ofheavy smoking as an adult. This haplotype did not significantlyincrease the risk of addiction in adulthood for those who began smokingdaily after reaching 17 years. A second haplotype instead reduced therisk of heavy nicotine dependence as an adult for those one smoked as ayouth.
This genetic influence is likely valid despite thepossible confounding ethnicity of the addicted smokers. According tolead author Robert Weiss, Ph.D., professorof human genetics at the University of Utah, says: “We know that peoplewho begin smoking at a young age aremore likely to face severe nicotine dependence later in life. Thisfinding suggests that genetic influences expressed during adolescencecontribute to the risk of lifetime addiction severity produced from theearly onset of tobacco use.”
Accordingto Dr. Nora Volkow, Director of the National Institute on Drug Abuse(NIDA), points out that this is an important study investigating theinteractions of genetic factors with individual behaviors. “Thisstudy adds to recent advances in understanding how genetic variationcan affect susceptibility to nicotine addiction, success or failure ofsmokingcessation treatments, and the risk of disease associated with tobaccouse,” she says. “As we learn more about how both genes and environmentplay a role insmoking, we will be able to better tailor both prevention and cessationprograms to individuals.”
A Candidate Gene Approach Identifies the CHRNA5-A3-B4 Regionas a Risk Factor for Age-Dependent Nicotine Addiction.
Weiss RB, Baker TB, Cannon DS, von Niederhausern A, Dunn DM, et al.
PLoS Genet 4(7): e1000125.
doi:10.1371/journal.pgen.1000125
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Written by Anna Sophia McKenney
Copyright: Medical News Today
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