title: Associations of CYP2A6 genotype with smoking behaviors in southern China.
abstract: OBJECTIVE
  To investigate the association of CYP2A6 genetic polymorphisms with smoking-related phenotypes in Chinese smokers.
  
  
  METHODS
  Case-only genetic association study.
  
  
  METHODS
  Southern China.
  
  
  METHODS
  A total of 1328 Han Chinese smokers who participated in a community-based chronic disease screening project in Guangzhou and Zhuhai from 2006 to 2007.
  
  
  METHODS
  All participants answered a structured questionnaire about socio-demographic status and smoking behaviors and informative alleles were genotyped for the cytochrome P450 2A6 (CYP2A6) gene (CYP2A6*4,*5,*7,*9 and *10).
  
  
  RESULTS
  The frequencies of CYP2A6*4, *5, *7, *9 and *10 alleles were 8.5, 1.2, 6.3, 13.5 and 2.4%, which corresponded to 48.9, 15.4, 24.2 and 11.5% of participants being classified as normal, intermediate, slow and poor metabolizers, respectively. Multivariate analyses in male smokers demonstrated that compared with normal metabolizers, poor metabolizers reported smoking fewer cigarettes per day [adjusted odds ratio (OR) = 0.49; 95% confidence interval (CI): 0.32-0.76], started smoking regularly later in life (adjusted OR = 1.55; 95% CI: 1.06-2.26) and, among former smokers, reported smoking for a shorter duration prior to quitting (adjusted OR = 0.33; 95% CI: 0.12-0.94). However, poor metabolizers were less likely to quit smoking and remain abstinent than normal metabolizers (adjusted OR = 0.54; 95% CI: 0.34-0.86).
  
  
  CONCLUSIONS
  Reduced metabolism function of cytochrome P450 2A6 in smokers appears to be associated with fewer cigarettes smoked, later initiation of smoking regularly, shorter smoking duration and lower likelihood of smoking cessation.
authors.affiliation: Department of Biostatistics and Epidemiology, School of Public Health, Sun Yat-Sen University, Guangzhou, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Sean P
authors.initials: SP
authors.lastname: David
authors.forename: Rachel F
authors.initials: RF
authors.lastname: Tyndale
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.forename: Peng
authors.initials: P
authors.lastname: Ding
authors.forename: Yan-Hui
authors.initials: YH
authors.lastname: He
authors.forename: Xue-Qing
authors.initials: XQ
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Casey
authors.initials: C
authors.lastname: Crump
authors.forename: Xiao-Zhong
authors.initials: XZ
authors.lastname: Wen
authors.forename: Wei-Qing
authors.initials: WQ
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics*; D044466:Asian People / Q000235:genetics; D002681:China / Q000453:epidemiology; D065637:Cytochrome P-450 CYP2A6; D004812:Epidemiologic Methods; D005260:Female; D005787:Gene Frequency / Q000235:genetics*; D056726:Genetic Association Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009538:Nicotine / Q000378:metabolism; D018722:Nicotinic Agonists / Q000378:metabolism; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012907:Smoking / Q000453:epidemiology / Q000235:genetics*; D016540:Smoking Cessation / Q000706:statistics & numerical data; D012959:Socioeconomic Factors; D013997:Time Factors; D055815:Young Adult
chemical_list: D018722:Nicotinic Agonists; D009538:Nicotine; D001189:Aryl Hydrocarbon Hydroxylases; C585710:CYP2A6 protein, human; D065637:Cytochrome P-450 CYP2A6