title: Association of functional catechol O-methyl transferase (COMT) Val108Met polymorphism with smoking severity and age of smoking initiation in Chinese male smokers.
abstract: BACKGROUND
  Catechol-O-methyltransferase (COMT) is an enzyme involved in the degradation and inactivation of the neurotransmitter dopamine, which is important in mediating drug reward such as nicotine in tobacco smoke. Different COMT alleles encode enzyme whose activity varies from three- to fourfold that may affect dopamine levels and alter subjective effects of nicotine. Recent evidence also suggests that a COMT polymorphism may be especially important in determining an individual's predisposition to developing nicotine dependence.
  
  
  METHODS
  We studied the COMT Val108Met polymorphism in a male population of 203 current smokers, 66 former smokers, and 102 non-smokers. The age-adjusted odds ratios were estimated by multiple logistic regression models.
  
  
  RESULTS
  The results showed no significant association of the COMT Val108Met with initiation, persistent smoking, or smoking cessation. However, current smokers with the Met allele had significantly higher Fagerstrom Test for Nicotine Dependence scores (7.5 +/- 2.1 vs 6.8 +/- 1.8, p = 0.018) and started smoking significantly earlier (18.4 +/- 4.9 vs 20.1 +/- 5.9 years, p = 0.036).
  
  
  CONCLUSIONS
  These results suggest that the COMT Val108Met polymorphism may not influence smoking status in a Chinese male population but may influence the age at which smoking started and smoking severity among smokers. However, the findings must be regarded as preliminary because of the relatively small sample size and marginal associations and should be replicated in a larger cohort.
authors.affiliation: Institute of Mental Health, Peking University, Beijing, 100083, China.
authors.forename: Song
authors.initials: S
authors.lastname: Guo
authors.forename: Da Fang
authors.initials: DF
authors.lastname: Chen
authors.forename: Dong Feng
authors.initials: DF
authors.lastname: Zhou
authors.forename: Hong Qiang
authors.initials: HQ
authors.lastname: Sun
authors.forename: Gui Ying
authors.initials: GY
authors.lastname: Wu
authors.forename: Colin N
authors.initials: CN
authors.lastname: Haile
authors.forename: Therese A
authors.initials: TA
authors.lastname: Kosten
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Kosten
authors.forename: Xiang Yang
authors.initials: XY
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D044466:Asian People / Q000235:genetics*; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D002681:China; D015331:Cohort Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008297:Male; D008715:Methionine; D008875:Middle Aged; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D012907:Smoking / Q000235:genetics* / Q000378:metabolism; D016540:Smoking Cessation; D014029:Tobacco Use Disorder / Q000201:enzymology / Q000235:genetics*; D014633:Valine
chemical_list: D008715:Methionine; D002394:Catechol O-Methyltransferase; D014633:Valine