title: Association between monoamine oxidase gene polymorphisms and smoking behavior: A meta-analysis.
abstract: BACKGROUND
  A number of studies have researched the association between monoamine oxidase gene (MAO) polymorphisms and smoking behavior, but the conclusion is quite inconsistent. A meta-analysis was conducted to assess the association of MAO-A C1460T, MAO-A VNTR and MAO-B G644A polymorphisms with smoking behavior.
  
  
  METHODS
  A comprehensive search was performed to identify all eligible studies. Meta-analysis was applied to calculate the pooled effect values and their 95% confidence intervals. Meta-regression and the 'leave one out' sensitivity analysis were used to explore potential sources of heterogeneity. The risk of bias was assessed by the Egger regression asymmetry test.
  
  
  RESULTS
  11 articles conformed to the inclusion criteria. The meta-analysis showed T allele in MAO-A C1460T reduced the risk of heavy smoking (OR=0.66, 95% CI: 0.52-0.84; I(2)=0.0%), especially in Caucasians; the active group in MAO-A VNTR increased the likelihood of failed smoking cessation in males (OR=1.49, 95% CI: 1.01-2.22; I(2)=0.0%); A allele in MAO-B G644A reduced the risk of heavy smoking in males (OR=0.20, 95% CI: 0.04-0.98).
  
  
  CONCLUSIONS
  Our findings indicate that the low activity of monoamine oxidase gene polymorphisms has a protective effect on smoking cessation and heaviness. Some associations and applications should be further confirmed.
authors.affiliation: Department of Epidemiology and Biostatistics, Shandong University, Jinan 250012, Shandong, PR China.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Epidemiology and Biostatistics, Shandong University, Jinan 250012, Shandong, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Department of Epidemiology and Biostatistics, Shandong University, Jinan 250012, Shandong, PR China.
authors.forename: Suyun
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Epidemiology and Biostatistics, Shandong University, Jinan 250012, Shandong, PR China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Epidemiology and Biostatistics, Shandong University, Jinan 250012, Shandong, PR China.
authors.forename: Lulu
authors.initials: L
authors.lastname: Pan
authors.affiliation: Department of Epidemiology and Biostatistics, Shandong University, Jinan 250012, Shandong, PR China. Electronic address: jiachongqi@sdu.edu.cn.
authors.forename: Chongqi
authors.initials: C
authors.lastname: Jia
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008995:Monoamine Oxidase / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics; D012907:Smoking / Q000235:genetics* / Q000523:psychology*; D016540:Smoking Cessation; D055815:Young Adult
chemical_list: D008995:Monoamine Oxidase
keywords: MAO-A; MAO-B; Meta-analysis; Monoamine oxidase gene; Polymorphism; Smoking behavior