Association between monoamine oxidase gene polymorphisms and smoking behaviour in Chinese males

Abstract

Monoamine oxidase (MAO) is a critical metabolic enzyme of dopamine, which is a key neurotransmitter of the mesolimbic reward pathway in the human brain. Consequently, the gene encoding MAO is an important candidate gene in the genetics of smoking behaviour. We investigated the association between MAOA polymorphisms (a VNTR polymorphism and an EcoRV polymorphism) and smoking status. A community-based cross-sectional study was conducted with 203 current smoking subjects and 168 non-current smoking subjects in Beijing, China. Genotyping for these polymorphisms was performed using PCR and restriction fragment length polymorphism. Multiple logistic regression models were used to analyse the association of MAOA gene polymorphisms with smoking status. We found that individuals with the 1460T/O genotype had a significantly increased the risk of smoking compared to those with 1460C/O. The adjusted odds ratios (aORs) were 3.2 (95% CI 2.0-5.2) in current vs. non-current smokers group, 1.7 (95% CI 1.1-2.8) in ever vs. never smokers group, 2.5 (95% CI 1.4-4.3) in current vs. never smokers group, and 5.3 (95% CI 2.5-11.2) in current vs. former smokers group respectively. We also found that individuals with the 3-repeat genotype of the VNTR polymorphism had a significantly increased risk of smoking significantly compared to those with the 4-repeat genotype. The aORs were 2.0 (95% CI 1.0-4.1) in the current vs. former smokers group, and 1.9 (95% CI 1.0-3.6) in the nicotine dependent vs. non-nicotine dependent group respectively. Moreover, MAOA gene haplotypes were associated significantly with nicotine dependence in every group. In conclusion, there is an important association between MAOA polymorphisms and smoking status, suggesting a possible role of MAOA gene variants in nicotine dependence.

Overview of the pharmacogenomics of cigarette smoking

“…106 Another study of Chinese males found those with both the four-repeat allele and 1460C allele were least likely to be current smokers. 107 In adolescents, no associations of the MAO-A VNTR polymorphisms or 1460C4T SNP were found between current, former or never smokers. 82 Catechol-O-methyltransferase is important in the degradation catecholamines, and a functional SNP (1947G4A) corresponding to Val108/158Met has been identified.…”

O papel do polimorfismo funcional VNTR da região promotora do gene MAOA nos transtornos psiquiátricos

“…Ito et al 86 and Jin et al 87 reported that individuals with the 3-repeat allele had a greater risk of smoking, when compared to those with the 4-repeat allele in Asian populations. In contrast, Wiesbeck et al 88 reported an association between the 4-repeat allele and a greater quantity of daily cigarettes in Caucasian men with both alcohol and tobacco dependence.…”

Constitutional mechanisms of vulnerability and resilience to nicotine dependence

“…Some studies have shown a positive association between the high-activity alleles and an increased risk of nicotine dependence, 155–157 but other studies have failed to confirm this association. 158,159 These studies have many procedural differences, including the gender, age and other characteristics of the sample population and the definition of dependence, which make direct comparisons difficult.…”