These findings suggest that MAOArs1137070 contributes to the susceptibility to nicotine dependence through its influence on brain circuits involved in reward and attention, and interacts with smoking in the progression.
Among smokers with DRD2 rs1079597 GG//MAOArs309850 3-repeat, the OR of heavier smoking was 2.67 times higher (95% confidence interval [CI]: [1.08, 6.59], p = .031) and the score on the Fagerstrom test for nicotine dependence was higher (4.26 vs. 2.83) than in those with DRD2 rs1079597 AA//MAOArs309850 3-repeat.
Prior work using lymphoblast DNA prepared from 192 subjects from the Iowa Adoption Studies (IAS) demonstrated that decreased MAOA promoter methylation was associated with lifetime symptom count for nicotine dependence (ND) and provided suggestive evidence that the amount of methylation is genotype dependent.
In conclusion, there is an important association between MAOA polymorphisms and smoking status, suggesting a possible role of MAOA gene variants in nicotine dependence.