Whether this chromosome 15 region plays a role in smoking cessation is less clear. Two genetic studies of smoking cessation found no evidence that variants in this region influence successful quitting [33-34]. However, two other studies have demonstrated the role of this locus in smoking cessation [21, 35]. In addition, a recent study of pregnant smokers showed that this chromosome 15 variant predicted who continued smoking during pregnancy [36]. Though the genetic association with nicotine dependence and smoking quantity is very robust, this region appears to play a smaller role in cessation.
