In summary, genetic studies of nicotine dependence have successfully identified risk factors using both GWAS and candidate gene approaches. The consistent phenotypic measure---CPD---is easily obtained in large cohort studies and has been successfully used in meta-analyses of the genetics of smoking. These studies have greatly increased the power to detect genetic risk factors for nicotine consumption. However, these associated genetic factors explain only a small percentage of the variance in nicotine consumption, indicating that further research to detect other genetic factors influencing smoking is warranted.
