Genome-wide association studies (GWASs) of nicotine use behaviors have largely focused on phenotypes that are easily ascertained through self-report questionnaires (e.g. When did you start smoking?, Are you a current smoker?, and How many cigarettes do you smoke in a day?). The largest GWASs of tobacco smoking behaviors to date identified 140 loci associated with CPD (N = 784,353) and 1,346 loci related to the initiation of regular smoking (SmkInit; N ~ 3.38 million) (Saunders et al., 2022).
