Finally, we examined evidence for association in our sample for candidate genes and SNPs published in earlier association studies of personality, including the serotonin receptor gene (SLC6A4), the dopamine D4 receptor gene (DRD4), and SNPs and genes reported in previous GWA studies on personality (Shifman, et al., 2008; Terracciano, et al., 2008; van den Oord, et al., 2008). There have been no previous GWA studies on Cloninger’s scales, but there is substantial overlap between Cloninger’s scales and the Big Five/Eysenck’s scales. Based on inter-scale correlations reported in de Fruyt et al. (2000), we looked for overlapping signals in the following groups: Neuroticism (Harm Avoidance), Extraversion and Openness (Harm Avoidance, Novelty Seeking, and Reward Dependence), and Conscientiousness (Harm Avoidance, Novelty Seeking, and Persistence).
