These results are consistent with those from previous GWA studies on Eysenck’s Neuroticism scale (Shifman, et al., 2008) and the Big Five personality traits (Terracciano, et al., 2008), and prior genome-wide linkage studies on personality scales, which have failed to identify any consistently replicable genome-wide significant variants. However, the (lack of) results in genome-wide searches contrast with some earlier candidate gene studies that found association of DRD4 and SLC6A4 with Novelty Seeking/Extraversion and Harm Avoidance/Neuroticism, respectively (e.g., Benjamin, et al., 1996; Ebstein, 2006; Vormfelde, et al., 2006). Tellingly, these two genes showed no association at all with the corresponding scales in the present study despite the very large sample size, consistent with more recent evidence against a link between these genes and personality (Munafo, et al., 2009; Terracciano, et al., 2009).
