Seeking (Benjamin, et al., 1996; Ebstein, Nemanov, Klotz, Gritsenko, & Belmaker, 1997; Ebstein, et al., 1996), and between a polymorphism (5-HTTLPR) in the promoter region of the serotonin transporter gene and anxiety-related traits like Harm Avoidance (Lesch, et al., 1996; Vormfelde, et al., 2006). However, other studies were unsuccessful in replicating these associations (i.e., Becker, El-Faddagh, Schmidt, & Laucht, 2007; Ebstein, Gritsenko, et al., 1997; Herbst, et al., 2000; Lang, et al., 2004; Malhotra, et al., 1996). A recent meta-analysis (Munafo, Yalcin, Willis-Owen, & Flint, 2008) concluded that the DRD4 gene (C-521T polymorphism) may be associated with Novelty Seeking and Impulsivity, explaining up to 3% of the phenotypic variance, but that publication bias may have distorted the findings. Another meta-analysis (Munafo, et al., 2009) found no significant association of the 5-HTTLPR genotype with Harm Avoidance or Eysenck’s Neuroticism scale, but they did report a significant association with the NEO Neuroticism scale. Two more recent large studies provided further mixed evidence, with one reporting no association of 5-HTTLPR with Neuroticism (Terracciano, et al., 2009), and the other finding a significant association with Neuroticism but not Harm Avoidance (Wray, et al., 2009).
