Although replications have been reported (Ebstein et al 1997; Ono et al 1997; Noble et al 1998; Ricketts et al 1998; Katsugari et al 1999; Strobel et al 1999; Keltikangas-Jarvinen et al 2003), there also have been numerous failures to replicate the associations with DRD4 (Malhotra et al 1996; Gelernter et al 1997; Sander et al 1997; Pogue-Geile et al 1998; Sullivan et al 1998; Ekelund et al 1999; Kühn et al 1999) and 5-HTTLPR (Ebstein et al 1997; Gelernter et al 1998; Mazzanti et al 1998; Kumakiri et al 1999). Other studies also failed to replicate any positive involvement in both neurotransmitters, ie, between the DRD4 polymorphism and novelty seeking, and between the 5-HTTLPR polymorphism and harm avoidance (Ball et al 1999; Herbst et al 2000). Such failures to replicate raise the question of whether the temperament-character model adequately taps the genetic architecture of personality.
