Csnk1e was identified because it was differentially expressed in mice divergently selected for high and low locomotor response to methamphetamine. Moreover, there was a robust expression QTL that co-mapped to a QTL for the locomotor response to methamphetamine (Palmer et al. 2005). Finally, Csnk1e modulates the activity of dopamine and adenosine 3′:5′-monophosphate-regulated phospho-protein of 32 kDa (Darpp-32) which is a critical second messenger pathway that mediates the response to various drugs of abuse (Walaas et al. 2011). The locomotor response to a drug is sometimes equated with the subjectively rewarding effects of a drug in humans (Wise and Bozarth 1987) although this is controversial (Phillips et al. 2008). Inspired by this idea, we made an effort to translate this finding to humans. We examined the association between polymorphisms in CSNK1E and the subjectively rewarding effects of stimulant drugs in human volunteers (N = 96) who had received placebo or d-amphetamine (10, 20 mg) in a double-blind, within-subjects laboratory-based study. A SNP in CSNK1E (rs135745) was associated with the subjectively euphoric effects of amphetamine (Veenstra-VanderWeele et al. 2006), providing some support
