Since our original study of CSNK1E in humans we have replicated the association between rs135745 and the subjectively euphoric effects of amphetamine with almost 300 new human subjects. To our knowledge, the effect of the SNPs rs1534891-rs6001093-rs135757 on heroin addiction has not been replicated in any independent samples; how ever, an association between bipolar disorder and a collection of three unlinked SNPs including rs1534891 has been reported (Shi et al. 2008), providing modest evidence that rs1534891 could have some biologically meaningful effect.
