Human genetic variability in DAT, the gene encoding DAT (SLC6A3, GeneID 6531; National Center for Biotechnology Information 2009) has been associated with disorders and behaviors thought to be influenced by dopamine signaling such as attention-deficit hyperactivity disorder (Yang et al. 2007), bipolar disorders (Greenwood et al. 2006), and smoking cessation (Stapleton et al. 2007). Here, SLC6A3 is linked to bipolar disorder.