including variation in 1) alcohol-specific physiological measures like initial sensitivity and tolerance (Schuckit et al., 1997), 2) brain reward circuitry implicated in substance use and other pathological behaviors (Volkow et al., 2012),, and 3) personality traits like internalizing and externalizing behaviors (Harford et al., 2013), which are unlikely to be influenced by the same genes. As in other complex traits, these issues will be overcome primarily by increasing sample size and power. Finally, since both KLF12 and RYR3 were previously implicated in substance phenotypes, our findings may be considered as replication evidence for these signals.
