same region being also reported by Uhl et al. to be associated with illicit drug abuse (Uhl et al. 2002). Regions on chromosome 18 were suggested to harbor GVs potentially associated with initiation of cannabis use (Agrawal et al. 2008a), methamphetamine abuse (Lee et al. 2014) and alcohol dependence (Prescott et al. 2006). However, when tested individually, none of the GVs achieved an association P-value less than the adapted (i.e., for multiple testing) alpha of 1 × 10−8.
