and nicotine co-dependence, not for any other non-alcoholism neuropsychiatric disorder examined. This region has been suggestively associated with alcohol dependence (75.6% nicotine dependence) in the same dataset before (p=2.3×10−6 by Bierut et al. 2010; p=2.8×10−7 by Zuo et al. 2011), but not genome-wide significant (α=5×10−8). The association was genome-wide significant only in the subgroup with alcohol and nicotine co-dependence (p=6.2×10−9), which might suggest that this region is associated with a more severe subtype of alcohol dependence.
