One SNP in the promoter region of NPY2R (rs6857715) and two SNPs further upstream of the gene (rs4333136 and rs4425326) were associated with alcohol dependence (p<0.03), and two of these with the secondary phenotype of severe withdrawal (Table 2). Five SNPs in this gene, the same three plus rs2342675 and rs17304901, were associated with cocaine dependence (Table 2). The same three SNPs were also associated with comorbid alcohol and cocaine dependence (rs687715, p=0.006; rs4333136, p=0.02; rs4425326, p=0.03; all other SNPs were non-significant (p>0.07), data not shown). To determine whether the significant evidence of association for alcohol dependence was due to the subset of affected individuals who also met criteria for cocaine dependence (208 of the 753; Table 1), the analysis was repeated using only alcohol dependent individuals who were not cocaine dependent; there was no significant association of alcohol-only dependence with any of the SNPs (p>0.08, data not shown).
