Among all markers, SNP2 (rs1042363) at exon 9 or SNP6 (rs1800759) at the promoter showed the greatest degree of HWD, among patients with either alcohol dependence or drug dependence.
Logistic regression analysis showed that: (i) the genotypes of SNP2 (rs1042363) were significantly associated with alcohol dependence and drug dependence (mainly cocaine dependence), and the genotypes of SNP3 (rs1126671) were also significantly associated with alcohol dependence and (ii) one seven-variant haplotype and one diplotype were significantly associated with alcohol dependence and other seven-variant diplotypes were significantly associated with drug dependence (including cocaine and opioid dependence).