difference in the genotypic distribution was found between the absent and present subgroups of polydrug use among the patients with METH dependence (χ2=3.979, P=0.046). Indeed, fewer polydrug abusers carried the C/C genotype compared with monodrug users (Table 1). A similar result was found in the patients with alcohol dependence. A significant difference in the genotypic distribution was found between the absent and present subgroups of drug use among patients with alcohol dependence (χ2=3.860, P=0.049, and χ2=3.039, P=0.097, in the additive and recessive models, respectively), and a lower proportion of drug abusers carried the C allele or C/C genotype compared with the alcoholics without drug abuse (Table 1). Furthermore, a significant difference in allelic distribution was found between the absent and present subgroups of comorbid dependence among the patients with eating disorders (χ2=3.985, P=0.046, and χ2=4.488, P=0.034, in the additive and dominant models, respectively), and a lower proportion of patients with drug dependence carried the C allele compared with the patients without drug dependence (Table 1). Although nonsignificant, likely because of the small sample size, a marginal difference was observed in allelic distribution between the absent (χ2=3.780, P=0.052) and present subgroups with a comorbid alcoholic state among the patients with eating
