After applying the stringent Bonferroni correction for multiple testing (p<0.0045 [0.05/11] for the 11 tests), only the effect of the DRD2 TaqIB SNP remained significant (labeled by an asterisk in Table 1) suggesting that the presence of the DRD2 TaqIB minor allele is a strongly relevant component in the genetic background of heroin dependence. This evidence concerns the gene DRD2 and heroin dependence.