In a study by Bond et al. [73], the investigators concluded that the most prevalent SNPs in the OPRM1 gene occurred at A118G (rs1799971) and C17T (rs1799972); other SNPs were located at A24G, G779A, and G942A [73]. There were significant differences between the observed allelic frequencies of African-American, Caucasian, and Hispanic ethnic groups for both rs1799971 and rs1799972 alleles (χ2=7.15 (P=0.028) and χ 2=26.0 (p<0.0001) respectively) [73]. Bond’s study found no significant differences in rs1799971 allelic frequency between opioid-dependent and non-dependent subjects with all ethnic groups combined [χ2=1.81 (P=0.159)], however in subgroup analyses by ethnicity, the rs1799971 minor allele (G) frequency was significantly higher in non-opioid dependent Hispanic subjects (χ2 = 8.22, d.f. = 1, P = 0.0041) [73]. On the other hand, the rs1799972 minor allele (T) frequency was higher in subjects with opioid dependence (χ2 = 3.70, d.f. = 1, P = 0.054) [73]. Different patterns are observed in a group of American, Finish, and Native American subjects where the minor allele frequency of the rs1799971 SNP was 10.5-16.3% without any significant detection of the rs1799972 polymorphism [73].
