In order to account for multiple comparisons, the significance threshold for pharmacogenetic effects was divided by the number of independent comparisons. Specifically, linkage disequilibrium (LD) across the tSNPs sampled in the OPRK1 and OPRD1 genes were used to determine dependence (i.e., overlap) between the tSNPs of interest. Thus, accounting for one haplotype block for the OPRD1 tSNPs and one for the OPRK1 tSNPs (see Figure 1), a total of 5 independent comparisons were conducted. Therefore, the critical p-value (p = .05) was divided by 5 resulting in a corrected critical p-value of p = 0.01 for the pharmacogenetic hypotheses. Lastly, given that the genes coding for mu, kappa, and delta receptors are located on different chromosomes (chromosomes 6, 8, and 1, respectively), there was no concern about LD across the three genes.
