Rs3778150 and the top prior SNP rs3823010 were in perfect linkage disequilibrium (r2=1 and D’=1) with equivalent minor allele frequencies at 15% in EUR, and although D’=1 in AFR, their moderate r2 value of 0.54 reflected varied minor allele frequencies (20% for rs3778150 and 12% for rs3823010). In the African American cohorts from the current study where the SNPs were not collinear, both SNPs were associated with heroin addiction (African American-specific meta-analysis P=0.013 for rs3778150 and 0.0087 for rs3823010), but in follow-up regression analyses with both rs3778150 and rs3823010 included as predictors, neither SNP association remained (African American-specific meta-analysis P=0.48 for rs3778150 and 0.38 for rs3823010), suggesting that their associations with heroin addiction reflect the same underlying signal.
