Linkage disequilibrium patterns were discerned using LocusZoom (56) and Haploview (57) with reference to two 1000 Genomes panels: EUR (comprised of European Americans, Finns, Britons, Spaniards, and Italians) and AFR (comprised of African Americans, Kenyans, and Nigerians). SNPs were annotated according to their location in the longest principal isoform for OPRM1, according to the APPRIS database (58). Regulatory SNP annotations were taken from the HaploReg database containing information on chromatin states, conservation, and regulatory motif alterations from the Encyclopedia of DNA Elements and elsewhere (59).
