Both the range encompassing the entirety of CYP2A6 and CYP2B6 genes (±20 kb) and the range defined by the largest linkage disequilibrium (LD) block encompassing the nAChR gene cluster were defined. All known variants were selected from multiple databases, including 1000 Genomes Project Phase 1, HapMap, and the NHLBI GO Exome Sequencing Project [89].
