Eight thousand, nine hundred and fourty-eight SNPs and indels (average of 1 marker per 62 base pairs) were selected for the 552 kb LD block encompasing the chr15q25.1 nicotinic acetylcholine receptor (nAChR) gene cluster (CHRNA5, CHRNA3 and CHRNB4). For CYP2A6 (±20 kb), 612 markers were selected with an average of 1 marker every 75 base pairs. For CYP2B6 (±20 kb), 1628 markers were selected with 1 marker per 45 base pairs on average. As expected, the imputed coverage and average obsRSQ was greater than 99 % in the 1000 Genomes Project Phase 1 YRI, ASN, and EUR populations, regardless of minor allele frequency. Additional markers were selected to capture variation in the surrounding region, including EGLN2, CYP2A7, CYP2G1P, and CYP2B7P1.
