HYKK and lung carcinoma: We defined the eight significant SNPs, which were rs1051730 in CHRNA3; rs1996371, rs6495314, rs11638372, rs4887077, and rs6495309 in CHRNB4; and rs8034191 and rs2036534 in HYKK, as the index SNPs for lung cancer risk, and used these eight SNPs to further select the candidate SNPs, which interacted with the eight index SNPs.