We also demonstrated that the significant ND-associated variants (rs1948, rs7178270, and rs3743075) are novel cis-meQTLs influencing both the extent of methylation and mRNA expression of CHRNA3. In addition, through SNP-by-SNP interaction study, we found several SNPs in CHRNA5/B4, CHRNA5/A4/B2, and CHRNA7 that interactively confer susceptibility to ND in our Han sample. This evidence concerns the gene CHRNA7 and Norrie disease.