IKBKB and rectal cancer: We were able to identify genotype combinations that appear to influence risk of colon and rectal cancer using hapConstructor for SNPs across IKBKB, IL6, and NFKB1. In colon cancer, a two-SNP composite genotype comprised of IL6 rs1800797 (dominant model) and NFKB1 rs4648110 (recessive model) was significantly associated with 60% decreased risk (P = 0.0004; FDR q = 0.037).