NFKB1 and rheumatoid arthritis: The HaploReg database predicted that the two synonymous variations that reference the C-alleles of Exon 5 rs878081 and Exon 6 rs1055311 have lower affinities of binding to the DNA-binding motif of the NF-κB family, although rs1055311 was not associated with an RA risk but with a high level of aCCP and disease activity.