NATD1 and Arthritis: Three of these were upregulated in DA.F344(Cia5d) FLS (Ncor1, Trim41, and Gtlf3b) and two were downregulated in DA.F344(Cia5d) (Trpv2 and Trim16), raising the possibility that a polymorphism/mutation in one of these genes could explain the arthritis and FLS invasive phenotypes attributed to Cia5d. Specifically, a polymorphism in a regulatory element or intron in one of these genes, or in another gene in the region, could influence transcription, thus explaining differences in levels of mRNA and disease.