GPNMB and rheumatoid arthritis: Since LBP lessened the RA, we focused on those down-regulated genes caused by DNA hypermethylation and eventually screened out 10 genes including Dpep3, Gstm6, Slc27a2, Col11a2, Sycp2, SNORA22, Tnni1, Gpnmb, Mypn and Acsl6, which can be divided into 3 categories.