!Name=Genes and Immunity 2003 !ExptSetNo=1874 !Description=Rheumatoid arthritis (RA) is a heterogeneous disease. We used cDNA microarray technology to subclassify RA patients and disclose disease pathways in rheumatoid synovium. Hierarchical clustering of gene expression data identified two main groups of tissues (RA-I and RA-II). A total of 121 genes were significantly higher expressed in the RA-I tissues, whereas 39 genes were overexpressed in the RA-II tissues. Among the 121 genes overexpressed in RA-I tissues, a relative majority of nine genes are located on chromosome 6p21.3. An interpretation of biological processes that take place revealed that the gene expression profile in RA-I tissues is indicative for an adaptive immune response. The RA-II group showed expression of genes suggestive for fibroblast dedifferentiation. Within the RA-I group, two subgroups could be distinguished; the RA-Ia group showed predominantly immune-related gene activity, while the RA-Ib group showed an additional higher activity of genes indicative for the classical pathway of complement activation. All tissues except the RA-Ia subgroup showed elevated expression of genes involved in tissue remodeling. These results confirm the heterogeneous nature of RA and suggest the existence of distinct pathogenic mechanisms that contribute to RA. The differences in expression profiles provide opportunities to stratify patients based on molecular criteria. !Name=RA LB-12 shai016 vs CRE syn tiss !Exptid=10447 !Name=RA LB-25 shr125 vs CRE syn tis !Exptid=10517 !Name=RA LUMC-04 sht077 vs CRC syn tis !Exptid=11632 !Name=RA LUMC-12 shr128 vs CRE syn tis !Exptid=10444 !Name=RA LUMC-19 shab097 vs CRD syn tis !Exptid=11677 !Name=RA LUMC-21 shai014 vs CRE syn tiss !Exptid=10445 !Name=RA LUMC-27 shab088a vs CRD syn tis !Exptid=10514 !Name=RA LUMC-30 shab102tgp vs CRD syn tis !Exptid=4197 !Name=RA LUMC-42 shab111 vs CRD syn tis !Exptid=11679 !Name=RA LUMC-48 shab108 vs CRD syn tis !Exptid=10371 !Name=RA LUMC-48 sht076a vs CRC syn tis !Exptid=11622 !Name=RA LUMC-5 shab100 vs CRD !Exptid=10553 !Name=RA LUMC-53 shab101 vs CRD !Exptid=10554 !Name=RA LUMC-57 shab094 vs CRD syn tis !Exptid=11675 !Name=RA LUMC-7 shab110 vs CRD syn tis !Exptid=10373 !Name=RA LUMC-8 shai013a vs CRE syn tis !Exptid=10518