PCA analysis displayed that in both IAR and RA+ patients, serum markers clustered in 3 areas, with Leptin being present in Cluster 1 in both cohorts For Cluster 3, SAA, sICAM-1, c-Peptide, sVCAM-1 and MMP1 clustered together in both IAR and RA+ (Fig. 5C), thus suggesting that the measurements of these markers together might aid in identifying individuals at risk who may convert to RA+. This evidence concerns the gene MMP1 and rheumatoid arthritis.