In the apical junction gene set, potassium voltage-gated channel subfamily B member 2 (KCNB2), collagen type VI alpha-1 chain (COL6A1), and transforming growth factor-beta 3 (TGFB3) showed higher levels in pre-symptomatic individuals (p < 0.001) compared with all other proteins that were of higher levels in RA patients (p < 0.001–0.01) (Additional file 4: Figure S2). Here, COL6A1 is linked to rheumatoid arthritis.