When using plasma proteins from Iceland, eight proteins (AGER, TNFAIP3, ICOSLG, CILP2, HAPLN4, BMP1, EHBP1, and USP8) exhibited high colocalization support (PH4 ≥ 0.8) and six proteins (F2, TEC, FCRL1, PPA2, PMEL and JUND) exhibited medium colocalization support (PH4 = 0.5 - 0.8) for RA. This evidence concerns the gene ICOSLG and rheumatoid arthritis.