Two chemokine gene SNPs—C-C motif chemokine receptor 3 (CCR3) and C-C motif chemokine receptor 2 (CCR2)—may be involved due to the attraction of leucocytes in inflammatory joint loci both in OA and RA, and together with SNPs of the IL4 gene and its receptor, as discussed above, a SNP of TYK2-coding protein associated with the cytoplasmic domain of type I and type II cytokine receptors, and being a part of IFN type I and type III signaling pathways (NCBI), demonstrates the involvement of the immune system not only in RA but in OA as well. The gene discussed is CCR2; the disease is rheumatoid arthritis.