Taking all these considerations into account, in this study we determined if the most relevant PTPN22 (rs2488457, rs2476601 and rs33996649) and CSK (rs34933034 and rs1378942) polymorphisms may influence on PTPN22 and CSK expression in whole peripheral blood of RA patients when compared to healthy controls. The gene discussed is CSK; the disease is rheumatoid arthritis.