THE AUTOIMMUNE PTPN22 VARIANT RS2476601 IS ASSOCIATED WITH RHEUMATOID ARTHRITIS RISK BUT NOT WITH SYSTEMIC BONE LOSS.

Introduction: PTPN22 is a powerful inhibitor of signaling cascades initiated in various immune cells. The association between the PTPN22 variant rs2476601 and rheumatoid arthritis (RA) varies by ethnicity. PTPN22 rs2476601 exhibits the strongest non-HLA association with RA in Caucasians. However, data in the Tunisian population are inconsistent. Among patients with RA, PTPN22 rs2476601 has been shown to be associated with bone erosion and autoantibodies. However, no association with systemic bone loss (SBL) has been investigated so far. The aim of this study was to assessthe association of PTPN22 rs2476601 with RA risk and SBL. Methods:In this case-control cross-sectional study, PTPN22 rs2476601 was genotyped by PCR- Restriction Fragment Length Polymorphism in 363 Tunisian patients with RA and 217 controls. Bone mineral density was assessed by dual-energy X-ray absorptiometry in 216 RA patients.