PTPN22, CTLA4, FcγRIIa, FcγRIIIa and FcγRIIIb polymorphisms in Tunisian patients with systemic lupus erythematosus

Background: Pathogenesis of systemic lupus erythematosus (SLE) involves both T cell tolerance breakdown and pathogenic autoantibodies. Polymorphisms in T cell regulatory proteins (PTPN22 and CTLA-4) and IgG receptors (FcγR) genes could impact their functions. Consequently, we aimed to study the role of PTPN22, CTLA-4, FcγRII and FcγRIII polymorphisms on either SLE susceptibility or its severity. Methods: Consequently, PTPN22 rs2476601 (R620W), CTLA-4 rs231775 (+49 A/G), FcγRIIa rs1801274 (R131H), FcγRIIIa rs396991 (F158V) and FcγRIIIb Na1/Na2 polymorphisms were examined in 137 SLE patients and 100 healthy blood donors matched in age, gender and ethnic origin. Results: The PTPN22-620*W mutant allele was significantly more prevalent in SLE patients comparatively to controls; p=0.001, OR [95% CI] = 7.8 [1.73-48.85]. Inversely, the frequency of the CTLA-4*G/G homozygous genotype was significantly lower in patients (35%) than in controls; p=0.02, OR [95% CI] = 0.54 [0.31-0.94]. Regarding to FcγR polymorphisms, while the FcγRIIIa*V allele was more prevalent in case of SLE (0.562 vs 0.35); p=0.001, OR [95% CI] = 2.77 [1.38-5.68], FcγRIIa and FcγRIIIb did not show any association with SLE. Analytic results showed that the prevalence of anti-dsDNA autoantibody was significantly higher in patients carrying PTPN22*W allele p=0.038. Otherwise, no correlation was found between the five studied polymorphisms and either clinical or biological patients characteristics. Conclusion: PTPN22 R620W, CTLA-A +49 A/G and FcγRIIIa F158V polymorphisms seem to be related to SLE susceptibility in Tunisian.