Previous studies have explored the relationship of PTPN22 and TLR9 polymorphisms with systemic lupus erythematosus (SLE). In consideration of the population stratification, conflicting results and updating data, we conducted a comprehensive meta-analysis, which consists of a total of 17 research articles (9120 cases and 11,724 controls) for PTPN22 and 20 articles (including up to 2808 cases and 3386 controls) for TLR9. Significant association was verified between PTPN22 rs2476601 and SLE in the overall population (OR = 1.511 per T allele, 95% CI 1.338-1.706, P = 2.931 × 10) and under dominant model of T allele (TT+CT vs. CC: OR = 1.531, 95% CI 1.346-1.742, P = 9.17 × 10). Analysis after stratification by ethnicity indicated that PTPN22 rs2476601 was related to SLE in Americans (OR = 2.566, 95% CI 1.796-3.665, P = 2.219 × 10), Europeans (OR = 1.399, 95% CI 1.261-1.552, P = 2.153 × 10), and Africans (OR = 4.14, 95% CI 1.753-9.775, P = 1.0 × 10). We did not observe any association between TLR9 polymorphisms (rs187084, rs352140, rs5743836 and rs352139) and SLE under any model, after excluding the data that were inconsistent with Hardy-Weinberg equilibrium (HWE). In summary, PTPN22 rs2476601 was significantly interrelated with SLE and contributed to susceptibility and development of SLE in Americans, Europeans and Africans in this analysis, while their relationship needs to be validated in Africans by future research.

Previous studies have reported that genes relating to JAK-STAT pathway (IFIH1, TYK2 and IL-10) conferred the susceptibility to SLE. In this study, we performed a meta-analysis (including 43 studies) to evaluate the association between IFIH1 (9288 patients and 24,040 controls), TYK2 (4928 patients and 11,536 controls), IL-10 (3623 patients and 4907 controls) polymorphisms and systemic lupus erythematosus (SLE) in a comprehensive way. We found that IFIH1 rs1990760_T allele was associated with risk of SLE in overall population under three models (allelic: P = 2.56 × 10, OR 1.135, 95% CI 1.094-1.179, dominant: P = 1.8 × 10, OR 1.203, 95% CI 1.128-1.284, recessive: P = 2.6 × 10, OR 1.163, 95% CI 1.098-1.231). A strong association had been observed between TYK2 polymorphism rs2304256_C allele and SLE in Europeans (P = 5.82 × 10, OR 1.434, 95% CI 1.203-1.710). When coming to overall population, TYK2 rs2304256_C showed a significant association with SLE under recessive model (P = 8.05 × 10, OR 1.314, 95% CI 1.074-1.608). However, the other two SNPs (rs12720270, rs280519) of TYK2 were not significant. The results also indicated an association between IL-10 rs1800896_G allele and SLE in Asians under recessive model (P = 4.65 × 10, OR 2.623, 95% CI 1.346-5.115), while, IL-10 rs1800896_G had a trend of association with SLE in European population in dominant model (P = 1.21 × 10, OR 1.375, 95% CI 1.072-1.764). In addition, we found IL-10 rs1800896 GG homozygote might be associated with increased susceptibility to SLE (GG vs AA, P = 4.65 × 10, OR 1.539, 95% CI 1.142-2.072). We concluded that IFIH1 rs1990760_T and TYK2 rs2304256_C alleles were significantly associated with SLE, and IL-10 rs1800896 GG homozygote might have an enhancement effect on SLE risk.