The relationship of PADI4_94 polymorphisms with the morbidity of rheumatoid arthritis in Caucasian and Asian populations: a meta-analysis and system review

Rheumatoid arthritis (RA) is a systemic autoimmune disease that is characterized by chronic, destructive, and debilitating arthritis. Peptidyl arginine deiminase type 4 (PADI4) polymorphisms (PADI4_94) have been reported to play a vital role in the disease. Nevertheless, the results were inconclusive. An electronic search of Embase, PubMed, CNKI, and WANFANG Date was performed to the identification of relevant studies published from 2003 to 2017. A total of 20 studies were enrolled as being eligible for analysis. In overall analysis, we had found a significant correlation between the PADI4_94 polymorphisms and RA under T vs. C (OR = 1.05, 95% CI 1.01–1.08, P = 0.01). Nevertheless, there were no significant associations under other four genetic models. In the subgroup analysis, we had observed the similar results in Asian population (T vs. C: OR = 1.11, 95% CI 1.05–1.17, P = 0.001), whereas no significant difference were observed in Caucasian population under any genetic model (P > 0.05). In conclusion, our meta-analysis demonstrated that the PADI4_94 polymorphisms might contribute to RA susceptibility especially in Asian populations but not in Caucasian populations. More well-designed studies with larger sample size are still required to further elucidate the relationship.