PRTN3 and rheumatoid arthritis: As shown in Figure 1, the allele model meta-analysis for rs2377422 showed a significant association with ACPA-negative RA under a fixed effects model (ORoverall = 1.17, 95% CI 1.06–1.30, P = 0.003) but not in random effects model (ORoverall = 1.13, 95% CI 0.93–1.36, P = 0.23, data not shown), due to a significant heterogeneity observed across different ethnic groups (Phet = 0.02, I2 = 67%).