Replication of GWAS-identified systemic lupus erythematosus susceptibility genes affirms B-cell receptor pathway signalling and strengthens the role of IRF5 in disease susceptibility in a Northern European population.

Objective. A large number of genes, including several not previously implicated in SLE susceptibility, have recently been identified or confirmed by genome-wide association studies (GWAS). In this study, we sought to replicate some of these results in Finnish SLE patients (n = 275) and control individuals (n = 356).Methods. We genotyped 32 single nucleotide polymorphisms (SNPs) in 12 of the best-supported GWAS-identified SLE genes and loci. We further investigated gene–gene interactions between the loci included in the study.Results. The strongest evidence of association was found at the IRF5-TNPO3 locus, with the most significant P-value being 2.0 × 10−7 and an odds ratio of 1.95 (95% CI 1.51, 2.50). Association between SLE and TNFAIP3, FAM167A-BLK, BANK1 and KIAA1542 was also confirmed, although at a lower significance level and contribution to individual risk. No significant association was found with 1q25.1, PXK, ATG5, ICA1, XKR6, LYN and SCUBE1. Furthermore, no significant gene–gene interactions were detected.Conclusion. Replication of previous GWAS findings across diverse populations is of importance to validate these associations and to get a better understanding of potential genetic heterogeneity between populations in SLE susceptibility. Our results attest the importance of B-cell receptor pathway and IFN signalling in SLE pathogenesis. [ABSTRACT FROM PUBLISHER]