SNP rs17634369 was located approximately 22 kb upstream of the IKZF1 gene, where no other genes were mapped (Figure S7), and was in strong linkage disequilibrium with the SNP rs4917014 (D′ = 0.921, r2 = 0.773), which was previously identified as conferring susceptibility to systemic lupus erythematosus (SLE).28 There were no significant associations between previously validated SNPs for SLE and C pneumoniae IgA index value (Table S5). This evidence concerns the gene CD79A and systemic lupus erythematosus.