HLA-DRB1 and rheumatoid arthritis: As shown in Table 5, the combination of homozygous PADI4 haplotype and HLA-DRB1 SE alleles significantly increased the risk in patients with RA (for non-erosive RA (OR 14.47, 95% CI 7.11 to 29.45); for erosive RA (OR 12.98, 95% CI 7.97 to 21.14)).