HLA-DRB1 and rheumatoid arthritis: Association between RA and HLA-DRB1 alleles *04, *07, and *11 was detected by comparison of RF-positive and RF-negative RA cases [see Table S13 in Additional data file 1], whereas after correction for multiple testing, alleles *04 and *07 still met our criteria for significance (Pcorr = 0.018 for both alleles).