HLA-DRB1 and rheumatoid arthritis: In addition, the HLA-DRB1*04:01/*04:04 genotypes are risk alleles (odds ratios are ∼4.14 and ∼3.17, respectively) for RA (10) and the HLA-DRB1*15:01-DRB5*01:01 haplotype (up to 60% among Caucasians) is linked to multiple sclerosis (MS) (11).