HLA class II molecules particularly HLA-DRB1 alleles are known to be present in RA patients.1 Recently, Proteus mirabilis has been implicated in the aetiopathogenetic mechanism of RA.2 Combination of smoking and HLA-DRB1 shared epitope alleles (SE) was shown to increase the risk of developing RA.3 RA is affecting about 1-2% of populations depending on the geographical distribution in the world. Here, HLA-DRB1 is linked to rheumatoid arthritis.