Major histocompatibility complex variants and articular disease severity in rheumatoid arthritis.

In the light of associations previously described between DR4, DQw7, the C4B null allele and Felty's syndrome, and between Dw14, the C4A null allele and rheumatoid vasculitis, we have looked for associations between these and other DRB1, DQB, DQA and C4 encoded variants, and articular disease severity assessed radiologically in 119 subjects with RA but without major extra-articular features. The association of DR4 with more severe disease and DR1 and DR2 with mild disease was confirmed but no associations were found between the presence of DQw7, Dw14, C4A or C4B null alleles and articular disease severity. This suggests that the associations noted previously between these markers and extra-articular disease features of Felty's syndrome or rheumatoid vasculitis are unlikely to reflect an overall effect on disease severity but more likely to represent associations with these particular extra-articular disease subsets.