Erosive rheumatoid factor negative and positive rheumatoid arthritis are immunogenetically similar

Objective. The relationship between rheumatoid factor positive (RF+) and rheumatoid factor negative (RF-) rheumatoid arthritis (RA) is controversial. We sought to determine whether the HLA genes conferring susceptibility for erosive RF + RA are also prevalent in patients with erosive RF - RA. Methods. DNA-based HLA typing for DRB1, DQB1, and DPB1 was performed on 16 consistently RF- patients with erosive RA. Results. Thirteen of 16 (81%) RF - RA patients had the HLA susceptibility genes DRB1 *0401, *0404, or *0101, which are associated with RF + RA, as compared to 46% of normal controls (p = 0.017). By contrast, no associations with HLA-DQB1 and HLA-DPB1 alleles were apparent. Conclusion. Specific HLA susceptibility alleles are prevalent in patients with erosive RA, regardless of RF status, suggesting a similar immunogenetic basis for RA in these patients.