Objective: To determine the association of disease related HLA-DRB1 locus with disease severity and extraarticular features in Singaporean Chinese patients with rheumatoid arthritis (RA).
Methods: 70 patients with RA and 80 controls were typed for HLA class II alleles by the polymerase chain reaction-sequence specific oligonucleotide probe method.
Results: 56 patients (80%) had erosive disease; 51 were seropositive (73%), and 16 had extraarticular features (23%). Patients with HLA-DRB1*0405 had significantly higher prevalence of extraarticular features (43 vs 10%; p = 0.001) and erosions (93 vs 71%; p = 0.022) compared to those without the allele. There was also a greater frequency of seropositivity and joint surgery, and a higher number of second line agents used by patients with HLA-DRB1*0405 in comparison to those without, although the difference was not statistically significant.
Conclusion: HLA-DRB1*0405 is associated with the presence of extraarticular features and erosions in Singaporean Chinese patients with RA.