To determine the association of disease related HLA-DRB1 locus with disease severity and extraarticular features in Singaporean Chinese patients with rheumatoid arthritis (RA).
70 patients with RA and 80 controls were typed for HLA class II alleles by the polymerase chain reaction-sequence specific oligonucleotide probe method.
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.
HLA-DRB1*0405 is associated with the presence of extraarticular features and erosions in Singaporean Chinese patients with RA.