Objectives. - Rheumatoid arthritis (RA) is a common, complex autoimmune disease known to be associated with inheritance of certain human leukocyte antigen (HLA)-DR alleles in different populations. This study investigated the association of DRB1 alleles in Kuwaiti patients with RA.

Materials and methods. - DRB1 alleles were analyzed in 47 Kuwaiti patients and 70 ethnically matched controls using a DNA-based sequence specific primer (SSP) method.

Results. - The frequency of DRB1*04 allele was higher in patients compared to the controls (P<0.012). The association with of HLA-DRB1*04 allele in our patients with RA was accounted for mainly by the seropositive group of patients (P<0.05). Moreover, five patients were homozygous for DRB1*4 compared to none in the controls. None of the other DRB1 alleles tested was significantly higher in the patients. All patients homozygous for the DRB1*04 allele were females. There was no statistically significant difference in the frequency of DRB1*04 allele in patients classified according to presence of erosive disease or extra-articular manifestations.

Conclusion. - Our results indicate that in Kuwaiti patients, RA is associated with the presence of DRB1*04 allele. The lack of association with severity or the phenotype of RA is not surprising since this is a hospital-based study where patients tend to have a more severe disease.