HLA-DRB1 genes and disease severity in rheumatoid arthritis in Turkey

Objective: Association with human leukocyte antigen (HLA)-DRB alleles, implicated in the aetiopathogenesis of rheumatoid arthritis (RA), is found to be different in various ethnic groups. This study aimed to investigate DRB1 alleles in RA patients in Turkey, and to examine the effect of these alleles on disease severity. Methods: We performed PCR-based DRB1 genotyping of 104 RA patients recruited from clinical settings and 110 healthy controls. HLA DRB1 alleles frequencies in RA patients and healthy controls were determined. Phenotype frequencies of patients and controls were compared. Disease severity was assessed by radiological erosion, presence of extra-articular involvement, and functional index. Results: Significant differences were in the frequencies of DRB1*04 (46.2% versus 20.9%, p<0.001), DRB1*0401 (10.6% versus 0%, p<0.001), DRB1*0405 (8.7% versus 0%, p=0.001), DRB1*0404 (15.4% versus 3.6%, p<0.01), DRB1*01 (21.2% versus 10.9%, p<0.05) and DRB1*0101 (16.3% versus 5.5%, p = 0.01) between RA patients and controls. HLA-DRB1 alleles did not show any association with seropositivity, extra-articular involvement, radiological erosion, or functional index. Conclusion: Our results suggest that the HLA-DRB1 alleles, particularly HLA-DRB1*04 and subtypes, were associated with RA.