Background rheumatoid arthritis (RA) is a complex polygenic disease. HLA-DRB1 alleles encoding the shared epitope (SE) are associated with RA susceptibility and severity. Recently HLA-DRB1 SE alleles has been reclassified into S1, S2, S3P and S3D groups.

Objectives assessed the impact of this new classification of the HLA-DRB1 SE⁺ in RA susceptibility and structural severity.

Methods serum and genomic DNA samples of 154 RA patients and 95 healthy controls were obtained. HLA-DRB1 genotyping and sub typing was performed by PCR- sequence specific probes (PCR-SSP). Rheumatoid factor (RF) and C-reactive protein (CRP) were quantified by nephelometry. ACPAs were detected by ELISA. Disease activity was assessed using the DAS28-VS and radiographic damage by Sharp Vander Heidje method

Results we found a positive association between RA susceptibility and S3P alleles (OR=2.94, 95% CI 1.82 to 4.84; p<7.10^-5) and S2 alleles (OR=2.71, 95%CI 1.047 to 8.17; p<0.04). In opposite, a negative association was found for S1 alleles (OR =0.58, 95% CI 0.37 to 0.89, p<0.01) and X alleles (OR=0.59, 95% CI 0.40 to 0.86; p<5.10^-3). No significant association was observed for the S3D class of alleles (13.9% vs 14.2%, p<0.93). Finally we didn’t observe any association between the HLA-DRB1 alleles and structural severity.

Conclusions According to the revised classification, RA susceptibility alleles in Algerian patients were S2 and S3P groups alleles but the protective alleles were S1 and X alleles. Our results support the hypothesis of a differential role played by different HLA-DRB1 allele groups in RA susceptibility and structural severity.

Disclosure of Interest None Declared