HLA-DRB1 frequency in patients with familial and sporadic rheumatoid arthritis in north east of Iran.

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the joints that has a strong correlation with HLA-DRB1. Family history is considered a known risk factor for RA. The aims of this study were to compare the frequency of HLA-DRB1 alleles between patients with sporadic and familial RA and also between healthy controls with RA patients (sporadic and familial) and clarify if familial RA is more severe than sporadic RA. This study included 129 consecutive patients with sporadic and 48 cases with familial (first-degree siblings) RA who visited a rheumatology unit. Demographic data, including extra-articular involvement, mean disease activity according to DAS28 (ESR) criteria, and main laboratory findings, were compared between patients with sporadic and familial RA. HLA-DRB1 typing was carried out using the PCR-SSP method, and the frequency of each allele was determined in all cases and compared with the results of HLA-DRB1 frequencies in 72 healthy controls who were previously reported by our group in northeast Iran. Patients with sporadic and familial RA were matched in age and sex, most of the cases in both groups were females. The mean age of patients was 45 years. Ocular involvement was the most frequent extra-articular manifestation of our patients. There was no significant difference between the two groups in visual analogue scale (VAS) index, number of inflamed or tender joints, extra-articular involvements, and main laboratory findings. HLA-DRB1* 01 (55 %), 04 (48 %), and 03 (43 %) alleles were the most frequent alleles in both sporadic and familial diseases. The frequency of HLA-DRB1*11 and HLA-DRB1*13 was significantly higher in normal participants compared with RA (p = 0.001). There was no significant difference in the HLA-DRB1 allele's frequency between sporadic and familial RA. Therefore, familial aggregation was not associated with RA severity.