The aim of this study is to explore relationship between
HLA-DRB1 alleles and the susceptibility and clinical features of
rheumatoid arthritis (RA) in the south Tunisian population. We studied 142 RA patients and 123 controls matched for age, sex, and ethnicity.
HLA-DRB1 genotyping and
HLA-DRB1*04 subtypes were performed using polymerase chain reaction/sequence-specific primers. Association was assessed based on the χ (2) test and odds ratio with 95% confidence interval. For multiple comparisons, p value was corrected (p (c)) with Bonferroni test. Two alleles,
HLA-DRB1*04 (p=0.045, p(c)=NS) and
HLA-DRB1*10 (p=0.021, p(c)=NS), were found to have increased frequencies in RA patients compared to controls. In contrast
HLA-DRB1*08 allele was found to have a decreased frequency in patients compared to controls (p=0.044, p(c)=NS). Molecular subtyping of the most prevalent allele (DRB1*04) revealed increased frequencies of
HLA-DRB1*04:05 in patients compared to controls (p=0.013, p(c)=NS) whereas
HLA-DRB1*04:02 showed a protective effect (p=0.005, p(c)=0.04). Moreover, stratified analyses indicated statistically significant associations between
HLA-DRB1*04 allele and anti-
cyclic peptides antibodies positivity (ACPA(+)) and
rheumatoid factor positivity (RF(+); p(c)=0.03, for both subgroups), HLA-DRBI*10 and ACPA(+) and the presence of another
autoimmune disease (p(c)=0.05 and p(c)=0.007, respectively), and
HLA-DRB1*04:05 and RF(+) and erosion (p(c)=0.005 and p(c)=0.049; respectively). A significant decrease in the frequency of the DRB1*04:02 allele was observed in patients with ACPA(+) and RF(+) subgroups (p(c)=0.04 and p(c)=0.02, respectively). Our results showed that there was a trend of positive association of
HLA-DRB1*04 and
HLA-DRB1*10 with RA as such and significant associations with the disease severity in the south Tunisian population.