Association of ERAP1 and IL23R Gene Polymorphisms with Susceptibility and Clinical Manifestations of Spondyloarthritis in Tunisian Patients.

INTRODUCTION: Among the non-HLA loci, ERAP1 and IL-23R gene polymorphisms have been implicated in spondyloarthritis (SpA). This study aimed to determine their association in a Tunisian cohort and to assess their influence on disease characteristics. METHODS: We genotyped 100 SpA patients and 100 sex- and region-matched healthy controls using real-time PCR for ERAP1 (rs27044, rs30187) and IL-23R (rs7530511) SNPs. Allelic, genotypic, and haplotypic frequencies were compared. HLA-B27 status and data on clinical and paraclinical characteristics of the disease were collected. RESULTS: The mean age was 42.8 ± 12.2 years, with a sex ratio M/F = 1.7. HLA-B27 was found in 55.6% of patients (OR = 25, 95% CI [9.5-69.2]; p < 0.001). None of the SNPs of ERAP1 or IL- 23R was associated with SpA susceptibility, even after analysis according to HLA-B27 status. Clinically, the rs7530511 G variant was associated with disease activity. In HLA-B27-positive patients, rs27044 C and rs30187 T alleles were significantly associated with less active forms of SpA. In multivariate analysis, the rs30187 T allele was independently associated with the risk of psoriasis. The rs30187 C allele and the C-C haplotype of ERAP1 were independent factors for quality-of-life impairment. DISCUSSION: Although these SNPs showed no relationship with disease susceptibility, some were associated with disease severity and comorbidities and are therefore likely to contribute to clinical expression rather than disease predisposition. CONCLUSION: The studied polymorphisms of ERAP1 and IL-23R were not associated with SpA susceptibility in Tunisian subjects. HLA-B27 status did not appear to influence these relationships, but some SNPs may influence clinical manifestations.