HLA-B5 Prevalence in Patients with Spondyloarthritis and Impact on Disease Phenotype: a Multicentric Case-Control Study.

Objective The study aimed to estimate the prevalence of HLA-B51 and HLA-B52 in Lebanese patients with spondyloarthritis (SpA) compared with healthy controls (HC). We further aimed to evaluate the impact of HLA-B51 on phenotype and identify the distribution of the alleles in the HLA-B locus.Methods A case-control study enrolled consecutive SpA patients from three rheumatology clinics in Lebanon, including axial (axSpA), peripheral SpA (pSpA), and psoriatic arthritis (PsA) and HCs from blood donors. Demographic and disease data were collected through interviews and file reviews, with testing of the entire HLA-B locus using molecular techniques. The prevalence of HLA-B51 and B52 was estimated in SpA patients vs controls. Prevalence comparisons were made, and logistic regression identified factors associated with HLA-B51 in patients.Results Data from 120 HCs and 86 SpA patients (65 axSpA, 15 pSpA, 6 PsA), mean age 25.6 and 46.4 years, respectively, showed a higher HLA-B51 prevalence in SpA (25.6%), especially axSpA (29.2%) vs HC (12.5%) (P = 0.016), and a numerically higher HLA-B52 prevalence (8.1% vs 4.2%, P = 0.230). HLA-B51 correlated with recurrent oral ulcerations (OR 7.99; 95% CI: 2.14, 29.84) and radiographic juxta-articular erosions (OR 7.65; 95% CI: 1.14, 38.03). HLA-B35 was the most dominant allele in both groups (18.7%), followed by HLA-B27 (15.7%) and HLA-B51 (13.4%) in SpA.Conclusion HLA-B51 was identified more frequently in patients with SpA compared with HC and was associated with recurrent oral ulcerations and juxta-articular radiographic erosions. Longitudinal studies are needed to determine whether this association indicates a disease overlap or might correlate with a specific SpA phenotype.