Higher risk of uveitis and dactylitis and older age of onset among ankylosing spondylitis patients with <i><scp>HLA</scp>‐B*2705</i> than patients with <i><scp>HLA</scp>‐B*2704</i> in the Chinese population

Human leukocyte antigen (HLA)-B27 is closely associated with ankylosing spondylitis (AS). However, the exact correlation between HLA-B27 subtypes and AS manifestations remains unknown. This study aimed to investigate the correlation between HLA-B27 polymorphism and the clinical features of AS. This study included 846 patients with AS and 959 healthy controls. Direct sequencing was used to identify the HLA-B27 genotype. Clinical parameters, including age, age of onset, family history, low back pain, peripheral arthritis, hip joint involvement, dactylitis, uveitis, and sex ratio, were compared among patients with various HLA-B27 subtypes. In total, 741 AS patients (87.6%) and 39 healthy controls (4%) were HLA-B27-positive. The most prevalent subtypes were HLA-B*2704 (88%) and HLA-B*2705 (10.1%) in patients with AS. Compared with HLA-B*2704-positive patients, HLA-B*2705-positive patients demonstrated a significant increase in the incidence of uveitis (16% vs 6.13%, P = 0.002) and dactylitis (9.3% vs 3.8%, P = 0.028) and they had an older age of onset (22.9 ± 8.0 vs 20.7 ± 6.7 years, P = 0.028). Binary logistic regression analysis revealed that presence of uveitis was significantly associated with HLA-B*2705 (P = 0.008; odds ratio, 2.63; 95% confidence interval, 1.283-5.393). There were no significant differences in family history, low back pain, peripheral arthritis, or hip joint involvement among HLA-B27 subtypes. Specific HLA-B27 subtypes were positively associated with particular clinical features of AS. AS patients with HLA-B*2705 demonstrated an older age of onset and had a higher risk of uveitis and dactylitis than did AS patients with HLA-B*2704.