Objective: To investigate the previously reported association of HLA-B51 with the manifestations and severity of Behçet's disease (BD).
Methods: The study group consisted of 148 consecutive BD patients (89 male, 59 female) with a minimum disease duration of 5 yr followed up at an out-patient BD clinic in a tertiary referral centre. The patients were classified into three severity groups (mild, moderate, severe) using a modified form of the BD total activity index. HLA-B alleles were determined by DNA amplification using the polymerase chain reaction and sequential hybridization with sequence-specific oligonucleotide probes.
Results: The frequencies of genital ulceration [odds ratio (OR)=3.1, 95% confidence interval (CI) 1.3-7.5], skin findings (erythema nodosum, folliculitis or acne-like lesions) (OR=4.4, 95% CI 1.1-17.7), a positive skin pathergy test (OR=3.4, 95% CI 1.1-10.9) and eye disease (OR=1.8, 95% CI 0.9-3.7) were all higher in B*51-positive patients. By contrast, no significant association was observed between B*51 positivity and a severe disease course, and B*51 homozygosity did not exhibit a prominent association with the severity of BD. Male sex was found to be the strongest determinant of the severity of BD by logistic regression analysis (OR=4.7, 95% CI 1.9-11.2).
Conclusion: HLA-B*51 does not exhibit a strong association with a more severe disease course in BD. The involvement of other genetic and/or environmental factors seems to be required and to be more important than B*51 for the progression of BD.