The HLA-BS phenotype was investigated in 235 patients with Behcet's di
sease and in 100 healthy persons. HLA-BS was more frequent in the pati
ents (77 vs. 30% p<0.001, relative risk=7.8). The frequency of HLA-BS
was higher in patients with genital ulceration than without (82.3 vs.
63%, p<0.01). Patients with thrombophlebitis showed a less frequent po
sitivity of HLA-BS antigen than the patients without thrombophlebitis
(50 vs. 79.2%, p<0.02). These results suggest that HLA-BS-related gene
s not only affect the development of Behcet's disease but also the occ
urrence of its clinical manifestations.