The association of polymorphisms in CTLA-4 and CD28 with some immune vasculitides, such as systemic lupus erythematosus (SLE) and Behçet's disease has been reported.
The frequency of IVS3 +17TC genotype of the CD28 gene was significantly increased in BD patients compared to controls (43.6% vs. 31.2%, OR = 1.663, 95% CI = 1.033-2.679, P = 0.039).