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Behçet's disease (BD), also known as the Silk Road disease, is a blinding inflammatory disorder of young adults found predominantly between the Mediterranean basin and the Orient, and is strongly associated with the major histocompatibility complex (MHC) antigen HLA-B51. In this article we review the history of Behçet's disease since its first description by Hippocrates, the development of the trading routes collectively known as the Silk Road and the effect of population movement on the distribution of HLA-B51. The global distribution of this antigen among healthy control populations bears a striking similarity both to the ancient trading routes and the distribution of Behçet's disease, suggesting a genetic risk that migrated in parallel with population movement between the Mediterranean and Asia. However, certain indigenous Amerindian peoples have a high prevalence of HLA-B51 but no reported cases of BD. Furthermore, a clear genealogical relationship exists between eastern, but not central, Siberian populations with the Amerindians. Since a high level of recombination within the MHC is known to have occurred in these eastern populations before their migration into Beringia, we suggest that disruption of genetic loci in linkage disequilibria with HLA-B51 may be one reason for the absence of disease in these high HLA-B51-bearing populations. However, a contributory influence of environmental factors is not excluded by this data, and the wide variation that exists in relative risk of HLA-B51 even within Europe would support other non-genetic risk factors on the Silk Road which may be absent, or non-contributory to disease, in the Americas.

Application of multiplex bead immunoassays has allowed us to identify distinct patterns of cytokines that relate to both clinical disease and the cellular infiltrates present. Bioinformatics analysis allowed identification of cytokines that differentiate idiopathic uveitis from noninflammatory control AqH and are likely to be important for the pathogenesis of uveitis.

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Multiplex bead analysis allows the measurement of multiple mediators from a single vitreous sample. The data confirm patterns of mediators previously described in different vitreoretinal conditions. In addition, LIU mediator levels correlate with duration of treatment and time after cataract surgery.

This novel study demonstrated that ocular barrier epithelial cells express the machinery for vitamin D3 and can produce 1,25(OH)2D3. We suggest that vitamin D3 might have a role in immune regulation and barrier function in ocular barrier epithelial cells.

These results suggest that a GIMAP cluster is a novel susceptibility locus for BD, which is involved in T-cell survival, and T-cell aberration can contribute to the development of BD.

Objective Experimental evidence suggests that inappropriate regulation of tumor necrosis factor α (TNFα) may play a role in the pathogenesis of Behçet's disease (BD). This is supported by recent reports highlighting the efficacy of anti‐TNFα agents in the treatment of this disease. The TNF gene is encoded in the class III region of the HLA complex adjacent to HLA–B. This genetic proximity to a gene that is already widely implicated in disease susceptibility led us to investigate the association between TNF promoter polymorphisms and susceptibility to BD. Methods We studied 133 UK white Caucasoid patients with BD and 354 healthy controls. We attempted to dissect the contribution of individual polymorphisms in this gene‐dense region by linkage disequilibrium mapping across 6 adjacent genes. Results We report a novel association with the TNF promoter allele TNF‐1031C. Subsequent analysis identified 2 extended HLA haplotypes associated with BD. One of them contained the previously recognized susceptibility gene HLA–B*51, while the other was defined by HLA–B*5701. Both of these haplotypes contained the TNF promoter polymorphism −1031C, an allele that was associated with disease even in individuals who did not carry either HLA–B*51 or HLA–B*5701. Conclusion The TNF‐1031C allele is independently associated with susceptibility to BD in Caucasoid patients. Further studies will be required to determine the functional effects of this polymorphism, its influence in disease pathogenesis, and its role in other ethnic groups.