Similar Disorders

There are several disorders that have patterns of symptoms that overlap with those of Behçet’s. In the absence of a test to confirm Behçet’s, this can make diagnosis quite difficult.

This is especially true when symptoms are making people unwell while these disorders are in the early stages and have not yet developed a characteristic set of symptoms. However, most of them have markers, and appropriate tests and investigations will identify them, or the natural course of the illnesses over time will enable a diagnosis to be made. They can then be distinguished from Behçet’s.

Pathergy

The exaggerated reaction of tissues to damage, known as pathergy, is the nearest thing to a test for Behçet’s at present. As pathergy is not always present in some people with Behçet’s and often only intermittently present in patients who do have it, it is usually used only to confirm a diagnosis when the other symptoms make it likely.

Tissue-type HLA-B51

There has been some interest in the tissue-type marker B51, as a statistical link exists between people with Behcet’s being positive for that type and having inflammation in the eyes. However, this only applies to people from Japan, China and the Middle East and is not apparent in people of Western ethnic origins. This limits its usefulness as a diagnostic marker. Research interest is now directed away from the B51 locus to adjacent areas on the same chromosome, with the possibility that there may be a malfunction in a gene or genes which form part of the immune system there.