Clusters in Behçet's syndrome.

Clustering is an important clinical feature of Behçet's syndrome (BS) and may have pathogenetic and therapeutic implications. Recent and previous studies on BS phenotype differ substantially in terms of methodology. Correlation matrices and factor analyses were not efficient enough to uncover clusters. Clustering patterns may change according to demographic factors such as age and sex. Clustering patterns may also be profoundly influenced by the misperception of symptoms that are assumed to be secondary to BS, when, in fact, they represent manifestations of BD mimics. This can give rise to misleading conclusions and should be kept in mind when interpreting data obtained by clustering or other phenotype analyses of BS. A true geographical/racial variability in disease expression could be studied in a multinational consensus cohort. Pathogenetic studies in separate clusters of BS have still been lacking.