Behçet's disease: familial clustering and immunogenetics.

Behçet's disease (BD) is a relapsing, multisystemic inflammatory disorder, characterized by major symptoms consisting of recurrent orogenital ulcerations, eye and skin lesions. Other clinical features may include musculoskeletal, vascular, gastrointestinal, renal, cardiopulmonary or neurological involvement. Vasculitis affecting all types and sizes of blood vessels is the main histopathologic process, in a third of cases complicated by thrombosis. The etiopathogenesis is presently unknown, but BD likely represents the result of a peculiar immune response to hitherto unidentified environmental factors in genetically predisposed subjects. The prevalent distribution in a specific geographical area spanning the Mediterranean basin and Asia, the close association with human leukocyte antigen B*51 in different ethnic groups, and the familial clustering of BD are hallmarks accounting for the strong contribution of a genetic background. The BD familial aggregation is characterized by both genetic anticipation and higher prevalence in childhood patients, likely defining a subset with stronger immunogenetic influences. Polymorphisms in genes encoding for host effector molecules may have a supplementary role in disease susceptibility and/or severity. The contribution of prothrombotic mutations and polymorphisms in the pathogenesis of BD thrombosis is controversial. In this paper, the available reports on BD familial clustering and the evidence for the role of immunogenetic predisposing factors are reviewed.