Résumé
OBJECTIVE: Behcet? disease (BD) is a chronic inflammatory disorder affecting several organs. The etiology of BD remains unclear, although genetic factors, infectious agents, and immune mechanisms have been studied. The association of BD with certain genetic factors, especially HLA-B51 antigen, is well known in some geographical areas. Nevertheless, the familial occurrence of BD is rare. In this paper, HLA phenotype was evaluated in one family member showing the clustering of BD. METHODS: The serological tissue typing of HLA class I and class II antigens was performed by standard National Institutes of Health microlymphocytotoxicity method in seven family members in which four siblings were affected by BD. The diagnosis of BD was established by the criteria of the International Study Group of BD in these four siblings. RESULTS: In this family study, all members had HLA-A2 and DQ3 antigens. Although HLA-B51 antigen was positive in six out of seven family members, BD was developed in three of the six having HLA-B51 antigen. Three siblings had the exact same HLA phenotype. However, only one person had BD among three siblings with identical HLA phenotype. In addition, all siblings who developed erythema nodosum-like lesion had HLA-B51 antigen. CONCLUSION: This family suggests that the familial clustering of BD may not be explained solely by a susceptible HLA phenotype. The environmental factor or other genetic factors besides HLA-B51 might play a role in the development of BD. Furthermore, more studies and information will be needed to clarify the role of A2 and DQ3 antigens in BD.