CTLA4 and Behcet disease: Considering the role of T cells in BD, the CTLA-4 49 A/G single nucleotide polymorphism could be associated with this disease, so in the present study, we aimed to investigate if +49 A/G single nucleotide polymorphism of CTLA-4 gene confers susceptibility to BD and its effect on the level of sCTLA-4 protein and their potential association to the main clinical features of the disease in Egyptian population.