Several genes such as IL genes (IL-1A, IL-1B, IL-1 receptor antagonist, IL-2, IL-6, IL-10, IL-12B promoter, IL-17F, IL-18, IL-23R genes), tumor necrosis factor (TNF) genes, transporter associated with antigen processing (TAP) gene, intercellular adhesion molecule-1 (ICAM-1) gene, endothelial nitric oxide synthase (eNOS) gene, glutathione S-transferase gene, N-acetyltransferase gene, and vascular endothelial growth factor (VEGF) gene polymorphisms have been related to BD susceptibility. The gene discussed is NOS3; the disease is Behcet disease.