FN1 and Schnyder corneal dystrophy: It appears that cytokine-chemokine network is crucially involved in the pathogenesis of vaso-occlusive events which are described as important clinical symptoms of SCD by several possible mechanisms as following: (a) activates endothelium, (b)facilitates adhesion of RBCs and neutrophils to the endothelium, (c) causes attachment of neutrophils to the plasma fibronectin, (d) involves in progression of vascular intimal hyperplasia, (e) activates platelets, (f) induces the endothelin production, and (g) finally dysregulation of apoptosis.