SAG (S-antigen visual arrestin) encodes a protein that plays a critical role in visual signal transduction within retinal photoreceptor cells. The protein binds to photoactivated, phosphorylated rhodopsin (RHO) and terminates rhodopsin signaling by competing with G-proteins for the same binding site on rhodopsin, effectively shutting down the visual signal cascade. SAG may also function to prevent light-dependent degeneration of retinal photoreceptor cells 1. Mutations in the SAG gene cause autosomal recessive Oguchi disease type 1, a rare form of congenital stationary night blindness characterized by abnormal fundus appearance and night vision defects 1. Clinical studies have identified both novel and previously reported pathogenic variants in SAG, including nonsense mutations (p.R193*) and canonical splice site mutations (c.649-1 G > C), which disrupt normal protein function 1. The identification of SAG gene variants in Egyptian families has expanded the mutation spectrum and reinforced the gene's pathogenic role in Oguchi disease, providing a foundation for genetic diagnosis and counseling in affected populations.