In addition, selenium-dependent glutathione peroxidases, especially GPx1 and GPx4, are also located in the mitochondria, where they detoxify H2O2 generated from the dismutation of superoxide and lipid peroxides, respectively, using GSH as a cofactor [10,11,12], and a decrease in GPx4-GSH is intimately associated with ferroptosis, an iron-dependent cell death seen in diabetic retinopathy [13,14]. The gene discussed is GPX4; the disease is diabetic retinopathy.