H2O2 increased iron concentration in retinal pigment epithelial cells via the BMP6/SMAD/hepcidin axis, resulting in age-related macular degeneration [41].Inhibitory SMAD7 is a key repressor of hepcidin, the master regulator of systemic iron homeostasis [42]. The gene discussed is SMAD7; the disease is age-related macular degeneration.