The high level of ROS in vitiligo is a consequence of abnormal production and of reduced activity of antioxidant enzymes comprising catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione S-transferase (GST), thioredoxin reductase (TR), and methionine sulfoxide reductases (Msrs) [35,36]. The gene discussed is CAT; the disease is vitiligo.