High concentrations of lipid-peroxidation products (salivary malondialdehyde (MDA), 8-isoprostanes) and oxidized nucleic-acid adducts (8-hydroxy-2′-deoxyguanosine) are also consistently observed in serum and saliva of patients with OLP, and there is a reduction in antioxidant defences (glutathione, superoxide dismutase, catalase, total antioxidant capacity) [10,11]. The gene discussed is CAT; the disease is oral lichen planus.