SOD activity has been determined also in plasma of COPD patients using assays based on the inhibition of red formazan dye formation, finding an increase of SOD activity [61], a decrease of SOD activity [32, 41] and no difference [70, 71] compared to controls, as well as no difference throughout the stages of the disease [47] (Table 1). The gene discussed is SOD1; the disease is chronic obstructive pulmonary disease.