Polymorphisms and functional activity in superoxide dismutase and catalase genes in smokers with COPD.

Increased oxidative stress has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). This study investigated the risk of COPD and the substitution of alanine 16 with valine (Ala16Val) polymorphism of manganese-superoxide dismutase (Mn-SOD) and the cytosine to thymidine transition of nucleotide -262 (-262C>T) polymorphism of the catalase gene, and the activity of erythrocyte SOD and catalase. The subjects were stable COPD patient ever smokers (n = 165) and healthy controls, matched for age and cigarette consumption. Genotyping of Mn-SOD at Ala16Val and the catalase gene at -262C>T was performed, and the functional activity of SOD and catalase in erythrocytes determined. There were no significant differences in the distribution of the different genotypes or allele frequencies between patients and controls for both the Mn-SOD and catalase genes. Among healthy controls or COPD patients, no differences were observed in erythrocyte SOD and catalase activity, irrespective of genotype. Significantly higher erythrocyte catalase activity was found in COPD patients than in healthy controls. The T/T catalase genotype and Ala/Ala Mn-SOD genotype were uncommon in the present Chinese population. The increase in erythrocyte catalase activity in Chinese patients with chronic obstructive pulmonary disease probably indicates dysfunction of the oxidant/antioxidant defence system, but it is unclear whether this increase is compensatory or a pathogenic factor.