Antioxidant enzymes

rs4880 (SOD2, Ala16Val): mitochondrial manganese superoxide dismutase converts superoxide into H₂O₂. The variant sits in the mitochondrial targeting sequence; the Ala allele is imported efficiently and yields about 40 percent more active enzyme there, while the Val allele is partly arrested in the inner membrane and degraded (Sutton 2005). rs1050450 (GPX1, Pro198Leu): glutathione peroxidase 1 further breaks down H₂O₂; the Leu allele goes along with lower enzyme activity (Arsova-Sarafinovska 2008). rs1001179 (CAT, catalase): a direct H₂O₂ detoxifier; the effect allele lowers expression. rs1800566 (NQO1, Pro187Ser): protects against quinone toxicity; the T allele contributes substantially to population variation in enzyme activity, and homozygous carriers have very low residual activity (Lajin 2013).

The four markers do not measure enzyme activity or form a validated measure of oxidative stress. Environment, tissue, cell state and other genetic factors affect these processes. The profile cannot establish an individual's sensitivity to exposures or a benefit from antioxidant supplements.

The functional effects of the individual variants are documented; their disease associations are inconsistent by population and should not be over-interpreted. Genome shows the markers as technical evidence.