To find out, we selected five candidate SNPs of antioxidant enzyme genes (MnSOD: rs4880 and rs5746136, GPX1: rs1800668, CAT: rs1001179 and rs769217), most of which have been linked to kidney diseases [20,21,22], to study each of their effects when combined with environmental melamine exposure on 8-OHdG and MDA, two biomarkers of oxidative stress, and NAG, a biomarker of renal tubular injury, in urine. This evidence concerns the gene SOD2 and kidney disorder.