GPX1 and chronic kidney disease: Furthermore, our findings in relation to other major antioxidant enzyme polymorphisms, such as GPX1, are also in concordance with a previously published study, which shows no link between the GPX1 polymorphism and CKD development [16], although in our study we demonstrated a greater than 3-fold increased risk of ESRD when the SOD2 Val/Val and GPX1 Leu/Leu polymorphisms were combined together.