GSR and anemia (phenotype): The findings in this study are: (1) Plasma AOPP is a valuable oxidative stress biomarker of anaemia and clinical malaria infection in children two years old living in a malaria endemic area; (2) Preceding levels of AOPP predict to some extent the development of anaemia in children two years old; and (3) Variants in GCLC, GSR and HMOX1 genes are associated with the host oxidative stress status, which was evidenced by their associations with AOPP levels.