Such situations would include individualizing ESA therapy based upon the following scenarios: initiating ESA therapy in adult patients with stage 5 CKD requiring dialysis when Hb is > 9.0 and < 10.0 g/dL or CKD patients not requiring dialysis with Hb concentration <10.0 g/dL after considering the rate of decline in the Hb concentration, their prior response to iron therapy, the risk of needing a transfusion, the risks related to ESA therapy, and the presence of symptoms attributable to anemia. Here, GSTM1 is linked to anemia (phenotype).