According to “The National Kidney Foundation Disease Outcomes Quality Initiative” (NKF/KDOQI), “Kidney Disease Improving Global Outcomes” (KDIGO), and “European Best Practice Guidelines” (EBPG), anemia is defined as a target hemoglobin (Hb) <13.5 g/dl in adult males/postmenopausal females, <12.0 g/dl in premenopausal females, and <5th percentile for children [2–4]; alternatively, the target Hb should generally be <11.0 g/dl [5, 6]. The gene discussed is GSTM1; the disease is anemia (phenotype).