The JET-STREAM (Japan Erythropoietin Treatment survey for STarting hemoglobin level in REnal Anemia Management) study was conducted to investigate the relationship between renal outcome and the Hb level at initiation of epoetin beta therapy, rather than the target Hb level, in non-dialysis CKD patients with anemia. The gene discussed is GSTM1; the disease is anemia (phenotype).