HFrEF : 1) LVEF < 35% 2) NYHA II-IV 3) receiving optimal treatment for HF CKD : CrCl < 90 mL/min iron-deficiency anaemia : 1) Hb < 12.5 (men) and Hb < 11.5 (female) 2) Serum ferritin < 100 ng/mL and/or TSAT < 20%. This evidence concerns the gene GSTM1 and chronic kidney disease.