HFrEF: 1) NYHA class II with LVEF ≤40% within the preceding 6 months 2) NYHA class III and LVEF ≤45% within the preceding 6 months 3) use of optimal HF drugs for ≥4 weeks without dose changes for ≥2 weeks Iron deficiency anemia 1) Hb <12,0 g/L in females and < 13,0 g/L in males 2) Ferritin <100 ng/L or 100-300 ng/L 3) TSAT <20%. The gene discussed is GSTM1; the disease is anemia.