The ESC guidelines for the management of HF define iron deficiency (ID) irrespective of the respective type as present when serum ferritin is < 100 ng/ml or when serum ferritin is of 100–299 ng/ml with transferrin saturation (TSAT) < 20%.10 Further, the guidelines recommend that “all patients with HF are periodically screened for anaemia and ID”. The gene discussed is TF; the disease is hydrops fetalis.