Alternatively, FGF23 may promote myocardial fibrosis and remodelling via activation of the renin–angiotensin–aldosterone system27 and may contribute to the development of anaemia28; we did observe a relatively strong inverse association between FGF23 and haemoglobin and treatment of iron deficiency in HF is known to result in reduction in FGF23 levels.29 The gene discussed is REN; the disease is hydrops fetalis.