The same ESC guidelines propose the measurement of the B-type natriuretic peptide (BNP) and/or N-terminal pro-BNP as an additional diagnostic criterion for HFmrEF and HFpEF, specifying that this cannot be useful to discriminate all three HF phenotypes because of its increase in other clinical conditions, including atrial fibrillation and renal failure, that compromise the interpretation of BNP and pro-BNP quantification [4]. The gene discussed is NPPB; the disease is hydrops fetalis.