The diagnostic value of MR-proANP was confirmed in the BACH trial, which included 1641 patients with acute dyspnea, where MR-proANP was found to be as useful as B-type natriuretic peptide (BNP) in the diagnosis of acute HF and appeared to improve diagnostic accuracy in the BNP grey zone (levels between 100 and 500 pg/mL) and in patients with obesity [7]. This evidence concerns the gene NPPA and hydrops fetalis.