In a validation cohort of 150 individuals, including 44 with HF, 32 with chronic obstructive pulmonary disease (COPD), 59 with other causes of dyspnea, and 15 healthy controls, the authors quantified 17 candidate miRNAs and compared their diagnostic performance with that of established biomarkers: NT-proBNP (AUC = 0.896) and high-sensitivity troponin T (AUC = 0.750). The gene discussed is NPPB; the disease is hydrops fetalis.