While NT-proBNP is thought to be inert without any physiological function, BNP is biologically active and is responsible for several compensatory mechanisms in HF such as an increase of urine production and sodium excretion, a decrease of the aldosterone level, a lowering of the blood pressure and a lowering of the pulmonary capillary wedge pressure.17,18 BNP in physiological concentrations has too little effect to restore euvolemia but BNP is studied as a potential therapeutic agent in HF.19–22. The gene discussed is NPPB; the disease is hydrops fetalis.