The pathogenesis of HF is complex, as different neurohormonal systems are involved, including the overactivation of deleterious pathways, such as the renin-angiotensin and the sympathetic nervous systems, but also the inhibition of protective pathways, such as the natriuretic peptides system and the nitric oxide-soluble guanylate cyclase-cGMP system [16,17,18,19]. This evidence concerns the gene REN and hydrops fetalis.