However, as the function of NCX is also affected by Na+, and intracellular Na+ is increased in both human HF and models of HF (Bers and Despa, 2006), Ca2+ extrusion through NCX could be impaired due to Na+-loading observed in end stage HF (Louch et al., 2010; Li et al., 2012). This evidence concerns the gene TLX2 and hydrops fetalis.