In HF PP1 protein levels are reported to be increased (Neumann et al., 1997; Huang et al., 1999) and expression of its inhibitor PI-1 decreased (El-Armouche et al., 2004), which should predict hypophosphorylation, as is reported for PLB (Huang et al., 1999; Dash et al., 2001) with residues T16 and T17 showing reduced phosphorylation (Schwinger et al., 1998; Huang et al., 1999). The gene discussed is PLN; the disease is hydrops fetalis.