The HF defects resulting from Blimp1 deletion are likely to be due, at least in part, to downregulation of β-catenin in the DP because β-catenin signaling regulates HF growth and cycling (Enshell-Seijffers et al., 2010, Kaushal et al., 2015, Tsai et al., 2014). Here, PRDM1 is linked to hydrops fetalis.