We suggest that the decreased HF matrix cell proliferation could account for the awl3 medulla cell disorganization and the changes in zigzag number and size on dermal Blimp1 deletion, two defects associated with perturbations in DP cell number or signaling (Chi et al., 2013a, Enshell-Seijffers et al., 2010). Here, PRDM1 is linked to hydrops fetalis.