DKK3 and hydrops fetalis: Although bulge cells express secreted WNT inhibitors such as Dickkopf 3 (Dkk3) and secreted frizzled-related protein 1 (Sfrp1) (Kandyba et al., 2013; Lim et al., 2016), usually associated with quiescent HF, the former one was found in the WNT-inactive internal bulge in the growth phase of the hair cycle (Lim et al., 2016).