We have demonstrated previously that ablation of Pofut1, a critical component of Notch signaling, in HF lineages resulted in disrupted telogen‐anagen transition.20Pofut1‐deficient HFs turn into cysts at the second hair cycle, which prevented studying how the Notch‐Hes1 axis participates in hair cycle homeostasis. Here, HES1 is linked to hydrops fetalis.