LGR5 and hydrops fetalis: Although the HF stem cells located directly above the follicle bulge (Lgr6+) contribute 10% of neogenic HF within a wound5, Gli1+ cells become Epi-SCs during wound healing48, Lrig1+ cells dominantly contribute to de novo HF regeneration in reconstitution analysis49, and the HF stem cells beneath the follicle bugle (hair germ, Lgr5+) repopulate other stem cell compartments and extensively participate in wound re-epithelialization4, 50, 51, 52, their contribution to WIHN has not been fully elucidated.