In conclusion, in HR overexpressing hairpoor mice, the HFSC quiescence is not maintained due to decreased HFSC niche signals including Fgf18, Bmp6, and Sfrp1. This leads to the telogen-to-anagen transition of HFs at the telogen phase, and proliferation of HF occurs through activation of the Wnt signaling in the hairpoor mouse (Fig. 6h). Here, BMP6 is linked to hydrops fetalis.