Ectopic HFs did not originate from LGR5+ stem cells in the lower HF, even though they are β-catenin sensitive (Jaks et al., 2008), and LGR5+ cells in the new HFs arose from LGR5- cells, suggesting that ectopic HFs indeed recapitulate the process of HF development, which has been proposed previously (Baker et al., 2010, Lo Celso et al., 2004, Silva-Vargas et al., 2005). Here, LGR5 is linked to hydrops fetalis.