EDA and hydrops fetalis: Evidence from humans and mice indicates that some molecular signals are involved in the process of HF morphogenesis, including noggin, Wnt, sonic hedgehog (SHH), bone morphogenetic proteins (BMP), fibroblast growth factor (FGF), anhidrotic ectodermal dysplasia (Eda), and transcription factors [7,8,9,10,11,12].