LEF1 and hydrops fetalis: Wnt and BMP signals from the cortical hem, roof plate and/or meninges are essential for HF development (Galceran et al., 2000; Lee et al., 2000; Machon et al., 2007; Choe et al., 2013), and these induce the expression in the medial pallium of several transcription factors important for different aspects of HF development, such as Lhx2 (Porter et al., 1997; Bulchand et al., 2001; Monuki et al., 2001; Vyas et al., 2003), Lef1 (lymphoid enhancer factor 1) and other TCF transcription factors (Galceran et al., 2000; Choe et al., 2013).