TFAP2A and hydrops fetalis: Additionally, a number of new functional pathways regulating HF formation were also activated, including the negative regulation of the TFAP2 (AP-2) family of transcription factors24, WNT ligand biogenesis and trafficking8, GLI protein binding to promoters of Hh responsive genes to promote transcription34, and binding of TCF/LEF:CTNNB1 to target gene promoters35 (Fig. 1E).