TFAP2A and coloboma: Abrogation of genes encoding transcription factors implicated in POM development, such as zic2, lmx1b, and TFAP2A/tfap2a leads to lack of apposition of the ventral retinal lips and coloboma (Gestri et al., 2009; McMahon et al., 2009; Bassett et al., 2010; Lupo et al., 2011; Sedykh et al., 2017).