IRF6 and cleft palate: Mutations in IRF6 cause Van der Woude's, along with popliteal pterygium (Leslie et al., 2015), and recent research suggests that mutations surrounding the gene may be involved in non-syndromic cleft palate (Zucchero et al., 2004; Rahimov et al., 2012; Pegelow et al., 2014).