Mice lacking the Wnt9b gene exhibited cleft lip with cleft palate, which resulted from a retarded outgrowth and subsequent failed fusion of the nasal processes (NP) and maxillary process of branchial arch 1 (MxBA1) due to significantly diminished WNT/β-catenin signaling (Jin et al., 2012). Here, WNT9B is linked to cleft palate.