PAX9 and cleft palate: In recent years, genetic studies on cleft palate have shown that some candidate genes are related to an increased risk of CP, such as msh homeobox 1 (MSX1), paired box 9 (PAX9) [7], interferon regulatory factor 6 (IRF6), transforming growth factor alpha (TGFA), bone morphogenetic protein 4 (BMP4), fibroblast growth factor 8 (FGF8), fibroblast growth factor receptor 2 (FGFR1), forkhead box E1 (FOXE1) and so on [3,8].