Van der Woude syndrome (VWS, OMIM #119300) is a dominantly inherited developmental disorder characterised by pits and/or sinuses of the lower lip, cleft lip with or without cleft palate (CL/P), isolated cleft palate (CP), bifid uvula (BU), and hypodontia (H).1–3 Cleft lip deformity is established during the first 6 weeks of life due to failure of fusion of maxillary and medial nasal processes or to incomplete mesodermal ingrowth into the processes. Palatal clefts result from failure of fusion of the palatal shelves that normally change from a vertical to horizontal position and fuse during the sixth to ninth weeks of gestation.
Ghassibé, M., Revencu, N., Bayet, B., Gillerot, Y., Vanwijck, R., Dumoulin, C., & Vikkula, M. (2004). Six families with van der Woude and/or popliteal pterygium syndrome: all with a mutation in the IRF6 gene. Journal of Medical Genetics, 41(2), 1-5. https://doi.org/10.1136/jmg.2003.009274 (Original work published 2004)