VWS is genetically heterogeneous with VWS1 (OMIM #119300) being caused by heterozygous mutations in IRF6 on chromosome 1q32.2 and VWS2 (OMIM #606713) by heterozygous mutations in GRHL3 on chromosome 1p36.11 (Peyrard-Janvid et al., 2014). The gene discussed is GRHL3; the disease is van der Woude syndrome 1.