Our findings have medical relevance because ∼40% of patients in a family carrying a loss-of-function mutation in the YAP1 gene have been reported to have cleft palate/lip/uvula at birth (Williamson et al., 2014) and our results indicate that these mutations may be causative, as our mouse Yap/Taz knockouts produce strongly penetrant cleft palate and complete neonatal lethality. The gene discussed is WWTR1; the disease is cleft palate.