While our Cre-line is known to affect foregut endoderm derivatives, we have evidence suggesting that it also affects developing kidneys, which originates from mesoderm (data not shown), and it is known that TAZ loss in development leads to significant cystic renal disease.32 Renal dysfunction could cause poor urine output, leading to insufficient amniotic fluid and subsequently poor lung development, a well-described constellation of findings known as Potter syndrome.33,34 Thus, impaired lung development may not be directly related to a genetic defect in this pup. This evidence concerns the gene WWTR1 and cystic kidney disease.