Congenital diaphragmatic hernia (CDH) is a serious medical condition in which the developing diaphragm forms incompletely, leaving a hole through which the abdominal contents can enter the thoracic space and interfere with lung growth. A perturbation of the retinoid system has been linked to the etiology of CDH. This includes findings that nitrofen, which induces CDH in rodents, inhibits the key enzyme for retinoic acid (RA) production, retinaldehyde dehydrogenase-2 (RALDH2) in vitro.