The retinoic acid (RA)-catabolizing enzyme Cyp26a1, enccoded by CYP26A1, plays an important role in protecting tailbud tissues from inappropriate exposure to RA.
Cyp26a1-null animals exhibit caudal agenesis and spina bifida, imperforate anus, agenesis of the caudal portions of the digestive and urogenital tracts, and malformed lumbosacral skeletal elements. This phenotype closely resembles the most severe form of caudal agenesis in humans.