Endothelin receptor B mutant (Ednrb−/−) mice develop Hirschsprung’s disease, an abnormality of the enteric nervous system characterized by a lack of ganglion cells along a variable length of the distal intestine, resulting in the absence of peristalsis in the aganglionic segment and dilation of the colon proximally15. Here, EDNRB is linked to Hirschsprung disease.