Enteric nervous system (ENS) development is relevant to Hirschsprung's disease 
(HSCR; congenital aganglionosis of the terminal bowel), which is still 
imperfectly treated. Mutations in genes encoding the RET receptor tyrosine 
kinase and endothelin receptor type B (EDNRB) are involved in HSCR pathogenesis; 
however, also important in ENS development are molecules that mediate events 
that are more restricted than those of RET and EDNRB, act later in development 
and which might not be HSCR-associated. Examples are molecules that function in 
the guidance of enteric neural crest-derived cells (ENCDCs) and vagal axons, and 
in regulating the terminal differentiation of enteric neurons from ENCDCs. It is 
probable that highly prevalent disorders of gastrointestinal sensation and 
motility result from subtle defects in ENS development.