RET and Hirschsprung disease: RET is a receptor tyrosine kinase embedded in the cell membrane, encoded by the proto-oncogene RET.249 RET has been recognized as playing vital roles in various developmental processes, especially in the formation of the kidney and the enteric nervous system during embryonic development.250–252 Changes in RET have been linked to several diseases, including Hirschsprung’s disease and various types of cancer.253,254 Over the past thirty years, numerous alterations in RET have been identified that lead to continuous activation of its kinase activity, a key factor in many cancer subtypes.255–257