RET and Hirschsprung disease: It’s clearly understandable how RET loss of function due to germline mutations, affecting those mechanism, can lead to a variety of congenital malformations such as Hirschsprung disease (HSCR) and congenital abnormalities of the kidney and urinary tract (CAKUT), and cause numerous symptoms in patients with phenotypic variants of these syndromes [14,15].