RET and Hirschsprung disease: Tumors with mutations involving C634 and M918T are also associated with more aggressive behavior in multiple endocrine neoplasia type 2 A (MEN2A) and MEN2B; mutations involving C634 and V804M are also associated with cutaneous lichen amyloidosis, while mutations involving codons 609, 611, 618 and 620 have been associated with Hirschsprung’s disease.