Hirschsprung Disease, Cardiac Defects, and Autonomic Dysfunction, also known as hcad, is related to hirschsprung disease 1 and heart disease. An important gene associated with Hirschsprung Disease, Cardiac Defects, and Autonomic Dysfunction is ECE1 (Endothelin Converting Enzyme 1). Affiliated tissues include smooth muscle and testis, and related phenotypes are hypertension and abnormal autonomic nervous system physiology