RET and Huntington disease: Of note, the congenital absence of the ganglion cells at the level of the myenteric and submucosal intestinal plexus (namely, HD) has been found amidst other syndromes such as trisomy 21, congenital central hypoventilation syndrome, and Mowat–Wilson syndrome, while (other than RET proto-oncogene) endothelin receptor type B (EDNRH) gene was the most frequent gene incriminated in HD [63].