obsolete_Hirschsprung disease true 2.32 Congenital MEGACOLON resulting from the absence of ganglion cells (aganglionosis) in a distal segment of the LARGE INTESTINE. The aganglionic segment is permanently contracted thus causing dilatation proximal to it. In most cases, the aganglionic segment is within the RECTUM and SIGMOID COLON. Dani Welter use 'http://www.orpha.net/ORDO/Orphanet_388' instead. New Label : Hirschsprung disease congenital megacolon colonic aganglionosis Hirschsprung's disease http://www.orpha.net/ORDO/Orphanet_388 MESH:D006627 true